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<body class="book toc2 toc-left">
<div id="header">
<h1>Spring Cloud Sleuth</h1>
<div class="details">
<span id="author" class="author">Adrian Cole, Spencer Gibb, Marcin Grzejszczak, Dave Syer, Jay Bryant</span><br>
</div>
<div id="toc" class="toc2">
<div id="toctitle">Table of Contents</div>
<ul class="sectlevel1">
<li><a href="#_introduction">Introduction</a>
<ul class="sectlevel2">
<li><a href="#_terminology">Terminology</a></li>
<li><a href="#_purpose">Purpose</a>
<ul class="sectlevel3">
<li><a href="#_distributed_tracing_with_zipkin">Distributed Tracing with Zipkin</a></li>
<li><a href="#_visualizing_errors">Visualizing errors</a></li>
<li><a href="#_distributed_tracing_with_brave">Distributed Tracing with Brave</a></li>
<li><a href="#_live_examples">Live examples</a></li>
<li><a href="#_log_correlation">Log correlation</a>
<ul class="sectlevel4">
<li><a href="#_json_logback_with_logstash">JSON Logback with Logstash</a></li>
</ul>
</li>
<li><a href="#_propagating_span_context">Propagating Span Context</a>
<ul class="sectlevel4">
<li><a href="#_baggage_versus_span_tags">Baggage versus Span Tags</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#sleuth-adding-project">Adding Sleuth to the Project</a>
<ul class="sectlevel3">
<li><a href="#_only_sleuth_log_correlation">Only Sleuth (log correlation)</a></li>
<li><a href="#_sleuth_with_zipkin_via_http">Sleuth with Zipkin via HTTP</a></li>
<li><a href="#_sleuth_with_zipkin_over_rabbitmq_or_kafka">Sleuth with Zipkin over RabbitMQ or Kafka</a></li>
</ul>
</li>
<li><a href="#_overriding_the_auto_configuration_of_zipkin">Overriding the auto-configuration of Zipkin</a></li>
</ul>
</li>
<li><a href="#_additional_resources">Additional Resources</a></li>
<li><a href="#_features">Features</a>
<ul class="sectlevel2">
<li><a href="#_introduction_to_brave">Introduction to Brave</a>
<ul class="sectlevel3">
<li><a href="#_tracing">Tracing</a></li>
<li><a href="#_local_tracing">Local Tracing</a></li>
<li><a href="#_customizing_spans">Customizing Spans</a></li>
<li><a href="#_implicitly_looking_up_the_current_span">Implicitly Looking up the Current Span</a></li>
<li><a href="#_rpc_tracing">RPC tracing</a>
<ul class="sectlevel4">
<li><a href="#_one_way_tracing">One-Way tracing</a></li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
<li><a href="#_sampling">Sampling</a>
<ul class="sectlevel2">
<li><a href="#_declarative_sampling">Declarative sampling</a></li>
<li><a href="#_custom_sampling">Custom sampling</a></li>
<li><a href="#_sampling_in_spring_cloud_sleuth">Sampling in Spring Cloud Sleuth</a></li>
</ul>
</li>
<li><a href="#_propagation">Propagation</a>
<ul class="sectlevel2">
<li><a href="#_propagating_extra_fields">Propagating extra fields</a>
<ul class="sectlevel3">
<li><a href="#prefixed-fields">Prefixed fields</a></li>
<li><a href="#_extracting_a_propagated_context">Extracting a Propagated Context</a></li>
<li><a href="#_sharing_span_ids_between_client_and_server">Sharing span IDs between Client and Server</a></li>
<li><a href="#_implementing_propagation">Implementing Propagation</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#_current_tracing_component">Current Tracing Component</a></li>
<li><a href="#_current_span">Current Span</a>
<ul class="sectlevel2">
<li><a href="#_setting_a_span_in_scope_manually">Setting a span in scope manually</a></li>
</ul>
</li>
<li><a href="#_instrumentation">Instrumentation</a></li>
<li><a href="#_span_lifecycle">Span lifecycle</a>
<ul class="sectlevel2">
<li><a href="#creating-and-finishing-spans">Creating and finishing spans</a></li>
<li><a href="#continuing-spans">Continuing Spans</a></li>
<li><a href="#creating-spans-with-explicit-parent">Creating a Span with an explicit Parent</a></li>
</ul>
</li>
<li><a href="#_naming_spans">Naming spans</a>
<ul class="sectlevel2">
<li><a href="#_spanname_annotation"><code>@SpanName</code> Annotation</a></li>
<li><a href="#_tostring_method"><code>toString()</code> method</a></li>
</ul>
</li>
<li><a href="#_managing_spans_with_annotations">Managing Spans with Annotations</a>
<ul class="sectlevel2">
<li><a href="#_rationale">Rationale</a></li>
<li><a href="#_creating_new_spans">Creating New Spans</a></li>
<li><a href="#_continuing_spans">Continuing Spans</a></li>
<li><a href="#_advanced_tag_setting">Advanced Tag Setting</a>
<ul class="sectlevel3">
<li><a href="#_custom_extractor">Custom extractor</a></li>
<li><a href="#_resolving_expressions_for_a_value">Resolving Expressions for a Value</a></li>
<li><a href="#_using_the_tostring_method">Using the <code>toString()</code> method</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#_customizations">Customizations</a>
<ul class="sectlevel2">
<li><a href="#_http">HTTP</a></li>
<li><a href="#_tracingfilter"><code>TracingFilter</code></a></li>
<li><a href="#_custom_service_name">Custom service name</a></li>
<li><a href="#_customization_of_reported_spans">Customization of Reported Spans</a></li>
<li><a href="#_host_locator">Host Locator</a></li>
</ul>
</li>
<li><a href="#_sending_spans_to_zipkin">Sending Spans to Zipkin</a></li>
<li><a href="#_zipkin_stream_span_consumer">Zipkin Stream Span Consumer</a></li>
<li><a href="#_integrations">Integrations</a>
<ul class="sectlevel2">
<li><a href="#_opentracing">OpenTracing</a></li>
<li><a href="#_runnable_and_callable">Runnable and Callable</a></li>
<li><a href="#_hystrix">Hystrix</a>
<ul class="sectlevel3">
<li><a href="#_custom_concurrency_strategy">Custom Concurrency Strategy</a></li>
<li><a href="#_manual_command_setting">Manual Command setting</a></li>
</ul>
</li>
<li><a href="#_rxjava">RxJava</a></li>
<li><a href="#_http_integration">HTTP integration</a>
<ul class="sectlevel3">
<li><a href="#_http_filter">HTTP Filter</a></li>
<li><a href="#_handlerinterceptor">HandlerInterceptor</a></li>
<li><a href="#_async_servlet_support">Async Servlet support</a></li>
<li><a href="#_webflux_support">WebFlux support</a></li>
<li><a href="#_dubbo_rpc_support">Dubbo RPC support</a></li>
</ul>
</li>
<li><a href="#_http_client_integration">HTTP Client Integration</a>
<ul class="sectlevel3">
<li><a href="#_synchronous_rest_template">Synchronous Rest Template</a></li>
<li><a href="#_asynchronous_rest_template">Asynchronous Rest Template</a>
<ul class="sectlevel4">
<li><a href="#_multiple_asynchronous_rest_templates">Multiple Asynchronous Rest Templates</a></li>
</ul>
</li>
<li><a href="#_webclient"><code>WebClient</code></a></li>
<li><a href="#_traverson">Traverson</a></li>
<li><a href="#_apache_httpclientbuilder_and_httpasyncclientbuilder">Apache <code>HttpClientBuilder</code> and <code>HttpAsyncClientBuilder</code></a></li>
<li><a href="#_netty_httpclient">Netty <code>HttpClient</code></a></li>
<li><a href="#_userinforesttemplatecustomizer"><code>UserInfoRestTemplateCustomizer</code></a></li>
</ul>
</li>
<li><a href="#_feign">Feign</a></li>
<li><a href="#_grpc">gRPC</a>
<ul class="sectlevel3">
<li><a href="#_variant_1">Variant 1</a>
<ul class="sectlevel4">
<li><a href="#_dependencies">Dependencies</a></li>
<li><a href="#_server_instrumentation">Server Instrumentation</a></li>
<li><a href="#_client_instrumentation">Client Instrumentation</a></li>
</ul>
</li>
<li><a href="#_variant_2">Variant 2</a></li>
</ul>
</li>
<li><a href="#_asynchronous_communication">Asynchronous Communication</a>
<ul class="sectlevel3">
<li><a href="#_async_annotated_methods"><code>@Async</code> Annotated methods</a></li>
<li><a href="#_scheduled_annotated_methods"><code>@Scheduled</code> Annotated Methods</a></li>
<li><a href="#_executor_executorservice_and_scheduledexecutorservice">Executor, ExecutorService, and ScheduledExecutorService</a>
<ul class="sectlevel4">
<li><a href="#_customization_of_executors">Customization of Executors</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#_messaging">Messaging</a>
<ul class="sectlevel3">
<li><a href="#_spring_integration_and_spring_cloud_stream">Spring Integration and Spring Cloud Stream</a></li>
<li><a href="#_spring_rabbitmq">Spring RabbitMq</a></li>
<li><a href="#_spring_kafka">Spring Kafka</a></li>
<li><a href="#_spring_kafka_streams">Spring Kafka Streams</a></li>
<li><a href="#_spring_jms">Spring JMS</a></li>
</ul>
</li>
<li><a href="#_zuul">Zuul</a></li>
<li><a href="#_redis">Redis</a></li>
</ul>
</li>
<li><a href="#_running_examples">Running examples</a></li>
</ul>
</div>
</div>
<div id="content">
<div id="preamble">
<div class="sectionbody">
<div class="paragraph">
<p><strong>2.2.0.M2</strong></p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_introduction"><a class="link" href="#_introduction">Introduction</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>Spring Cloud Sleuth implements a distributed tracing solution for <a href="https://cloud.spring.io">Spring Cloud</a>.</p>
</div>
<div class="sect2">
<h3 id="_terminology"><a class="link" href="#_terminology">Terminology</a></h3>
<div class="paragraph">
<p>Spring Cloud Sleuth borrows <a href="https://research.google.com/pubs/pub36356.html">Dapper&#8217;s</a> terminology.</p>
</div>
<div class="paragraph">
<p><strong>Span</strong>: The basic unit of work. For example, sending an RPC is a new span, as is sending a response to an RPC.
Spans are identified by a unique 64-bit ID for the span and another 64-bit ID for the trace the span is a part of.
Spans also have other data, such as descriptions, timestamped events, key-value annotations (tags), the ID of the span that caused them, and process IDs (normally IP addresses).</p>
</div>
<div class="paragraph">
<p>Spans can be started and stopped, and they keep track of their timing information.
Once you create a span, you must stop it at some point in the future.</p>
</div>
<div class="admonitionblock tip">
<table>
<tr>
<td class="icon">
<i class="fa icon-tip" title="Tip"></i>
</td>
<td class="content">
The initial span that starts a trace is called a <code>root span</code>. The value of the ID
of that span is equal to the trace ID.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p><strong>Trace:</strong> A set of spans forming a tree-like structure.
For example, if you run a distributed big-data store, a trace might be formed by a <code>PUT</code> request.</p>
</div>
<div class="paragraph">
<p><strong>Annotation:</strong> Used to record the existence of an event in time. With
<a href="https://github.com/openzipkin/brave">Brave</a> instrumentation, we no longer need to set special events
for <a href="https://zipkin.io/">Zipkin</a> to understand who the client and server are, where
the request started, and where it ended. For learning purposes,
however, we mark these events to highlight what kind
of an action took place.</p>
</div>
<div class="ulist">
<ul>
<li>
<p><strong>cs</strong>: Client Sent. The client has made a request. This annotation indicates the start of the span.</p>
</li>
<li>
<p><strong>sr</strong>: Server Received: The server side got the request and started processing it.
Subtracting the <code>cs</code> timestamp from this timestamp reveals the network latency.</p>
</li>
<li>
<p><strong>ss</strong>: Server Sent. Annotated upon completion of request processing (when the response got sent back to the client).
Subtracting the <code>sr</code> timestamp from this timestamp reveals the time needed by the server side to process the request.</p>
</li>
<li>
<p><strong>cr</strong>: Client Received. Signifies the end of the span.
The client has successfully received the response from the server side.
Subtracting the <code>cs</code> timestamp from this timestamp reveals the whole time needed by the client to receive the response from the server.</p>
</li>
</ul>
</div>
<div class="paragraph">
<p>The following image shows how <strong>Span</strong> and <strong>Trace</strong> look in a system, together with the Zipkin annotations:</p>
</div>
<div class="imageblock">
<div class="content">
<img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-sleuth/master/docs/src/main/asciidoc/images/trace-id.png" alt="Trace Info propagation">
</div>
</div>
<div class="paragraph">
<p>Each color of a note signifies a span (there are seven spans - from <strong>A</strong> to <strong>G</strong>).
Consider the following note:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code>Trace Id = X
Span Id = D
Client Sent</code></pre>
</div>
</div>
<div class="paragraph">
<p>This note indicates that the current span has <strong>Trace Id</strong> set to <strong>X</strong> and <strong>Span Id</strong> set to <strong>D</strong>.
Also, the <code>Client Sent</code> event took place.</p>
</div>
<div class="paragraph">
<p>The following image shows how parent-child relationships of spans look:</p>
</div>
<div class="imageblock">
<div class="content">
<img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-sleuth/master/docs/src/main/asciidoc/images/parents.png" alt="Parent child relationship">
</div>
</div>
</div>
<div class="sect2">
<h3 id="_purpose"><a class="link" href="#_purpose">Purpose</a></h3>
<div class="paragraph">
<p>The following sections refer to the example shown in the preceding image.</p>
</div>
<div class="sect3">
<h4 id="_distributed_tracing_with_zipkin"><a class="link" href="#_distributed_tracing_with_zipkin">Distributed Tracing with Zipkin</a></h4>
<div class="paragraph">
<p>This example has seven spans.
If you go to traces in Zipkin, you can see this number in the second trace, as shown in the following image:</p>
</div>
<div class="imageblock">
<div class="content">
<img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-sleuth/master/docs/src/main/asciidoc/images/zipkin-traces.png" alt="Traces">
</div>
</div>
<div class="paragraph">
<p>However, if you pick a particular trace, you can see four spans, as shown in the following image:</p>
</div>
<div class="imageblock">
<div class="content">
<img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-sleuth/master/docs/src/main/asciidoc/images/zipkin-ui.png" alt="Traces Info propagation">
</div>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<i class="fa icon-note" title="Note"></i>
</td>
<td class="content">
When you pick a particular trace, you see merged spans.
That means that, if there were two spans sent to Zipkin with Server Received and Server Sent or Client Received and Client Sent annotations, they are presented as a single span.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>Why is there a difference between the seven and four spans in this case?</p>
</div>
<div class="ulist">
<ul>
<li>
<p>One span comes from the <code>http:/start</code> span. It has the Server Received (<code>sr</code>) and Server Sent (<code>ss</code>) annotations.</p>
</li>
<li>
<p>Two spans come from the RPC call from <code>service1</code> to <code>service2</code> to the <code>http:/foo</code> endpoint.
The Client Sent (<code>cs</code>) and Client Received (<code>cr</code>) events took place on the <code>service1</code> side.
Server Received (<code>sr</code>) and Server Sent (<code>ss</code>) events took place on the <code>service2</code> side.
These two spans form one logical span related to an RPC call.</p>
</li>
<li>
<p>Two spans come from the RPC call from <code>service2</code> to <code>service3</code> to the <code>http:/bar</code> endpoint.
The Client Sent (<code>cs</code>) and Client Received (<code>cr</code>) events took place on the <code>service2</code> side.
The Server Received (<code>sr</code>) and Server Sent (<code>ss</code>) events took place on the <code>service3</code> side.
These two spans form one logical span related to an RPC call.</p>
</li>
<li>
<p>Two spans come from the RPC call from <code>service2</code> to <code>service4</code> to the <code>http:/baz</code> endpoint.
The Client Sent (<code>cs</code>) and Client Received (<code>cr</code>) events took place on the <code>service2</code> side.
Server Received (<code>sr</code>) and Server Sent (<code>ss</code>) events took place on the <code>service4</code> side.
These two spans form one logical span related to an RPC call.</p>
</li>
</ul>
</div>
<div class="paragraph">
<p>So, if we count the physical spans, we have one from <code>http:/start</code>, two from <code>service1</code> calling <code>service2</code>, two from <code>service2</code>
calling <code>service3</code>, and two from <code>service2</code> calling <code>service4</code>. In sum, we have a total of seven spans.</p>
</div>
<div class="paragraph">
<p>Logically, we see the information of four total Spans because we have one span related to the incoming request
to <code>service1</code> and three spans related to RPC calls.</p>
</div>
</div>
<div class="sect3">
<h4 id="_visualizing_errors"><a class="link" href="#_visualizing_errors">Visualizing errors</a></h4>
<div class="paragraph">
<p>Zipkin lets you visualize errors in your trace.
When an exception was thrown and was not caught, we set proper tags on the span, which Zipkin can then properly colorize.
You could see in the list of traces one trace that is red. That appears because an exception was thrown.</p>
</div>
<div class="paragraph">
<p>If you click that trace, you see a similar picture, as follows:</p>
</div>
<div class="imageblock">
<div class="content">
<img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-sleuth/master/docs/src/main/asciidoc/images/zipkin-error-traces.png" alt="Error Traces">
</div>
</div>
<div class="paragraph">
<p>If you then click on one of the spans, you see the following</p>
</div>
<div class="imageblock">
<div class="content">
<img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-sleuth/master/docs/src/main/asciidoc/images/zipkin-error-trace-screenshot.png" alt="Error Traces Info propagation">
</div>
</div>
<div class="paragraph">
<p>The span shows the reason for the error and the whole stack trace related to it.</p>
</div>
</div>
<div class="sect3">
<h4 id="_distributed_tracing_with_brave"><a class="link" href="#_distributed_tracing_with_brave">Distributed Tracing with Brave</a></h4>
<div class="paragraph">
<p>Starting with version <code>2.0.0</code>, Spring Cloud Sleuth uses <a href="https://github.com/openzipkin/brave">Brave</a> as the tracing library.
Consequently, Sleuth no longer takes care of storing the context but delegates that work to Brave.</p>
</div>
<div class="paragraph">
<p>Due to the fact that Sleuth had different naming and tagging conventions than Brave, we decided to follow Brave&#8217;s conventions from now on.
However, if you want to use the legacy Sleuth approaches, you can set the <code>spring.sleuth.http.legacy.enabled</code> property to <code>true</code>.</p>
</div>
</div>
<div class="sect3">
<h4 id="_live_examples"><a class="link" href="#_live_examples">Live examples</a></h4>
<div class="imageblock">
<div class="content">
<a class="image" href="https://docssleuth-zipkin-server.cfapps.io/"><img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-sleuth/master/docs/src/main/asciidoc/images/pws.png" alt="Zipkin deployed on Pivotal Web Services" width="150" height="74"></a>
</div>
<div class="title">Click the Pivotal Web Services icon to see it live!Click the Pivotal Web Services icon to see it live!</div>
</div>
<div class="paragraph">
<p><a href="https://docssleuth-zipkin-server.cfapps.io/">Click here to see it live!</a></p>
</div>
<div class="paragraph">
<p>The dependency graph in Zipkin should resemble the following image:</p>
</div>
<div class="imageblock">
<div class="content">
<img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-sleuth/master/docs/src/main/asciidoc/images/dependencies.png" alt="Dependencies">
</div>
</div>
<div class="imageblock">
<div class="content">
<a class="image" href="https://docssleuth-zipkin-server.cfapps.io/dependency"><img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-sleuth/master/docs/src/main/asciidoc/images/pws.png" alt="Zipkin deployed on Pivotal Web Services" width="150" height="74"></a>
</div>
<div class="title">Click the Pivotal Web Services icon to see it live!Click the Pivotal Web Services icon to see it live!</div>
</div>
<div class="paragraph">
<p><a href="https://docssleuth-zipkin-server.cfapps.io/dependency">Click here to see it live!</a></p>
</div>
</div>
<div class="sect3">
<h4 id="_log_correlation"><a class="link" href="#_log_correlation">Log correlation</a></h4>
<div class="paragraph">
<p>When using grep to read the logs of those four applications by scanning for a trace ID equal to (for example) <code>2485ec27856c56f4</code>, you get output resembling the following:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code>service1.log:2016-02-26 11:15:47.561 INFO [service1,2485ec27856c56f4,2485ec27856c56f4,true] 68058 --- [nio-8081-exec-1] i.s.c.sleuth.docs.service1.Application : Hello from service1. Calling service2
service2.log:2016-02-26 11:15:47.710 INFO [service2,2485ec27856c56f4,9aa10ee6fbde75fa,true] 68059 --- [nio-8082-exec-1] i.s.c.sleuth.docs.service2.Application : Hello from service2. Calling service3 and then service4
service3.log:2016-02-26 11:15:47.895 INFO [service3,2485ec27856c56f4,1210be13194bfe5,true] 68060 --- [nio-8083-exec-1] i.s.c.sleuth.docs.service3.Application : Hello from service3
service2.log:2016-02-26 11:15:47.924 INFO [service2,2485ec27856c56f4,9aa10ee6fbde75fa,true] 68059 --- [nio-8082-exec-1] i.s.c.sleuth.docs.service2.Application : Got response from service3 [Hello from service3]
service4.log:2016-02-26 11:15:48.134 INFO [service4,2485ec27856c56f4,1b1845262ffba49d,true] 68061 --- [nio-8084-exec-1] i.s.c.sleuth.docs.service4.Application : Hello from service4
service2.log:2016-02-26 11:15:48.156 INFO [service2,2485ec27856c56f4,9aa10ee6fbde75fa,true] 68059 --- [nio-8082-exec-1] i.s.c.sleuth.docs.service2.Application : Got response from service4 [Hello from service4]
service1.log:2016-02-26 11:15:48.182 INFO [service1,2485ec27856c56f4,2485ec27856c56f4,true] 68058 --- [nio-8081-exec-1] i.s.c.sleuth.docs.service1.Application : Got response from service2 [Hello from service2, response from service3 [Hello from service3] and from service4 [Hello from service4]]</code></pre>
</div>
</div>
<div class="paragraph">
<p>If you use a log aggregating tool (such as <a href="https://www.elastic.co/products/kibana">Kibana</a>, <a href="https://www.splunk.com/">Splunk</a>, and others), you can order the events that took place.
An example from Kibana would resemble the following image:</p>
</div>
<div class="imageblock">
<div class="content">
<img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-sleuth/master/docs/src/main/asciidoc/images/kibana.png" alt="Log correlation with Kibana">
</div>
</div>
<div class="paragraph">
<p>If you want to use <a href="https://www.elastic.co/guide/en/logstash/current/index.html">Logstash</a>, the following listing shows the Grok pattern for Logstash:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code>filter {
# pattern matching logback pattern
grok {
match =&gt; { "message" =&gt; "%{TIMESTAMP_ISO8601:timestamp}\s+%{LOGLEVEL:severity}\s+\[%{DATA:service},%{DATA:trace},%{DATA:span},%{DATA:exportable}\]\s+%{DATA:pid}\s+---\s+\[%{DATA:thread}\]\s+%{DATA:class}\s+:\s+%{GREEDYDATA:rest}" }
}
}</code></pre>
</div>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<i class="fa icon-note" title="Note"></i>
</td>
<td class="content">
If you want to use Grok together with the logs from Cloud Foundry, you have to use the following pattern:
</td>
</tr>
</table>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code>filter {
# pattern matching logback pattern
grok {
match =&gt; { "message" =&gt; "(?m)OUT\s+%{TIMESTAMP_ISO8601:timestamp}\s+%{LOGLEVEL:severity}\s+\[%{DATA:service},%{DATA:trace},%{DATA:span},%{DATA:exportable}\]\s+%{DATA:pid}\s+---\s+\[%{DATA:thread}\]\s+%{DATA:class}\s+:\s+%{GREEDYDATA:rest}" }
}
}</code></pre>
</div>
</div>
<div class="sect4">
<h5 id="_json_logback_with_logstash"><a class="link" href="#_json_logback_with_logstash">JSON Logback with Logstash</a></h5>
<div class="paragraph">
<p>Often, you do not want to store your logs in a text file but in a JSON file that Logstash can immediately pick.
To do so, you have to do the following (for readability, we pass the dependencies in the <code>groupId:artifactId:version</code> notation).</p>
</div>
<div class="paragraph">
<p><strong>Dependencies Setup</strong></p>
</div>
<div class="olist arabic">
<ol class="arabic">
<li>
<p>Ensure that Logback is on the classpath (<code>ch.qos.logback:logback-core</code>).</p>
</li>
<li>
<p>Add Logstash Logback encode. For example, to use version <code>4.6</code>, add <code>net.logstash.logback:logstash-logback-encoder:4.6</code>.</p>
</li>
</ol>
</div>
<div class="paragraph">
<p><strong>Logback Setup</strong></p>
</div>
<div class="paragraph">
<p>Consider the following example of a Logback configuration file (named <a href="https://github.com/spring-cloud-samples/sleuth-documentation-apps/blob/master/service1/src/main/resources/logback-spring.xml">logback-spring.xml</a>).</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-xml hljs" data-lang="xml">&lt;?xml version="1.0" encoding="UTF-8"?&gt;
&lt;configuration&gt;
&lt;include resource="org/springframework/boot/logging/logback/defaults.xml"/&gt;
​
&lt;springProperty scope="context" name="springAppName" source="spring.application.name"/&gt;
&lt;!-- Example for logging into the build folder of your project --&gt;
&lt;property name="LOG_FILE" value="${BUILD_FOLDER:-build}/${springAppName}"/&gt;​
&lt;!-- You can override this to have a custom pattern --&gt;
&lt;property name="CONSOLE_LOG_PATTERN"
value="%clr(%d{yyyy-MM-dd HH:mm:ss.SSS}){faint} %clr(${LOG_LEVEL_PATTERN:-%5p}) %clr(${PID:- }){magenta} %clr(---){faint} %clr([%15.15t]){faint} %clr(%-40.40logger{39}){cyan} %clr(:){faint} %m%n${LOG_EXCEPTION_CONVERSION_WORD:-%wEx}"/&gt;
&lt;!-- Appender to log to console --&gt;
&lt;appender name="console" class="ch.qos.logback.core.ConsoleAppender"&gt;
&lt;filter class="ch.qos.logback.classic.filter.ThresholdFilter"&gt;
&lt;!-- Minimum logging level to be presented in the console logs--&gt;
&lt;level&gt;DEBUG&lt;/level&gt;
&lt;/filter&gt;
&lt;encoder&gt;
&lt;pattern&gt;${CONSOLE_LOG_PATTERN}&lt;/pattern&gt;
&lt;charset&gt;utf8&lt;/charset&gt;
&lt;/encoder&gt;
&lt;/appender&gt;
&lt;!-- Appender to log to file --&gt;​
&lt;appender name="flatfile" class="ch.qos.logback.core.rolling.RollingFileAppender"&gt;
&lt;file&gt;${LOG_FILE}&lt;/file&gt;
&lt;rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy"&gt;
&lt;fileNamePattern&gt;${LOG_FILE}.%d{yyyy-MM-dd}.gz&lt;/fileNamePattern&gt;
&lt;maxHistory&gt;7&lt;/maxHistory&gt;
&lt;/rollingPolicy&gt;
&lt;encoder&gt;
&lt;pattern&gt;${CONSOLE_LOG_PATTERN}&lt;/pattern&gt;
&lt;charset&gt;utf8&lt;/charset&gt;
&lt;/encoder&gt;
&lt;/appender&gt;
​
&lt;!-- Appender to log to file in a JSON format --&gt;
&lt;appender name="logstash" class="ch.qos.logback.core.rolling.RollingFileAppender"&gt;
&lt;file&gt;${LOG_FILE}.json&lt;/file&gt;
&lt;rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy"&gt;
&lt;fileNamePattern&gt;${LOG_FILE}.json.%d{yyyy-MM-dd}.gz&lt;/fileNamePattern&gt;
&lt;maxHistory&gt;7&lt;/maxHistory&gt;
&lt;/rollingPolicy&gt;
&lt;encoder class="net.logstash.logback.encoder.LoggingEventCompositeJsonEncoder"&gt;
&lt;providers&gt;
&lt;timestamp&gt;
&lt;timeZone&gt;UTC&lt;/timeZone&gt;
&lt;/timestamp&gt;
&lt;pattern&gt;
&lt;pattern&gt;
{
"severity": "%level",
"service": "${springAppName:-}",
"trace": "%X{X-B3-TraceId:-}",
"span": "%X{X-B3-SpanId:-}",
"parent": "%X{X-B3-ParentSpanId:-}",
"exportable": "%X{X-Span-Export:-}",
"pid": "${PID:-}",
"thread": "%thread",
"class": "%logger{40}",
"rest": "%message"
}
&lt;/pattern&gt;
&lt;/pattern&gt;
&lt;/providers&gt;
&lt;/encoder&gt;
&lt;/appender&gt;
​
&lt;root level="INFO"&gt;
&lt;appender-ref ref="console"/&gt;
&lt;!-- uncomment this to have also JSON logs --&gt;
&lt;!--&lt;appender-ref ref="logstash"/&gt;--&gt;
&lt;!--&lt;appender-ref ref="flatfile"/&gt;--&gt;
&lt;/root&gt;
&lt;/configuration&gt;</code></pre>
</div>
</div>
<div class="paragraph">
<p>That Logback configuration file:</p>
</div>
<div class="ulist">
<ul>
<li>
<p>Logs information from the application in a JSON format to a <code>build/${spring.application.name}.json</code> file.</p>
</li>
<li>
<p>Has commented out two additional appenders: console and standard log file.</p>
</li>
<li>
<p>Has the same logging pattern as the one presented in the previous section.</p>
</li>
</ul>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<i class="fa icon-note" title="Note"></i>
</td>
<td class="content">
If you use a custom <code>logback-spring.xml</code>, you must pass the <code>spring.application.name</code> in the <code>bootstrap</code> rather than the <code>application</code> property file.
Otherwise, your custom logback file does not properly read the property.
</td>
</tr>
</table>
</div>
</div>
</div>
<div class="sect3">
<h4 id="_propagating_span_context"><a class="link" href="#_propagating_span_context">Propagating Span Context</a></h4>
<div class="paragraph">
<p>The span context is the state that must get propagated to any child spans across process boundaries.
Part of the Span Context is the Baggage. The trace and span IDs are a required part of the span context.
Baggage is an optional part.</p>
</div>
<div class="paragraph">
<p>Baggage is a set of key:value pairs stored in the span context.
Baggage travels together with the trace and is attached to every span.
Spring Cloud Sleuth understands that a header is baggage-related if the HTTP header is prefixed with <code>baggage-</code> and, for messaging, it starts with <code>baggage_</code>.</p>
</div>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
There is currently no limitation of the count or size of baggage items.
However, keep in mind that too many can decrease system throughput or increase RPC latency.
In extreme cases, too much baggage can crash the application, due to exceeding transport-level message or header capacity.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>The following example shows setting baggage on a span:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">Span initialSpan = this.tracer.nextSpan().name("span").start();
ExtraFieldPropagation.set(initialSpan.context(), "foo", "bar");
ExtraFieldPropagation.set(initialSpan.context(), "UPPER_CASE", "someValue");</code></pre>
</div>
</div>
<div class="sect4">
<h5 id="_baggage_versus_span_tags"><a class="link" href="#_baggage_versus_span_tags">Baggage versus Span Tags</a></h5>
<div class="paragraph">
<p>Baggage travels with the trace (every child span contains the baggage of its parent).
Zipkin has no knowledge of baggage and does not receive that information.</p>
</div>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
Starting from Sleuth 2.0.0 you have to pass the baggage key names explicitly
in your project configuration. Read more about that setup <a href="#prefixed-fields">here</a>
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>Tags are attached to a specific span. In other words, they are presented only for that particular span.
However, you can search by tag to find the trace, assuming a span having the searched tag value exists.</p>
</div>
<div class="paragraph">
<p>If you want to be able to lookup a span based on baggage, you should add a corresponding entry as a tag in the root span.</p>
</div>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
The span must be in scope.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>The following listing shows integration tests that use baggage:</p>
</div>
<div class="listingblock">
<div class="title">The setup</div>
<div class="content">
<pre class="highlightjs highlight"><code class="language-yml hljs" data-lang="yml">spring.sleuth:
baggage-keys:
- baz
- bizarrecase
propagation-keys:
- foo
- upper_case</code></pre>
</div>
</div>
<div class="listingblock">
<div class="title">The code</div>
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">initialSpan.tag("foo",
ExtraFieldPropagation.get(initialSpan.context(), "foo"));
initialSpan.tag("UPPER_CASE",
ExtraFieldPropagation.get(initialSpan.context(), "UPPER_CASE"));</code></pre>
</div>
</div>
</div>
</div>
</div>
<div class="sect2">
<h3 id="sleuth-adding-project"><a class="link" href="#sleuth-adding-project">Adding Sleuth to the Project</a></h3>
<div class="paragraph">
<p>This section addresses how to add Sleuth to your project with either Maven or Gradle.</p>
</div>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
To ensure that your application name is properly displayed in Zipkin, set the <code>spring.application.name</code> property in <code>bootstrap.yml</code>.
</td>
</tr>
</table>
</div>
<div class="sect3">
<h4 id="_only_sleuth_log_correlation"><a class="link" href="#_only_sleuth_log_correlation">Only Sleuth (log correlation)</a></h4>
<div class="paragraph">
<p>If you want to use only Spring Cloud Sleuth without the Zipkin integration, add the <code>spring-cloud-starter-sleuth</code> module to your project.</p>
</div>
<div class="paragraph">
<p>The following example shows how to add Sleuth with Maven:</p>
</div>
<div class="listingblock primary">
<div class="title">Maven</div>
<div class="content">
<pre class="highlightjs highlight"><code class="language-xml hljs" data-lang="xml">&lt;dependencyManagement&gt; <i class="conum" data-value="1"></i><b>(1)</b>
&lt;dependencies&gt;
&lt;dependency&gt;
&lt;groupId&gt;org.springframework.cloud&lt;/groupId&gt;
&lt;artifactId&gt;spring-cloud-dependencies&lt;/artifactId&gt;
&lt;version&gt;${release.train.version}&lt;/version&gt;
&lt;type&gt;pom&lt;/type&gt;
&lt;scope&gt;import&lt;/scope&gt;
&lt;/dependency&gt;
&lt;/dependencies&gt;
&lt;/dependencyManagement&gt;
&lt;dependency&gt; <i class="conum" data-value="2"></i><b>(2)</b>
&lt;groupId&gt;org.springframework.cloud&lt;/groupId&gt;
&lt;artifactId&gt;spring-cloud-starter-sleuth&lt;/artifactId&gt;
&lt;/dependency&gt;</code></pre>
</div>
</div>
<div class="colist arabic">
<table>
<tr>
<td><i class="conum" data-value="1"></i><b>1</b></td>
<td>We recommend that you add the dependency management through the Spring BOM so that you need not manage versions yourself.</td>
</tr>
<tr>
<td><i class="conum" data-value="2"></i><b>2</b></td>
<td>Add the dependency to <code>spring-cloud-starter-sleuth</code>.</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>The following example shows how to add Sleuth with Gradle:</p>
</div>
<div class="listingblock secondary">
<div class="title">Gradle</div>
<div class="content">
<pre class="highlightjs highlight"><code class="language-groovy hljs" data-lang="groovy">dependencyManagement { <i class="conum" data-value="1"></i><b>(1)</b>
imports {
mavenBom "org.springframework.cloud:spring-cloud-dependencies:${releaseTrainVersion}"
}
}
dependencies { <i class="conum" data-value="2"></i><b>(2)</b>
compile "org.springframework.cloud:spring-cloud-starter-sleuth"
}</code></pre>
</div>
</div>
<div class="colist arabic">
<table>
<tr>
<td><i class="conum" data-value="1"></i><b>1</b></td>
<td>We recommend that you add the dependency management through the Spring BOM so that you need not manage versions yourself.</td>
</tr>
<tr>
<td><i class="conum" data-value="2"></i><b>2</b></td>
<td>Add the dependency to <code>spring-cloud-starter-sleuth</code>.</td>
</tr>
</table>
</div>
</div>
<div class="sect3">
<h4 id="_sleuth_with_zipkin_via_http"><a class="link" href="#_sleuth_with_zipkin_via_http">Sleuth with Zipkin via HTTP</a></h4>
<div class="paragraph">
<p>If you want both Sleuth and Zipkin, add the <code>spring-cloud-starter-zipkin</code> dependency.</p>
</div>
<div class="paragraph">
<p>The following example shows how to do so for Maven:</p>
</div>
<div class="listingblock primary">
<div class="title">Maven</div>
<div class="content">
<pre class="highlightjs highlight"><code class="language-xml hljs" data-lang="xml">&lt;dependencyManagement&gt; <i class="conum" data-value="1"></i><b>(1)</b>
&lt;dependencies&gt;
&lt;dependency&gt;
&lt;groupId&gt;org.springframework.cloud&lt;/groupId&gt;
&lt;artifactId&gt;spring-cloud-dependencies&lt;/artifactId&gt;
&lt;version&gt;${release.train.version}&lt;/version&gt;
&lt;type&gt;pom&lt;/type&gt;
&lt;scope&gt;import&lt;/scope&gt;
&lt;/dependency&gt;
&lt;/dependencies&gt;
&lt;/dependencyManagement&gt;
&lt;dependency&gt; <i class="conum" data-value="2"></i><b>(2)</b>
&lt;groupId&gt;org.springframework.cloud&lt;/groupId&gt;
&lt;artifactId&gt;spring-cloud-starter-zipkin&lt;/artifactId&gt;
&lt;/dependency&gt;</code></pre>
</div>
</div>
<div class="colist arabic">
<table>
<tr>
<td><i class="conum" data-value="1"></i><b>1</b></td>
<td>We recommend that you add the dependency management through the Spring BOM so that you need not manage versions yourself.</td>
</tr>
<tr>
<td><i class="conum" data-value="2"></i><b>2</b></td>
<td>Add the dependency to <code>spring-cloud-starter-zipkin</code>.</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>The following example shows how to do so for Gradle:</p>
</div>
<div class="listingblock secondary">
<div class="title">Gradle</div>
<div class="content">
<pre class="highlightjs highlight"><code class="language-groovy hljs" data-lang="groovy">dependencyManagement { <i class="conum" data-value="1"></i><b>(1)</b>
imports {
mavenBom "org.springframework.cloud:spring-cloud-dependencies:${releaseTrainVersion}"
}
}
dependencies { <i class="conum" data-value="2"></i><b>(2)</b>
compile "org.springframework.cloud:spring-cloud-starter-zipkin"
}</code></pre>
</div>
</div>
<div class="colist arabic">
<table>
<tr>
<td><i class="conum" data-value="1"></i><b>1</b></td>
<td>We recommend that you add the dependency management through the Spring BOM so that you need not manage versions yourself.</td>
</tr>
<tr>
<td><i class="conum" data-value="2"></i><b>2</b></td>
<td>Add the dependency to <code>spring-cloud-starter-zipkin</code>.</td>
</tr>
</table>
</div>
</div>
<div class="sect3">
<h4 id="_sleuth_with_zipkin_over_rabbitmq_or_kafka"><a class="link" href="#_sleuth_with_zipkin_over_rabbitmq_or_kafka">Sleuth with Zipkin over RabbitMQ or Kafka</a></h4>
<div class="paragraph">
<p>If you want to use RabbitMQ or Kafka instead of HTTP, add the <code>spring-rabbit</code> or <code>spring-kafka</code> dependency.
The default destination name is <code>zipkin</code>.</p>
</div>
<div class="paragraph">
<p>If using Kafka, you must set the property <code>spring.zipkin.sender.type</code> property accordingly:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-yaml hljs" data-lang="yaml">spring.zipkin.sender.type: kafka</code></pre>
</div>
</div>
<div class="admonitionblock caution">
<table>
<tr>
<td class="icon">
<i class="fa icon-caution" title="Caution"></i>
</td>
<td class="content">
<code>spring-cloud-sleuth-stream</code> is deprecated and incompatible with these destinations.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>If you want Sleuth over RabbitMQ, add the <code>spring-cloud-starter-zipkin</code> and <code>spring-rabbit</code>
dependencies.</p>
</div>
<div class="paragraph">
<p>The following example shows how to do so for Gradle:</p>
</div>
<div class="listingblock primary">
<div class="title">Maven</div>
<div class="content">
<pre class="highlightjs highlight"><code class="language-xml hljs" data-lang="xml">&lt;dependencyManagement&gt; <i class="conum" data-value="1"></i><b>(1)</b>
&lt;dependencies&gt;
&lt;dependency&gt;
&lt;groupId&gt;org.springframework.cloud&lt;/groupId&gt;
&lt;artifactId&gt;spring-cloud-dependencies&lt;/artifactId&gt;
&lt;version&gt;${release.train.version}&lt;/version&gt;
&lt;type&gt;pom&lt;/type&gt;
&lt;scope&gt;import&lt;/scope&gt;
&lt;/dependency&gt;
&lt;/dependencies&gt;
&lt;/dependencyManagement&gt;
&lt;dependency&gt; <i class="conum" data-value="2"></i><b>(2)</b>
&lt;groupId&gt;org.springframework.cloud&lt;/groupId&gt;
&lt;artifactId&gt;spring-cloud-starter-zipkin&lt;/artifactId&gt;
&lt;/dependency&gt;
&lt;dependency&gt; <i class="conum" data-value="3"></i><b>(3)</b>
&lt;groupId&gt;org.springframework.amqp&lt;/groupId&gt;
&lt;artifactId&gt;spring-rabbit&lt;/artifactId&gt;
&lt;/dependency&gt;</code></pre>
</div>
</div>
<div class="colist arabic">
<table>
<tr>
<td><i class="conum" data-value="1"></i><b>1</b></td>
<td>We recommend that you add the dependency management through the Spring BOM so that you need not manage versions yourself.</td>
</tr>
<tr>
<td><i class="conum" data-value="2"></i><b>2</b></td>
<td>Add the dependency to <code>spring-cloud-starter-zipkin</code>. That way, all nested dependencies get downloaded.</td>
</tr>
<tr>
<td><i class="conum" data-value="3"></i><b>3</b></td>
<td>To automatically configure RabbitMQ, add the <code>spring-rabbit</code> dependency.</td>
</tr>
</table>
</div>
<div class="listingblock secondary">
<div class="title">Gradle</div>
<div class="content">
<pre class="highlightjs highlight"><code class="language-groovy hljs" data-lang="groovy">dependencyManagement { <i class="conum" data-value="1"></i><b>(1)</b>
imports {
mavenBom "org.springframework.cloud:spring-cloud-dependencies:${releaseTrainVersion}"
}
}
dependencies {
compile "org.springframework.cloud:spring-cloud-starter-zipkin" <i class="conum" data-value="2"></i><b>(2)</b>
compile "org.springframework.amqp:spring-rabbit" <i class="conum" data-value="3"></i><b>(3)</b>
}</code></pre>
</div>
</div>
<div class="colist arabic">
<table>
<tr>
<td><i class="conum" data-value="1"></i><b>1</b></td>
<td>We recommend that you add the dependency management through the Spring BOM so that you need not manage versions yourself.</td>
</tr>
<tr>
<td><i class="conum" data-value="2"></i><b>2</b></td>
<td>Add the dependency to <code>spring-cloud-starter-zipkin</code>. That way, all nested dependencies get downloaded.</td>
</tr>
<tr>
<td><i class="conum" data-value="3"></i><b>3</b></td>
<td>To automatically configure RabbitMQ, add the <code>spring-rabbit</code> dependency.</td>
</tr>
</table>
</div>
</div>
</div>
<div class="sect2">
<h3 id="_overriding_the_auto_configuration_of_zipkin"><a class="link" href="#_overriding_the_auto_configuration_of_zipkin">Overriding the auto-configuration of Zipkin</a></h3>
<div class="paragraph">
<p>Spring Cloud Sleuth supports sending traces to multiple tracing systems as of version 2.1.0.
In order to get this to work, every tracing system needs to have a <code>Reporter&lt;Span&gt;</code> and <code>Sender</code>.
If you want to override the provided beans you need to give them a specific name.
To do this you can use respectively <code>ZipkinAutoConfiguration.REPORTER_BEAN_NAME</code> and <code>ZipkinAutoConfiguration.SENDER_BEAN_NAME</code>.</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@Configuration
protected static class MyConfig {
@Bean(ZipkinAutoConfiguration.REPORTER_BEAN_NAME)
Reporter&lt;zipkin2.Span&gt; myReporter() {
return AsyncReporter.create(mySender());
}
@Bean(ZipkinAutoConfiguration.SENDER_BEAN_NAME)
MySender mySender() {
return new MySender();
}
static class MySender extends Sender {
private boolean spanSent = false;
boolean isSpanSent() {
return this.spanSent;
}
@Override
public Encoding encoding() {
return Encoding.JSON;
}
@Override
public int messageMaxBytes() {
return Integer.MAX_VALUE;
}
@Override
public int messageSizeInBytes(List&lt;byte[]&gt; encodedSpans) {
return encoding().listSizeInBytes(encodedSpans);
}
@Override
public Call&lt;Void&gt; sendSpans(List&lt;byte[]&gt; encodedSpans) {
this.spanSent = true;
return Call.create(null);
}
}
}</code></pre>
</div>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_additional_resources"><a class="link" href="#_additional_resources">Additional Resources</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>You can watch a video of <a href="https://twitter.com/reshmi9k">Reshmi Krishna</a> and <a href="https://twitter.com/mgrzejszczak">Marcin Grzejszczak</a> talking about Spring Cloud
Sleuth and Zipkin <a href="https://content.pivotal.io/springone-platform-2017/distributed-tracing-latency-analysis-for-your-microservices-grzejszczak-krishna">by clicking here</a>.</p>
</div>
<div class="paragraph">
<p>You can check different setups of Sleuth and Brave <a href="https://github.com/openzipkin/sleuth-webmvc-example">in the openzipkin/sleuth-webmvc-example repository</a>.</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_features"><a class="link" href="#_features">Features</a></h2>
<div class="sectionbody">
<div class="ulist">
<ul>
<li>
<p>Adds trace and span IDs to the Slf4J MDC, so you can extract all the logs from a given trace or span in a log aggregator, as shown in the following example logs:</p>
<div class="listingblock">
<div class="content">
<pre>2016-02-02 15:30:57.902 INFO [bar,6bfd228dc00d216b,6bfd228dc00d216b,false] 23030 --- [nio-8081-exec-3] ...
2016-02-02 15:30:58.372 ERROR [bar,6bfd228dc00d216b,6bfd228dc00d216b,false] 23030 --- [nio-8081-exec-3] ...
2016-02-02 15:31:01.936 INFO [bar,46ab0d418373cbc9,46ab0d418373cbc9,false] 23030 --- [nio-8081-exec-4] ...</pre>
</div>
</div>
<div class="paragraph">
<p>Notice the <code>[appname,traceId,spanId,exportable]</code> entries from the MDC:</p>
</div>
<div class="ulist">
<ul>
<li>
<p><strong><code>spanId</code></strong>: The ID of a specific operation that took place.</p>
</li>
<li>
<p><strong><code>appname</code></strong>: The name of the application that logged the span.</p>
</li>
<li>
<p><strong><code>traceId</code></strong>: The ID of the latency graph that contains the span.</p>
</li>
<li>
<p><strong><code>exportable</code></strong>: Whether the log should be exported to Zipkin.
When would you like the span not to be exportable?
When you want to wrap some operation in a Span and have it written to the logs only.</p>
</li>
</ul>
</div>
</li>
<li>
<p>Provides an abstraction over common distributed tracing data models: traces, spans (forming a DAG), annotations, and key-value annotations.
Spring Cloud Sleuth is loosely based on HTrace but is compatible with Zipkin (Dapper).</p>
</li>
<li>
<p>Sleuth records timing information to aid in latency analysis.
By using sleuth, you can pinpoint causes of latency in your applications.</p>
</li>
<li>
<p>Sleuth is written to not log too much and to not cause your production application to crash.
To that end, Sleuth:</p>
<div class="ulist">
<ul>
<li>
<p>Propagates structural data about your call graph in-band and the rest out-of-band.</p>
</li>
<li>
<p>Includes opinionated instrumentation of layers such as HTTP.</p>
</li>
<li>
<p>Includes a sampling policy to manage volume.</p>
</li>
<li>
<p>Can report to a Zipkin system for query and visualization.</p>
</li>
</ul>
</div>
</li>
<li>
<p>Instruments common ingress and egress points from Spring applications (servlet filter, async endpoints, rest template, scheduled actions, message channels, Zuul filters, and Feign client).</p>
</li>
<li>
<p>Sleuth includes default logic to join a trace across HTTP or messaging boundaries.
For example, HTTP propagation works over Zipkin-compatible request headers.</p>
</li>
<li>
<p>Sleuth can propagate context (also known as baggage) between processes.
Consequently, if you set a baggage element on a Span, it is sent downstream to other processes over either HTTP or messaging.</p>
</li>
<li>
<p>Provides a way to create or continue spans and add tags and logs through annotations.</p>
</li>
<li>
<p>If <code>spring-cloud-sleuth-zipkin</code> is on the classpath, the app generates and collects Zipkin-compatible traces.
By default, it sends them over HTTP to a Zipkin server on localhost (port 9411).
You can configure the location of the service by setting <code>spring.zipkin.baseUrl</code>.</p>
<div class="ulist">
<ul>
<li>
<p>If you depend on <code>spring-rabbit</code>, your app sends traces to a RabbitMQ broker instead of HTTP.</p>
</li>
<li>
<p>If you depend on <code>spring-kafka</code>, and set <code>spring.zipkin.sender.type: kafka</code>, your app sends traces to a Kafka broker instead of HTTP.</p>
</li>
</ul>
</div>
</li>
</ul>
</div>
<div class="admonitionblock caution">
<table>
<tr>
<td class="icon">
<i class="fa icon-caution" title="Caution"></i>
</td>
<td class="content">
<code>spring-cloud-sleuth-stream</code> is deprecated and should no longer be used.
</td>
</tr>
</table>
</div>
<div class="ulist">
<ul>
<li>
<p>Spring Cloud Sleuth is <a href="https://opentracing.io/">OpenTracing</a> compatible.</p>
</li>
</ul>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<i class="fa icon-note" title="Note"></i>
</td>
<td class="content">
The SLF4J MDC is always set and logback users immediately see the trace and span IDs in logs per the example
shown earlier.
Other logging systems have to configure their own formatter to get the same result.
The default is as follows:
<code>logging.pattern.level</code> set to <code>%5p [${spring.zipkin.service.name:${spring.application.name:-}},%X{X-B3-TraceId:-},%X{X-B3-SpanId:-},%X{X-Span-Export:-}]</code>
(this is a Spring Boot feature for logback users).
If you do not use SLF4J, this pattern is NOT automatically applied.
</td>
</tr>
</table>
</div>
<div class="sect2">
<h3 id="_introduction_to_brave"><a class="link" href="#_introduction_to_brave">Introduction to Brave</a></h3>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
Starting with version <code>2.0.0</code>, Spring Cloud Sleuth uses
<a href="https://github.com/openzipkin/brave">Brave</a> as the tracing library.
For your convenience, we embed part of the Brave&#8217;s docs here.
</td>
</tr>
</table>
</div>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
In the vast majority of cases you need to just use the <code>Tracer</code>
or <code>SpanCustomizer</code> beans from Brave that Sleuth provides. The documentation below contains
a high overview of what Brave is and how it works.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>Brave is a library used to capture and report latency information about distributed operations to Zipkin.
Most users do not use Brave directly. They use libraries or frameworks rather than employ Brave on their behalf.</p>
</div>
<div class="paragraph">
<p>This module includes a tracer that creates and joins spans that model the latency of potentially distributed work.
It also includes libraries to propagate the trace context over network boundaries (for example, with HTTP headers).</p>
</div>
<div class="sect3">
<h4 id="_tracing"><a class="link" href="#_tracing">Tracing</a></h4>
<div class="paragraph">
<p>Most importantly, you need a <code>brave.Tracer</code>, configured to <a href="https://github.com/openzipkin/zipkin-reporter-java">report to Zipkin</a>.</p>
</div>
<div class="paragraph">
<p>The following example setup sends trace data (spans) to Zipkin over HTTP (as opposed to Kafka):</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">class MyClass {
private final Tracer tracer;
// Tracer will be autowired
MyClass(Tracer tracer) {
this.tracer = tracer;
}
void doSth() {
Span span = tracer.newTrace().name("encode").start();
// ...
}
}</code></pre>
</div>
</div>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
If your span contains a name longer than 50 chars, then that name is truncated to 50 chars.
Your names have to be explicit and concrete.
Big names lead to latency issues and sometimes even thrown exceptions.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>The tracer creates and joins spans that model the latency of potentially distributed work.
It can employ sampling to reduce overhead during the process, to reduce the amount of data sent to Zipkin, or both.</p>
</div>
<div class="paragraph">
<p>Spans returned by a tracer report data to Zipkin when finished or do nothing if unsampled.
After starting a span, you can annotate events of interest or add tags containing details or lookup keys.</p>
</div>
<div class="paragraph">
<p>Spans have a context that includes trace identifiers that place the span at the correct spot in the tree representing the distributed operation.</p>
</div>
</div>
<div class="sect3">
<h4 id="_local_tracing"><a class="link" href="#_local_tracing">Local Tracing</a></h4>
<div class="paragraph">
<p>When tracing code that never leaves your process, run it inside a scoped span.</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@Autowired Tracer tracer;
// Start a new trace or a span within an existing trace representing an operation
ScopedSpan span = tracer.startScopedSpan("encode");
try {
// The span is in "scope" meaning downstream code such as loggers can see trace IDs
return encoder.encode();
} catch (RuntimeException | Error e) {
span.error(e); // Unless you handle exceptions, you might not know the operation failed!
throw e;
} finally {
span.finish(); // always finish the span
}</code></pre>
</div>
</div>
<div class="paragraph">
<p>When you need more features, or finer control, use the <code>Span</code> type:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@Autowired Tracer tracer;
// Start a new trace or a span within an existing trace representing an operation
Span span = tracer.nextSpan().name("encode").start();
// Put the span in "scope" so that downstream code such as loggers can see trace IDs
try (SpanInScope ws = tracer.withSpanInScope(span)) {
return encoder.encode();
} catch (RuntimeException | Error e) {
span.error(e); // Unless you handle exceptions, you might not know the operation failed!
throw e;
} finally {
span.finish(); // note the scope is independent of the span. Always finish a span.
}</code></pre>
</div>
</div>
<div class="paragraph">
<p>Both of the above examples report the exact same span on finish!</p>
</div>
<div class="paragraph">
<p>In the above example, the span will be either a new root span or the
next child in an existing trace.</p>
</div>
</div>
<div class="sect3">
<h4 id="_customizing_spans"><a class="link" href="#_customizing_spans">Customizing Spans</a></h4>
<div class="paragraph">
<p>Once you have a span, you can add tags to it.
The tags can be used as lookup keys or details.
For example, you might add a tag with your runtime version, as shown in the following example:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">span.tag("clnt/finagle.version", "6.36.0");</code></pre>
</div>
</div>
<div class="paragraph">
<p>When exposing the ability to customize spans to third parties, prefer <code>brave.SpanCustomizer</code> as opposed to <code>brave.Span</code>.
The former is simpler to understand and test and does not tempt users with span lifecycle hooks.</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">interface MyTraceCallback {
void request(Request request, SpanCustomizer customizer);
}</code></pre>
</div>
</div>
<div class="paragraph">
<p>Since <code>brave.Span</code> implements <code>brave.SpanCustomizer</code>, you can pass it to users, as shown in the following example:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">for (MyTraceCallback callback : userCallbacks) {
callback.request(request, span);
}</code></pre>
</div>
</div>
</div>
<div class="sect3">
<h4 id="_implicitly_looking_up_the_current_span"><a class="link" href="#_implicitly_looking_up_the_current_span">Implicitly Looking up the Current Span</a></h4>
<div class="paragraph">
<p>Sometimes, you do not know if a trace is in progress or not, and you do not want users to do null checks.
<code>brave.CurrentSpanCustomizer</code> handles this problem by adding data to any span that&#8217;s in progress or drops, as shown in the following example:</p>
</div>
<div class="paragraph">
<p>Ex.</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">// The user code can then inject this without a chance of it being null.
@Autowired SpanCustomizer span;
void userCode() {
span.annotate("tx.started");
...
}</code></pre>
</div>
</div>
</div>
<div class="sect3">
<h4 id="_rpc_tracing"><a class="link" href="#_rpc_tracing">RPC tracing</a></h4>
<div class="admonitionblock tip">
<table>
<tr>
<td class="icon">
<i class="fa icon-tip" title="Tip"></i>
</td>
<td class="content">
Check for <a href="https://github.com/openzipkin/brave/tree/master/instrumentation">instrumentation written here</a> and <a href="https://zipkin.io/pages/existing_instrumentations.html">Zipkin&#8217;s list</a> before rolling your own RPC instrumentation.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>RPC tracing is often done automatically by interceptors. Behind the scenes, they add tags and events that relate to their role in an RPC operation.</p>
</div>
<div class="paragraph">
<p>The following example shows how to add a client span:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@Autowired Tracing tracing;
@Autowired Tracer tracer;
// before you send a request, add metadata that describes the operation
span = tracer.nextSpan().name(service + "/" + method).kind(CLIENT);
span.tag("myrpc.version", "1.0.0");
span.remoteServiceName("backend");
span.remoteIpAndPort("172.3.4.1", 8108);
// Add the trace context to the request, so it can be propagated in-band
tracing.propagation().injector(Request::addHeader)
.inject(span.context(), request);
// when the request is scheduled, start the span
span.start();
// if there is an error, tag the span
span.tag("error", error.getCode());
// or if there is an exception
span.error(exception);
// when the response is complete, finish the span
span.finish();</code></pre>
</div>
</div>
<div class="sect4">
<h5 id="_one_way_tracing"><a class="link" href="#_one_way_tracing">One-Way tracing</a></h5>
<div class="paragraph">
<p>Sometimes, you need to model an asynchronous operation where there is a
request but no response. In normal RPC tracing, you use <code>span.finish()</code>
to indicate that the response was received. In one-way tracing, you use
<code>span.flush()</code> instead, as you do not expect a response.</p>
</div>
<div class="paragraph">
<p>The following example shows how a client might model a one-way operation:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@Autowired Tracing tracing;
@Autowired Tracer tracer;
// start a new span representing a client request
oneWaySend = tracer.nextSpan().name(service + "/" + method).kind(CLIENT);
// Add the trace context to the request, so it can be propagated in-band
tracing.propagation().injector(Request::addHeader)
.inject(oneWaySend.context(), request);
// fire off the request asynchronously, totally dropping any response
request.execute();
// start the client side and flush instead of finish
oneWaySend.start().flush();</code></pre>
</div>
</div>
<div class="paragraph">
<p>The following example shows how a server might handle a one-way operation:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@Autowired Tracing tracing;
@Autowired Tracer tracer;
// pull the context out of the incoming request
extractor = tracing.propagation().extractor(Request::getHeader);
// convert that context to a span which you can name and add tags to
oneWayReceive = nextSpan(tracer, extractor.extract(request))
.name("process-request")
.kind(SERVER)
... add tags etc.
// start the server side and flush instead of finish
oneWayReceive.start().flush();
// you should not modify this span anymore as it is complete. However,
// you can create children to represent follow-up work.
next = tracer.newSpan(oneWayReceive.context()).name("step2").start();</code></pre>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_sampling"><a class="link" href="#_sampling">Sampling</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>Sampling may be employed to reduce the data collected and reported out of process.
When a span is not sampled, it adds no overhead (a noop).</p>
</div>
<div class="paragraph">
<p>Sampling is an up-front decision, meaning that the decision to report data is made at the first operation in a trace and that decision is propagated downstream.</p>
</div>
<div class="paragraph">
<p>By default, a global sampler applies a single rate to all traced operations.
<code>Tracer.Builder.sampler</code> controls this setting, and it defaults to tracing every request.</p>
</div>
<div class="sect2">
<h3 id="_declarative_sampling"><a class="link" href="#_declarative_sampling">Declarative sampling</a></h3>
<div class="paragraph">
<p>Some applications need to sample based on the type or annotations of a java method.</p>
</div>
<div class="paragraph">
<p>Most users use a framework interceptor to automate this sort of policy.
The following example shows how that might work internally:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@Autowired Tracer tracer;
// derives a sample rate from an annotation on a java method
DeclarativeSampler&lt;Traced&gt; sampler = DeclarativeSampler.create(Traced::sampleRate);
@Around("@annotation(traced)")
public Object traceThing(ProceedingJoinPoint pjp, Traced traced) throws Throwable {
// When there is no trace in progress, this decides using an annotation
Sampler decideUsingAnnotation = declarativeSampler.toSampler(traced);
Tracer tracer = tracer.withSampler(decideUsingAnnotation);
// This code looks the same as if there was no declarative override
ScopedSpan span = tracer.startScopedSpan(spanName(pjp));
try {
return pjp.proceed();
} catch (RuntimeException | Error e) {
span.error(e);
throw e;
} finally {
span.finish();
}
}</code></pre>
</div>
</div>
</div>
<div class="sect2">
<h3 id="_custom_sampling"><a class="link" href="#_custom_sampling">Custom sampling</a></h3>
<div class="paragraph">
<p>Depending on what the operation is, you may want to apply different policies.
For example, you might not want to trace requests to static resources such as images, or you might want to trace all requests to a new api.</p>
</div>
<div class="paragraph">
<p>Most users use a framework interceptor to automate this sort of policy.
The following example shows how that might work internally:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@Autowired Tracer tracer;
@Autowired Sampler fallback;
Span nextSpan(final Request input) {
Sampler requestBased = Sampler() {
@Override public boolean isSampled(long traceId) {
if (input.url().startsWith("/experimental")) {
return true;
} else if (input.url().startsWith("/static")) {
return false;
}
return fallback.isSampled(traceId);
}
};
return tracer.withSampler(requestBased).nextSpan();
}</code></pre>
</div>
</div>
</div>
<div class="sect2">
<h3 id="_sampling_in_spring_cloud_sleuth"><a class="link" href="#_sampling_in_spring_cloud_sleuth">Sampling in Spring Cloud Sleuth</a></h3>
<div class="paragraph">
<p>By default Spring Cloud Sleuth sets all spans to non-exportable.
That means that traces appear in logs but not in any remote store.
For testing the default is often enough, and it probably is all you need if you use only the logs (for example, with an ELK aggregator).
If you export span data to Zipkin, there is also an <code>Sampler.ALWAYS_SAMPLE</code> setting that exports everything, <code>RateLimitingSampler</code> setting that samples X transactions per second (defaults to <code>1000</code>) or <code>ProbabilityBasedSampler</code> setting that samples a fixed fraction of spans.</p>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<i class="fa icon-note" title="Note"></i>
</td>
<td class="content">
The <code>RateLimitingSampler</code> is the default if you use <code>spring-cloud-sleuth-zipkin</code>.
You can configure the rate limit by setting <code>spring.sleuth.sampler.rate</code>.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>A sampler can be installed by creating a bean definition, as shown in the following example:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@Bean
public Sampler defaultSampler() {
return Sampler.ALWAYS_SAMPLE;
}</code></pre>
</div>
</div>
<div class="admonitionblock tip">
<table>
<tr>
<td class="icon">
<i class="fa icon-tip" title="Tip"></i>
</td>
<td class="content">
You can set the HTTP header <code>X-B3-Flags</code> to <code>1</code>, or, when doing messaging, you can set the <code>spanFlags</code> header to <code>1</code>.
Doing so forces the current span to be exportable regardless of the sampling decision.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>In order to use the rate-limited sampler set the <code>spring.sleuth.sampler.rate</code> property to choose an amount of traces to accept on a per-second interval. The minimum number is 0 and the max is 2,147,483,647 (max int).</p>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_propagation"><a class="link" href="#_propagation">Propagation</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>Propagation is needed to ensure activities originating from the same root are collected together in the same trace.
The most common propagation approach is to copy a trace context from a client by sending an RPC request to a server receiving it.</p>
</div>
<div class="paragraph">
<p>For example, when a downstream HTTP call is made, its trace context is encoded as request headers and sent along with it, as shown in the following image:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code> Client Span Server Span
┌──────────────────┐ ┌──────────────────┐
│ │ │ │
│ TraceContext │ Http Request Headers │ TraceContext │
│ ┌──────────────┐ │ ┌───────────────────┐ │ ┌──────────────┐ │
│ │ TraceId │ │ │ X─B3─TraceId │ │ │ TraceId │ │
│ │ │ │ │ │ │ │ │ │
│ │ ParentSpanId │ │ Extract │ X─B3─ParentSpanId │ Inject │ │ ParentSpanId │ │
│ │ ├─┼─────────&gt;│ ├────────┼&gt;│ │ │
│ │ SpanId │ │ │ X─B3─SpanId │ │ │ SpanId │ │
│ │ │ │ │ │ │ │ │ │
│ │ Sampled │ │ │ X─B3─Sampled │ │ │ Sampled │ │
│ └──────────────┘ │ └───────────────────┘ │ └──────────────┘ │
│ │ │ │
└──────────────────┘ └──────────────────┘</code></pre>
</div>
</div>
<div class="paragraph">
<p>The names above are from <a href="https://github.com/openzipkin/b3-propagation">B3 Propagation</a>, which is built-in to Brave and has implementations in many languages and frameworks.</p>
</div>
<div class="paragraph">
<p>Most users use a framework interceptor to automate propagation.
The next two examples show how that might work for a client and a server.</p>
</div>
<div class="paragraph">
<p>The following example shows how client-side propagation might work:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@Autowired Tracing tracing;
// configure a function that injects a trace context into a request
injector = tracing.propagation().injector(Request.Builder::addHeader);
// before a request is sent, add the current span's context to it
injector.inject(span.context(), request);</code></pre>
</div>
</div>
<div class="paragraph">
<p>The following example shows how server-side propagation might work:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@Autowired Tracing tracing;
@Autowired Tracer tracer;
// configure a function that extracts the trace context from a request
extractor = tracing.propagation().extractor(Request::getHeader);
// when a server receives a request, it joins or starts a new trace
span = tracer.nextSpan(extractor.extract(request));</code></pre>
</div>
</div>
<div class="sect2">
<h3 id="_propagating_extra_fields"><a class="link" href="#_propagating_extra_fields">Propagating extra fields</a></h3>
<div class="paragraph">
<p>Sometimes you need to propagate extra fields, such as a request ID or an alternate trace context.
For example, if you are in a Cloud Foundry environment, you might want to pass the request ID, as shown in the following example:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">// when you initialize the builder, define the extra field you want to propagate
Tracing.newBuilder().propagationFactory(
ExtraFieldPropagation.newFactory(B3Propagation.FACTORY, "x-vcap-request-id")
);
// later, you can tag that request ID or use it in log correlation
requestId = ExtraFieldPropagation.get("x-vcap-request-id");</code></pre>
</div>
</div>
<div class="paragraph">
<p>You may also need to propagate a trace context that you are not using.
For example, you may be in an Amazon Web Services environment but not be reporting data to X-Ray.
To ensure X-Ray can co-exist correctly, pass-through its tracing header, as shown in the following example:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">tracingBuilder.propagationFactory(
ExtraFieldPropagation.newFactory(B3Propagation.FACTORY, "x-amzn-trace-id")
);</code></pre>
</div>
</div>
<div class="admonitionblock tip">
<table>
<tr>
<td class="icon">
<i class="fa icon-tip" title="Tip"></i>
</td>
<td class="content">
In Spring Cloud Sleuth all elements of the tracing builder <code>Tracing.newBuilder()</code>
are defined as beans. So if you want to pass a custom <code>PropagationFactory</code>, it&#8217;s enough
for you to create a bean of that type and we will set it in the <code>Tracing</code> bean.
</td>
</tr>
</table>
</div>
<div class="sect3">
<h4 id="prefixed-fields"><a class="link" href="#prefixed-fields">Prefixed fields</a></h4>
<div class="paragraph">
<p>If they follow a common pattern, you can also prefix fields.
The following example shows how to propagate <code>x-vcap-request-id</code> the field as-is but send the <code>country-code</code> and <code>user-id</code> fields on the wire as <code>x-baggage-country-code</code> and <code>x-baggage-user-id</code>, respectively:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">Tracing.newBuilder().propagationFactory(
ExtraFieldPropagation.newFactoryBuilder(B3Propagation.FACTORY)
.addField("x-vcap-request-id")
.addPrefixedFields("x-baggage-", Arrays.asList("country-code", "user-id"))
.build()
);</code></pre>
</div>
</div>
<div class="paragraph">
<p>Later, you can call the following code to affect the country code of the current trace context:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">ExtraFieldPropagation.set("x-country-code", "FO");
String countryCode = ExtraFieldPropagation.get("x-country-code");</code></pre>
</div>
</div>
<div class="paragraph">
<p>Alternatively, if you have a reference to a trace context, you can use it explicitly, as shown in the following example:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">ExtraFieldPropagation.set(span.context(), "x-country-code", "FO");
String countryCode = ExtraFieldPropagation.get(span.context(), "x-country-code");</code></pre>
</div>
</div>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
A difference from previous versions of Sleuth is that, with Brave, you must pass the list of baggage keys.
There are two properties to achieve this.
With the <code>spring.sleuth.baggage-keys</code>, you set keys that get prefixed with <code>baggage-</code> for HTTP calls and <code>baggage_</code> for messaging.
You can also use the <code>spring.sleuth.propagation-keys</code> property to pass a list of prefixed keys that are whitelisted without any prefix.
Notice that there&#8217;s no <code>x-</code> in front of the header keys.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>In order to automatically set the baggage values to Slf4j&#8217;s MDC, you have to set
the <code>spring.sleuth.log.slf4j.whitelisted-mdc-keys</code> property with a list of whitelisted
baggage and propagation keys. E.g. <code>spring.sleuth.log.slf4j.whitelisted-mdc-keys=foo</code> will set the value of the <code>foo</code> baggage into MDC.</p>
</div>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
Remember that adding entries to MDC can drastically decrease the performance of your application!
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>If you want to add the baggage entries as tags, to make it possible to search for spans via the baggage entries, you can set the value of
<code>spring.sleuth.propagation.tag.whitelisted-keys</code> with a list of whitelisted baggage keys. To disable the feature you have to pass the <code>spring.sleuth.propagation.tag.enabled=false</code> property.</p>
</div>
</div>
<div class="sect3">
<h4 id="_extracting_a_propagated_context"><a class="link" href="#_extracting_a_propagated_context">Extracting a Propagated Context</a></h4>
<div class="paragraph">
<p>The <code>TraceContext.Extractor&lt;C&gt;</code> reads trace identifiers and sampling status from an incoming request or message.
The carrier is usually a request object or headers.</p>
</div>
<div class="paragraph">
<p>This utility is used in standard instrumentation (such as <code>HttpServerHandler</code>) but can also be used for custom RPC or messaging code.</p>
</div>
<div class="paragraph">
<p><code>TraceContextOrSamplingFlags</code> is usually used only with <code>Tracer.nextSpan(extracted)</code>, unless you are
sharing span IDs between a client and a server.</p>
</div>
</div>
<div class="sect3">
<h4 id="_sharing_span_ids_between_client_and_server"><a class="link" href="#_sharing_span_ids_between_client_and_server">Sharing span IDs between Client and Server</a></h4>
<div class="paragraph">
<p>A normal instrumentation pattern is to create a span representing the server side of an RPC.
<code>Extractor.extract</code> might return a complete trace context when applied to an incoming client request.
<code>Tracer.joinSpan</code> attempts to continue this trace, using the same span ID if supported or creating a child span
if not. When the span ID is shared, the reported data includes a flag saying so.</p>
</div>
<div class="paragraph">
<p>The following image shows an example of B3 propagation:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code> ┌───────────────────┐ ┌───────────────────┐
Incoming Headers │ TraceContext │ │ TraceContext │
┌───────────────────┐(extract)│ ┌───────────────┐ │(join)│ ┌───────────────┐ │
│ X─B3-TraceId │─────────┼─┼&gt; TraceId │ │──────┼─┼&gt; TraceId │ │
│ │ │ │ │ │ │ │ │ │
│ X─B3-ParentSpanId │─────────┼─┼&gt; ParentSpanId │ │──────┼─┼&gt; ParentSpanId │ │
│ │ │ │ │ │ │ │ │ │
│ X─B3-SpanId │─────────┼─┼&gt; SpanId │ │──────┼─┼&gt; SpanId │ │
└───────────────────┘ │ │ │ │ │ │ │ │
│ │ │ │ │ │ Shared: true │ │
│ └───────────────┘ │ │ └───────────────┘ │
└───────────────────┘ └───────────────────┘</code></pre>
</div>
</div>
<div class="paragraph">
<p>Some propagation systems forward only the parent span ID, detected when <code>Propagation.Factory.supportsJoin() == false</code>.
In this case, a new span ID is always provisioned, and the incoming context determines the parent ID.</p>
</div>
<div class="paragraph">
<p>The following image shows an example of AWS propagation:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code> ┌───────────────────┐ ┌───────────────────┐
x-amzn-trace-id │ TraceContext │ │ TraceContext │
┌───────────────────┐(extract)│ ┌───────────────┐ │(join)│ ┌───────────────┐ │
│ Root │─────────┼─┼&gt; TraceId │ │──────┼─┼&gt; TraceId │ │
│ │ │ │ │ │ │ │ │ │
│ Parent │─────────┼─┼&gt; SpanId │ │──────┼─┼&gt; ParentSpanId │ │
└───────────────────┘ │ └───────────────┘ │ │ │ │ │
└───────────────────┘ │ │ SpanId: New │ │
│ └───────────────┘ │
└───────────────────┘</code></pre>
</div>
</div>
<div class="paragraph">
<p>Note: Some span reporters do not support sharing span IDs.
For example, if you set <code>Tracing.Builder.spanReporter(amazonXrayOrGoogleStackdrive)</code>, you should disable join by setting <code>Tracing.Builder.supportsJoin(false)</code>.
Doing so forces a new child span on <code>Tracer.joinSpan()</code>.</p>
</div>
</div>
<div class="sect3">
<h4 id="_implementing_propagation"><a class="link" href="#_implementing_propagation">Implementing Propagation</a></h4>
<div class="paragraph">
<p><code>TraceContext.Extractor&lt;C&gt;</code> is implemented by a <code>Propagation.Factory</code> plugin.
Internally, this code creates the union type, <code>TraceContextOrSamplingFlags</code>, with one of the following:
* <code>TraceContext</code> if trace and span IDs were present.
* <code>TraceIdContext</code> if a trace ID was present but span IDs were not present.
* <code>SamplingFlags</code> if no identifiers were present.</p>
</div>
<div class="paragraph">
<p>Some <code>Propagation</code> implementations carry extra data from the point of extraction (for example, reading incoming headers) to injection (for example, writing outgoing headers).
For example, it might carry a request ID.
When implementations have extra data, they handle it as follows:
* If a <code>TraceContext</code> were extracted, add the extra data as <code>TraceContext.extra()</code>.
* Otherwise, add it as <code>TraceContextOrSamplingFlags.extra()</code>, which <code>Tracer.nextSpan</code> handles.</p>
</div>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_current_tracing_component"><a class="link" href="#_current_tracing_component">Current Tracing Component</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>Brave supports a "<code>current tracing component</code>" concept, which should only be used when you have no other way to get a reference.
This was made for JDBC connections, as they often initialize prior to the tracing component.</p>
</div>
<div class="paragraph">
<p>The most recent tracing component instantiated is available through <code>Tracing.current()</code>.
You can also use <code>Tracing.currentTracer()</code> to get only the tracer.
If you use either of these methods, do not cache the result.
Instead, look them up each time you need them.</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_current_span"><a class="link" href="#_current_span">Current Span</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>Brave supports a "<code>current span</code>" concept which represents the in-flight operation.
You can use <code>Tracer.currentSpan()</code> to add custom tags to a span and <code>Tracer.nextSpan()</code> to create a child of whatever is in-flight.</p>
</div>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
In Sleuth, you can autowire the <code>Tracer</code> bean to retrieve the current span via
<code>tracer.currentSpan()</code> method. To retrieve the current context just call
<code>tracer.currentSpan().context()</code>. To get the current trace id as String
you can use the <code>traceIdString()</code> method like this: <code>tracer.currentSpan().context().traceIdString()</code>.
</td>
</tr>
</table>
</div>
<div class="sect2">
<h3 id="_setting_a_span_in_scope_manually"><a class="link" href="#_setting_a_span_in_scope_manually">Setting a span in scope manually</a></h3>
<div class="paragraph">
<p>When writing new instrumentation, it is important to place a span you created in scope as the current span.
Not only does doing so let users access it with <code>Tracer.currentSpan()</code>, but it also allows customizations such as SLF4J MDC to see the current trace IDs.</p>
</div>
<div class="paragraph">
<p><code>Tracer.withSpanInScope(Span)</code> facilitates this and is most conveniently employed by using the try-with-resources idiom.
Whenever external code might be invoked (such as proceeding an interceptor or otherwise), place the span in scope, as shown in the following example:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@Autowired Tracer tracer;
try (SpanInScope ws = tracer.withSpanInScope(span)) {
return inboundRequest.invoke();
} finally { // note the scope is independent of the span
span.finish();
}</code></pre>
</div>
</div>
<div class="paragraph">
<p>In edge cases, you may need to clear the current span temporarily (for example, launching a task that should not be associated with the current request). To do tso, pass null to <code>withSpanInScope</code>, as shown in the following example:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@Autowired Tracer tracer;
try (SpanInScope cleared = tracer.withSpanInScope(null)) {
startBackgroundThread();
}</code></pre>
</div>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_instrumentation"><a class="link" href="#_instrumentation">Instrumentation</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>Spring Cloud Sleuth automatically instruments all your Spring applications, so you should not have to do anything to activate it.
The instrumentation is added by using a variety of technologies according to the stack that is available. For example, for a servlet web application, we use a <code>Filter</code>, and, for Spring Integration, we use <code>ChannelInterceptors</code>.</p>
</div>
<div class="paragraph">
<p>You can customize the keys used in span tags.
To limit the volume of span data, an HTTP request is, by default, tagged only with a handful of metadata, such as the status code, the host, and the URL.
You can add request headers by configuring <code>spring.sleuth.keys.http.headers</code> (a list of header names).</p>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<i class="fa icon-note" title="Note"></i>
</td>
<td class="content">
Tags are collected and exported only if there is a <code>Sampler</code> that allows it. By default, there is no such <code>Sampler</code>, to ensure that there is no danger of accidentally collecting too much data without configuring something).
</td>
</tr>
</table>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_span_lifecycle"><a class="link" href="#_span_lifecycle">Span lifecycle</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>You can do the following operations on the Span by means of <code>brave.Tracer</code>:</p>
</div>
<div class="ulist">
<ul>
<li>
<p><a href="#creating-and-finishing-spans">start</a>: When you start a span, its name is assigned and the start timestamp is recorded.</p>
</li>
<li>
<p><a href="#creating-and-finishing-spans">close</a>: The span gets finished (the end time of the span is recorded) and, if the span is sampled, it is eligible for collection (for example, to Zipkin).</p>
</li>
<li>
<p><a href="#continuing-spans">continue</a>: A new instance of span is created.
It is a copy of the one that it continues.</p>
</li>
<li>
<p><a href="#continuing-spans">detach</a>: The span does not get stopped or closed.
It only gets removed from the current thread.</p>
</li>
<li>
<p><a href="#creating-spans-with-explicit-parent">create with explicit parent</a>: You can create a new span and set an explicit parent for it.</p>
</li>
</ul>
</div>
<div class="admonitionblock tip">
<table>
<tr>
<td class="icon">
<i class="fa icon-tip" title="Tip"></i>
</td>
<td class="content">
Spring Cloud Sleuth creates an instance of <code>Tracer</code> for you. In order to use it, you can autowire it.
</td>
</tr>
</table>
</div>
<div class="sect2">
<h3 id="creating-and-finishing-spans"><a class="link" href="#creating-and-finishing-spans">Creating and finishing spans</a></h3>
<div class="paragraph">
<p>You can manually create spans by using the <code>Tracer</code>, as shown in the following example:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">// Start a span. If there was a span present in this thread it will become
// the `newSpan`'s parent.
Span newSpan = this.tracer.nextSpan().name("calculateTax");
try (Tracer.SpanInScope ws = this.tracer.withSpanInScope(newSpan.start())) {
// ...
// You can tag a span
newSpan.tag("taxValue", taxValue);
// ...
// You can log an event on a span
newSpan.annotate("taxCalculated");
}
finally {
// Once done remember to finish the span. This will allow collecting
// the span to send it to Zipkin
newSpan.finish();
}</code></pre>
</div>
</div>
<div class="paragraph">
<p>In the preceding example, we could see how to create a new instance of the span.
If there is already a span in this thread, it becomes the parent of the new span.</p>
</div>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
Always clean after you create a span. Also, always finish any span that you want to send to Zipkin.
</td>
</tr>
</table>
</div>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
If your span contains a name greater than 50 chars, that name is truncated to 50 chars.
Your names have to be explicit and concrete. Big names lead to latency issues and sometimes even exceptions.
</td>
</tr>
</table>
</div>
</div>
<div class="sect2">
<h3 id="continuing-spans"><a class="link" href="#continuing-spans">Continuing Spans</a></h3>
<div class="paragraph">
<p>Sometimes, you do not want to create a new span but you want to continue one. An example of such a
situation might be as follows:</p>
</div>
<div class="ulist">
<ul>
<li>
<p><strong>AOP</strong>: If there was already a span created before an aspect was reached, you might not want to create a new span.</p>
</li>
<li>
<p><strong>Hystrix</strong>: Executing a Hystrix command is most likely a logical part of the current processing.
It is in fact merely a technical implementation detail that you would not necessarily want to reflect in tracing as a separate being.</p>
</li>
</ul>
</div>
<div class="paragraph">
<p>To continue a span, you can use <code>brave.Tracer</code>, as shown in the following example:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">// let's assume that we're in a thread Y and we've received
// the `initialSpan` from thread X
Span continuedSpan = this.tracer.toSpan(newSpan.context());
try {
// ...
// You can tag a span
continuedSpan.tag("taxValue", taxValue);
// ...
// You can log an event on a span
continuedSpan.annotate("taxCalculated");
}
finally {
// Once done remember to flush the span. That means that
// it will get reported but the span itself is not yet finished
continuedSpan.flush();
}</code></pre>
</div>
</div>
</div>
<div class="sect2">
<h3 id="creating-spans-with-explicit-parent"><a class="link" href="#creating-spans-with-explicit-parent">Creating a Span with an explicit Parent</a></h3>
<div class="paragraph">
<p>You might want to start a new span and provide an explicit parent of that span.
Assume that the parent of a span is in one thread and you want to start a new span in another thread.
In Brave, whenever you call <code>nextSpan()</code>, it creates a span in reference to the span that is currently in scope.
You can put the span in scope and then call <code>nextSpan()</code>, as shown in the following example:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">// let's assume that we're in a thread Y and we've received
// the `initialSpan` from thread X. `initialSpan` will be the parent
// of the `newSpan`
Span newSpan = null;
try (Tracer.SpanInScope ws = this.tracer.withSpanInScope(initialSpan)) {
newSpan = this.tracer.nextSpan().name("calculateCommission");
// ...
// You can tag a span
newSpan.tag("commissionValue", commissionValue);
// ...
// You can log an event on a span
newSpan.annotate("commissionCalculated");
}
finally {
// Once done remember to finish the span. This will allow collecting
// the span to send it to Zipkin. The tags and events set on the
// newSpan will not be present on the parent
if (newSpan != null) {
newSpan.finish();
}
}</code></pre>
</div>
</div>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
After creating such a span, you must finish it. Otherwise it is not reported (for example, to Zipkin).
</td>
</tr>
</table>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_naming_spans"><a class="link" href="#_naming_spans">Naming spans</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>Picking a span name is not a trivial task. A span name should depict an operation name.
The name should be low cardinality, so it should not include identifiers.</p>
</div>
<div class="paragraph">
<p>Since there is a lot of instrumentation going on, some span names are artificial:</p>
</div>
<div class="ulist">
<ul>
<li>
<p><code>controller-method-name</code> when received by a Controller with a method name of <code>controllerMethodName</code></p>
</li>
<li>
<p><code>async</code> for asynchronous operations done with wrapped <code>Callable</code> and <code>Runnable</code> interfaces.</p>
</li>
<li>
<p>Methods annotated with <code>@Scheduled</code> return the simple name of the class.</p>
</li>
</ul>
</div>
<div class="paragraph">
<p>Fortunately, for asynchronous processing, you can provide explicit naming.</p>
</div>
<div class="sect2">
<h3 id="_spanname_annotation"><a class="link" href="#_spanname_annotation"><code>@SpanName</code> Annotation</a></h3>
<div class="paragraph">
<p>You can name the span explicitly by using the <code>@SpanName</code> annotation, as shown in the following example:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java"> @SpanName("calculateTax")
class TaxCountingRunnable implements Runnable {
@Override
public void run() {
// perform logic
}
}
}</code></pre>
</div>
</div>
<div class="paragraph">
<p>In this case, when processed in the following manner, the span is named <code>calculateTax</code>:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">Runnable runnable = new TraceRunnable(this.tracing, spanNamer,
new TaxCountingRunnable());
Future&lt;?&gt; future = executorService.submit(runnable);
// ... some additional logic ...
future.get();</code></pre>
</div>
</div>
</div>
<div class="sect2">
<h3 id="_tostring_method"><a class="link" href="#_tostring_method"><code>toString()</code> method</a></h3>
<div class="paragraph">
<p>It is pretty rare to create separate classes for <code>Runnable</code> or <code>Callable</code>.
Typically, one creates an anonymous instance of those classes.
You cannot annotate such classes.
To overcome that limitation, if there is no <code>@SpanName</code> annotation present, we check whether the class has a custom implementation of the <code>toString()</code> method.</p>
</div>
<div class="paragraph">
<p>Running such code leads to creating a span named <code>calculateTax</code>, as shown in the following example:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">Runnable runnable = new TraceRunnable(this.tracing, spanNamer, new Runnable() {
@Override
public void run() {
// perform logic
}
@Override
public String toString() {
return "calculateTax";
}
});
Future&lt;?&gt; future = executorService.submit(runnable);
// ... some additional logic ...
future.get();</code></pre>
</div>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_managing_spans_with_annotations"><a class="link" href="#_managing_spans_with_annotations">Managing Spans with Annotations</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>You can manage spans with a variety of annotations.</p>
</div>
<div class="sect2">
<h3 id="_rationale"><a class="link" href="#_rationale">Rationale</a></h3>
<div class="paragraph">
<p>There are a number of good reasons to manage spans with annotations, including:</p>
</div>
<div class="ulist">
<ul>
<li>
<p>API-agnostic means to collaborate with a span. Use of annotations lets users add to a span with no library dependency on a span api.
Doing so lets Sleuth change its core API to create less impact to user code.</p>
</li>
<li>
<p>Reduced surface area for basic span operations. Without this feature, you must use the span api, which has lifecycle commands that could be used incorrectly.
By only exposing scope, tag, and log functionality, you can collaborate without accidentally breaking span lifecycle.</p>
</li>
<li>
<p>Collaboration with runtime generated code. With libraries such as Spring Data and Feign, the implementations of interfaces are generated at runtime.
Consequently, span wrapping of objects was tedious.
Now you can provide annotations over interfaces and the arguments of those interfaces.</p>
</li>
</ul>
</div>
</div>
<div class="sect2">
<h3 id="_creating_new_spans"><a class="link" href="#_creating_new_spans">Creating New Spans</a></h3>
<div class="paragraph">
<p>If you do not want to create local spans manually, you can use the <code>@NewSpan</code> annotation.
Also, we provide the <code>@SpanTag</code> annotation to add tags in an automated fashion.</p>
</div>
<div class="paragraph">
<p>Now we can consider some examples of usage.</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@NewSpan
void testMethod();</code></pre>
</div>
</div>
<div class="paragraph">
<p>Annotating the method without any parameter leads to creating a new span whose name equals the annotated method name.</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@NewSpan("customNameOnTestMethod4")
void testMethod4();</code></pre>
</div>
</div>
<div class="paragraph">
<p>If you provide the value in the annotation (either directly or by setting the <code>name</code> parameter), the created span has the provided value as the name.</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">// method declaration
@NewSpan(name = "customNameOnTestMethod5")
void testMethod5(@SpanTag("testTag") String param);
// and method execution
this.testBean.testMethod5("test");</code></pre>
</div>
</div>
<div class="paragraph">
<p>You can combine both the name and a tag. Let&#8217;s focus on the latter.
In this case, the value of the annotated method&#8217;s parameter runtime value becomes the value of the tag.
In our sample, the tag key is <code>testTag</code>, and the tag value is <code>test</code>.</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@NewSpan(name = "customNameOnTestMethod3")
@Override
public void testMethod3() {
}</code></pre>
</div>
</div>
<div class="paragraph">
<p>You can place the <code>@NewSpan</code> annotation on both the class and an interface.
If you override the interface&#8217;s method and provide a different value for the <code>@NewSpan</code> annotation, the most
concrete one wins (in this case <code>customNameOnTestMethod3</code> is set).</p>
</div>
</div>
<div class="sect2">
<h3 id="_continuing_spans"><a class="link" href="#_continuing_spans">Continuing Spans</a></h3>
<div class="paragraph">
<p>If you want to add tags and annotations to an existing span, you can use the <code>@ContinueSpan</code> annotation, as shown in the following example:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">// method declaration
@ContinueSpan(log = "testMethod11")
void testMethod11(@SpanTag("testTag11") String param);
// method execution
this.testBean.testMethod11("test");
this.testBean.testMethod13();</code></pre>
</div>
</div>
<div class="paragraph">
<p>(Note that, in contrast with the <code>@NewSpan</code> annotation ,you can also add logs with the <code>log</code> parameter.)</p>
</div>
<div class="paragraph">
<p>That way, the span gets continued and:</p>
</div>
<div class="ulist">
<ul>
<li>
<p>Log entries named <code>testMethod11.before</code> and <code>testMethod11.after</code> are created.</p>
</li>
<li>
<p>If an exception is thrown, a log entry named <code>testMethod11.afterFailure</code> is also created.</p>
</li>
<li>
<p>A tag with a key of <code>testTag11</code> and a value of <code>test</code> is created.</p>
</li>
</ul>
</div>
</div>
<div class="sect2">
<h3 id="_advanced_tag_setting"><a class="link" href="#_advanced_tag_setting">Advanced Tag Setting</a></h3>
<div class="paragraph">
<p>There are 3 different ways to add tags to a span. All of them are controlled by the <code>SpanTag</code> annotation.
The precedence is as follows:</p>
</div>
<div class="olist arabic">
<ol class="arabic">
<li>
<p>Try with a bean of <code>TagValueResolver</code> type and a provided name.</p>
</li>
<li>
<p>If the bean name has not been provided, try to evaluate an expression.
We search for a <code>TagValueExpressionResolver</code> bean.
The default implementation uses SPEL expression resolution.
<strong>IMPORTANT</strong> You can only reference properties from the SPEL expression. Method execution is not allowed due to security constraints.</p>
</li>
<li>
<p>If we do not find any expression to evaluate, return the <code>toString()</code> value of the parameter.</p>
</li>
</ol>
</div>
<div class="sect3">
<h4 id="_custom_extractor"><a class="link" href="#_custom_extractor">Custom extractor</a></h4>
<div class="paragraph">
<p>The value of the tag for the following method is computed by an implementation of <code>TagValueResolver</code> interface.
Its class name has to be passed as the value of the <code>resolver</code> attribute.</p>
</div>
<div class="paragraph">
<p>Consider the following annotated method:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@NewSpan
public void getAnnotationForTagValueResolver(
@SpanTag(key = "test", resolver = TagValueResolver.class) String test) {
}</code></pre>
</div>
</div>
<div class="paragraph">
<p>Now further consider the following <code>TagValueResolver</code> bean implementation:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@Bean(name = "myCustomTagValueResolver")
public TagValueResolver tagValueResolver() {
return parameter -&gt; "Value from myCustomTagValueResolver";
}</code></pre>
</div>
</div>
<div class="paragraph">
<p>The two preceding examples lead to setting a tag value equal to <code>Value from myCustomTagValueResolver</code>.</p>
</div>
</div>
<div class="sect3">
<h4 id="_resolving_expressions_for_a_value"><a class="link" href="#_resolving_expressions_for_a_value">Resolving Expressions for a Value</a></h4>
<div class="paragraph">
<p>Consider the following annotated method:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@NewSpan
public void getAnnotationForTagValueExpression(@SpanTag(key = "test",
expression = "'hello' + ' characters'") String test) {
}</code></pre>
</div>
</div>
<div class="paragraph">
<p>No custom implementation of a <code>TagValueExpressionResolver</code> leads to evaluation of the SPEL expression, and a tag with a value of <code>4 characters</code> is set on the span.
If you want to use some other expression resolution mechanism, you can create your own implementation of the bean.</p>
</div>
</div>
<div class="sect3">
<h4 id="_using_the_tostring_method"><a class="link" href="#_using_the_tostring_method">Using the <code>toString()</code> method</a></h4>
<div class="paragraph">
<p>Consider the following annotated method:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@NewSpan
public void getAnnotationForArgumentToString(@SpanTag("test") Long param) {
}</code></pre>
</div>
</div>
<div class="paragraph">
<p>Running the preceding method with a value of <code>15</code> leads to setting a tag with a String value of <code>"15"</code>.</p>
</div>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_customizations"><a class="link" href="#_customizations">Customizations</a></h2>
<div class="sectionbody">
<div class="sect2">
<h3 id="_http"><a class="link" href="#_http">HTTP</a></h3>
<div class="paragraph">
<p>If a customization of client / server parsing of the HTTP related spans is required,
just register a bean of type <code>brave.http.HttpClientParser</code> or
<code>brave.http.HttpServerParser</code>. If client /server sampling is required, just
register a bean of type <code>brave.http.HttpSampler</code> and name the bean
<code>sleuthClientSampler</code> for client sampler and <code>sleuthServerSampler</code> for server sampler.
For your convenience the <code>@ClientSampler</code> and <code>@ServerSampler</code>
annotations can be used to inject the proper beans or to
reference the bean names via their static String <code>NAME</code> fields.</p>
</div>
<div class="paragraph">
<p>Check out Brave&#8217;s code to see an example of how to make a path-based sampler
<a href="https://github.com/openzipkin/brave/tree/master/instrumentation/http#sampling-policy" class="bare">https://github.com/openzipkin/brave/tree/master/instrumentation/http#sampling-policy</a></p>
</div>
<div class="paragraph">
<p>If you want to completely rewrite the <code>HttpTracing</code> bean you can use the <code>SkipPatternProvider</code>
interface to retrieve the URL <code>Pattern</code> for spans that should be not sampled. Below you can see
an example of usage of <code>SkipPatternProvider</code> inside a server side, <code>HttpSampler</code>.</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@Configuration
class Config {
@Bean(name = ServerSampler.NAME)
HttpSampler myHttpSampler(SkipPatternProvider provider) {
Pattern pattern = provider.skipPattern();
return new HttpSampler() {
@Override
public &lt;Req&gt; Boolean trySample(HttpAdapter&lt;Req, ?&gt; adapter, Req request) {
String url = adapter.path(request);
boolean shouldSkip = pattern.matcher(url).matches();
if (shouldSkip) {
return false;
}
return null;
}
};
}
}</code></pre>
</div>
</div>
</div>
<div class="sect2">
<h3 id="_tracingfilter"><a class="link" href="#_tracingfilter"><code>TracingFilter</code></a></h3>
<div class="paragraph">
<p>You can also modify the behavior of the <code>TracingFilter</code>, which is the component that is responsible for processing the input HTTP request and adding tags basing on the HTTP response.
You can customize the tags or modify the response headers by registering your own instance of the <code>TracingFilter</code> bean.</p>
</div>
<div class="paragraph">
<p>In the following example, we register the <code>TracingFilter</code> bean, add the <code>ZIPKIN-TRACE-ID</code> response header containing the current Span&#8217;s trace id, and add a tag with key <code>custom</code> and a value <code>tag</code> to the span.</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@Component
@Order(TraceWebServletAutoConfiguration.TRACING_FILTER_ORDER + 1)
class MyFilter extends GenericFilterBean {
private final Tracer tracer;
MyFilter(Tracer tracer) {
this.tracer = tracer;
}
@Override
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
Span currentSpan = this.tracer.currentSpan();
if (currentSpan == null) {
chain.doFilter(request, response);
return;
}
// for readability we're returning trace id in a hex form
((HttpServletResponse) response).addHeader("ZIPKIN-TRACE-ID",
currentSpan.context().traceIdString());
// we can also add some custom tags
currentSpan.tag("custom", "tag");
chain.doFilter(request, response);
}
}</code></pre>
</div>
</div>
</div>
<div class="sect2">
<h3 id="_custom_service_name"><a class="link" href="#_custom_service_name">Custom service name</a></h3>
<div class="paragraph">
<p>By default, Sleuth assumes that, when you send a span to Zipkin, you want the span&#8217;s service name to be equal to the value of the <code>spring.application.name</code> property.
That is not always the case, though.
There are situations in which you want to explicitly provide a different service name for all spans coming from your application.
To achieve that, you can pass the following property to your application to override that value (the example is for a service named <code>myService</code>):</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-yaml hljs" data-lang="yaml">spring.zipkin.service.name: myService</code></pre>
</div>
</div>
</div>
<div class="sect2">
<h3 id="_customization_of_reported_spans"><a class="link" href="#_customization_of_reported_spans">Customization of Reported Spans</a></h3>
<div class="paragraph">
<p>Before reporting spans (for example, to Zipkin) you may want to modify that span in some way.
You can do so by using the <code>FinishedSpanHandler</code> interface.</p>
</div>
<div class="paragraph">
<p>In Sleuth, we generate spans with a fixed name.
Some users want to modify the name depending on values of tags.
You can implement the <code>FinishedSpanHandler</code> interface to alter that name.</p>
</div>
<div class="paragraph">
<p>The following example shows how to register two beans that implement <code>FinishedSpanHandler</code>:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@Bean
FinishedSpanHandler handlerOne() {
return new FinishedSpanHandler() {
@Override
public boolean handle(TraceContext traceContext, MutableSpan span) {
span.name("foo");
return true; // keep this span
}
};
}
@Bean
FinishedSpanHandler handlerTwo() {
return new FinishedSpanHandler() {
@Override
public boolean handle(TraceContext traceContext, MutableSpan span) {
span.name(span.name() + " bar");
return true; // keep this span
}
};
}</code></pre>
</div>
</div>
<div class="paragraph">
<p>The preceding example results in changing the name of the reported span to <code>foo bar</code>, just before it gets reported (for example, to Zipkin).</p>
</div>
</div>
<div class="sect2">
<h3 id="_host_locator"><a class="link" href="#_host_locator">Host Locator</a></h3>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
This section is about defining <strong>host</strong> from service discovery.
It is <strong>NOT</strong> about finding Zipkin through service discovery.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>To define the host that corresponds to a particular span, we need to resolve the host name and port.
The default approach is to take these values from server properties.
If those are not set, we try to retrieve the host name from the network interfaces.</p>
</div>
<div class="paragraph">
<p>If you have the discovery client enabled and prefer to retrieve the host address from the registered instance in a service registry, you have to set the <code>spring.zipkin.locator.discovery.enabled</code> property (it is applicable for both HTTP-based and Stream-based span reporting), as follows:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-yaml hljs" data-lang="yaml">spring.zipkin.locator.discovery.enabled: true</code></pre>
</div>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_sending_spans_to_zipkin"><a class="link" href="#_sending_spans_to_zipkin">Sending Spans to Zipkin</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>By default, if you add <code>spring-cloud-starter-zipkin</code> as a dependency to your project, when the span is closed, it is sent to Zipkin over HTTP.
The communication is asynchronous.
You can configure the URL by setting the <code>spring.zipkin.baseUrl</code> property, as follows:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-yaml hljs" data-lang="yaml">spring.zipkin.baseUrl: https://192.168.99.100:9411/</code></pre>
</div>
</div>
<div class="paragraph">
<p>If you want to find Zipkin through service discovery, you can pass the Zipkin&#8217;s service ID inside the URL, as shown in the following example for <code>zipkinserver</code> service ID:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-yaml hljs" data-lang="yaml">spring.zipkin.baseUrl: https://zipkinserver/</code></pre>
</div>
</div>
<div class="paragraph">
<p>To disable this feature just set <code>spring.zipkin.discoveryClientEnabled</code> to `false.</p>
</div>
<div class="paragraph">
<p>When the Discovery Client feature is enabled, Sleuth uses
<code>LoadBalancerClient</code> to find the URL of the Zipkin Server. It means
that you can set up the load balancing configuration e.g. via Ribbon.</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-yaml hljs" data-lang="yaml">zipkinserver:
ribbon:
ListOfServers: host1,host2</code></pre>
</div>
</div>
<div class="paragraph">
<p>If you have web, rabbit, or kafka together on the classpath, you might need to pick the means by which you would like to send spans to zipkin.
To do so, set <code>web</code>, <code>rabbit</code>, or <code>kafka</code> to the <code>spring.zipkin.sender.type</code> property.
The following example shows setting the sender type for <code>web</code>:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-yaml hljs" data-lang="yaml">spring.zipkin.sender.type: web</code></pre>
</div>
</div>
<div class="paragraph">
<p>To customize the <code>RestTemplate</code> that sends spans to Zipkin via HTTP, you can register
the <code>ZipkinRestTemplateCustomizer</code> bean.</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@Configuration
class MyConfig {
@Bean ZipkinRestTemplateCustomizer myCustomizer() {
return new ZipkinRestTemplateCustomizer() {
@Override
void customize(RestTemplate restTemplate) {
// customize the RestTemplate
}
};
}
}</code></pre>
</div>
</div>
<div class="paragraph">
<p>If, however, you would like to control the full process of creating the <code>RestTemplate</code>
object, you will have to create a bean of <code>zipkin2.reporter.Sender</code> type.</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java"> @Bean Sender myRestTemplateSender(ZipkinProperties zipkin,
ZipkinRestTemplateCustomizer zipkinRestTemplateCustomizer) {
RestTemplate restTemplate = mySuperCustomRestTemplate();
zipkinRestTemplateCustomizer.customize(restTemplate);
return myCustomSender(zipkin, restTemplate);
}</code></pre>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_zipkin_stream_span_consumer"><a class="link" href="#_zipkin_stream_span_consumer">Zipkin Stream Span Consumer</a></h2>
<div class="sectionbody">
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
We recommend using Zipkin&#8217;s native support for message-based span sending.
Starting from the Edgware release, the Zipkin Stream server is deprecated.
In the Finchley release, it got removed.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>If for some reason you need to create the deprecated Stream Zipkin server, see the <a href="https://cloud.spring.io/spring-cloud-static/Dalston.SR4/multi/multi__span_data_as_messages.html#_zipkin_consumer">Dalston Documentation</a>.</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_integrations"><a class="link" href="#_integrations">Integrations</a></h2>
<div class="sectionbody">
<div class="sect2">
<h3 id="_opentracing"><a class="link" href="#_opentracing">OpenTracing</a></h3>
<div class="paragraph">
<p>Spring Cloud Sleuth is compatible with <a href="https://opentracing.io/">OpenTracing</a>.
If you have OpenTracing on the classpath, we automatically register the OpenTracing <code>Tracer</code> bean.
If you wish to disable this, set <code>spring.sleuth.opentracing.enabled</code> to <code>false</code></p>
</div>
</div>
<div class="sect2">
<h3 id="_runnable_and_callable"><a class="link" href="#_runnable_and_callable">Runnable and Callable</a></h3>
<div class="paragraph">
<p>If you wrap your logic in <code>Runnable</code> or <code>Callable</code>, you can wrap those classes in their Sleuth representative, as shown in the following example for <code>Runnable</code>:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">Runnable runnable = new Runnable() {
@Override
public void run() {
// do some work
}
@Override
public String toString() {
return "spanNameFromToStringMethod";
}
};
// Manual `TraceRunnable` creation with explicit "calculateTax" Span name
Runnable traceRunnable = new TraceRunnable(this.tracing, spanNamer, runnable,
"calculateTax");
// Wrapping `Runnable` with `Tracing`. That way the current span will be available
// in the thread of `Runnable`
Runnable traceRunnableFromTracer = this.tracing.currentTraceContext()
.wrap(runnable);</code></pre>
</div>
</div>
<div class="paragraph">
<p>The following example shows how to do so for <code>Callable</code>:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">Callable&lt;String&gt; callable = new Callable&lt;String&gt;() {
@Override
public String call() throws Exception {
return someLogic();
}
@Override
public String toString() {
return "spanNameFromToStringMethod";
}
};
// Manual `TraceCallable` creation with explicit "calculateTax" Span name
Callable&lt;String&gt; traceCallable = new TraceCallable&lt;&gt;(this.tracing, spanNamer,
callable, "calculateTax");
// Wrapping `Callable` with `Tracing`. That way the current span will be available
// in the thread of `Callable`
Callable&lt;String&gt; traceCallableFromTracer = this.tracing.currentTraceContext()
.wrap(callable);</code></pre>
</div>
</div>
<div class="paragraph">
<p>That way, you ensure that a new span is created and closed for each execution.</p>
</div>
</div>
<div class="sect2">
<h3 id="_hystrix"><a class="link" href="#_hystrix">Hystrix</a></h3>
<div class="sect3">
<h4 id="_custom_concurrency_strategy"><a class="link" href="#_custom_concurrency_strategy">Custom Concurrency Strategy</a></h4>
<div class="paragraph">
<p>We register a custom <a href="https://github.com/Netflix/Hystrix/wiki/Plugins#concurrencystrategy"><code>HystrixConcurrencyStrategy</code></a> called <code>TraceCallable</code> that wraps all <code>Callable</code> instances in their Sleuth representative.
The strategy either starts or continues a span, depending on whether tracing was already going on before the Hystrix command was called.
To disable the custom Hystrix Concurrency Strategy, set the <code>spring.sleuth.hystrix.strategy.enabled</code> to <code>false</code>.</p>
</div>
</div>
<div class="sect3">
<h4 id="_manual_command_setting"><a class="link" href="#_manual_command_setting">Manual Command setting</a></h4>
<div class="paragraph">
<p>Assume that you have the following <code>HystrixCommand</code>:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">HystrixCommand&lt;String&gt; hystrixCommand = new HystrixCommand&lt;String&gt;(setter) {
@Override
protected String run() throws Exception {
return someLogic();
}
};</code></pre>
</div>
</div>
<div class="paragraph">
<p>To pass the tracing information, you have to wrap the same logic in the Sleuth version of the <code>HystrixCommand</code>, which is called
<code>TraceCommand</code>, as shown in the following example:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">TraceCommand&lt;String&gt; traceCommand = new TraceCommand&lt;String&gt;(tracer, setter) {
@Override
public String doRun() throws Exception {
return someLogic();
}
};</code></pre>
</div>
</div>
</div>
</div>
<div class="sect2">
<h3 id="_rxjava"><a class="link" href="#_rxjava">RxJava</a></h3>
<div class="paragraph">
<p>We registering a custom <a href="https://github.com/ReactiveX/RxJava/wiki/Plugins#rxjavaschedulershook"><code>RxJavaSchedulersHook</code></a> that wraps all <code>Action0</code> instances in their Sleuth representative, which is called <code>TraceAction</code>.
The hook either starts or continues a span, depending on whether tracing was already going on before the Action was scheduled.
To disable the custom <code>RxJavaSchedulersHook</code>, set the <code>spring.sleuth.rxjava.schedulers.hook.enabled</code> to <code>false</code>.</p>
</div>
<div class="paragraph">
<p>You can define a list of regular expressions for thread names for which you do not want spans to be created.
To do so, provide a comma-separated list of regular expressions in the <code>spring.sleuth.rxjava.schedulers.ignoredthreads</code> property.</p>
</div>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
The suggest approach to reactive programming and Sleuth is to use
the Reactor support.
</td>
</tr>
</table>
</div>
</div>
<div class="sect2">
<h3 id="_http_integration"><a class="link" href="#_http_integration">HTTP integration</a></h3>
<div class="paragraph">
<p>Features from this section can be disabled by setting the <code>spring.sleuth.web.enabled</code> property with value equal to <code>false</code>.</p>
</div>
<div class="sect3">
<h4 id="_http_filter"><a class="link" href="#_http_filter">HTTP Filter</a></h4>
<div class="paragraph">
<p>Through the <code>TracingFilter</code>, all sampled incoming requests result in creation of a Span.
That Span&#8217;s name is <code>http:</code> + the path to which the request was sent.
For example, if the request was sent to <code>/this/that</code> then the name will be <code>http:/this/that</code>.
You can configure which URIs you would like to skip by setting the <code>spring.sleuth.web.skipPattern</code> property.
If you have <code>ManagementServerProperties</code> on classpath, its value of <code>contextPath</code> gets appended to the provided skip pattern.
If you want to reuse the Sleuth&#8217;s default skip patterns and just append your own, pass those patterns by using the <code>spring.sleuth.web.additionalSkipPattern</code>.</p>
</div>
<div class="paragraph">
<p>By default, all the spring boot actuator endpoints are automatically added to the skip pattern.
If you want to disable this behaviour set <code>spring.sleuth.web.ignore-auto-configured-skip-patterns</code>
to <code>true</code>.</p>
</div>
<div class="paragraph">
<p>To change the order of tracing filter registration, please set the
<code>spring.sleuth.web.filter-order</code> property.</p>
</div>
<div class="paragraph">
<p>To disable the filter that logs uncaught exceptions you can disable the
<code>spring.sleuth.web.exception-throwing-filter-enabled</code> property.</p>
</div>
</div>
<div class="sect3">
<h4 id="_handlerinterceptor"><a class="link" href="#_handlerinterceptor">HandlerInterceptor</a></h4>
<div class="paragraph">
<p>Since we want the span names to be precise, we use a <code>TraceHandlerInterceptor</code> that either wraps an existing <code>HandlerInterceptor</code> or is added directly to the list of existing <code>HandlerInterceptors</code>.
The <code>TraceHandlerInterceptor</code> adds a special request attribute to the given <code>HttpServletRequest</code>.
If the the <code>TracingFilter</code> does not see this attribute, it creates a "<code>fallback</code>" span, which is an additional span created on the server side so that the trace is presented properly in the UI.
If that happens, there is probably missing instrumentation.
In that case, please file an issue in Spring Cloud Sleuth.</p>
</div>
</div>
<div class="sect3">
<h4 id="_async_servlet_support"><a class="link" href="#_async_servlet_support">Async Servlet support</a></h4>
<div class="paragraph">
<p>If your controller returns a <code>Callable</code> or a <code>WebAsyncTask</code>, Spring Cloud Sleuth continues the existing span instead of creating a new one.</p>
</div>
</div>
<div class="sect3">
<h4 id="_webflux_support"><a class="link" href="#_webflux_support">WebFlux support</a></h4>
<div class="paragraph">
<p>Through <code>TraceWebFilter</code>, all sampled incoming requests result in creation of a Span.
That Span&#8217;s name is <code>http:</code> + the path to which the request was sent.
For example, if the request was sent to <code>/this/that</code>, the name is <code>http:/this/that</code>.
You can configure which URIs you would like to skip by using the <code>spring.sleuth.web.skipPattern</code> property.
If you have <code>ManagementServerProperties</code> on the classpath, its value of <code>contextPath</code> gets appended to the provided skip pattern.
If you want to reuse Sleuth&#8217;s default skip patterns and append your own, pass those patterns by using the <code>spring.sleuth.web.additionalSkipPattern</code>.</p>
</div>
<div class="paragraph">
<p>To change the order of tracing filter registration, please set the
<code>spring.sleuth.web.filter-order</code> property.</p>
</div>
</div>
<div class="sect3">
<h4 id="_dubbo_rpc_support"><a class="link" href="#_dubbo_rpc_support">Dubbo RPC support</a></h4>
<div class="paragraph">
<p>Via the integration with Brave, Spring Cloud Sleuth supports <a href="https://dubbo.apache.org/">Dubbo</a>.
It&#8217;s enough to add the <code>brave-instrumentation-dubbo-rpc</code> dependency:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-xml hljs" data-lang="xml">&lt;dependency&gt;
&lt;groupId&gt;io.zipkin.brave&lt;/groupId&gt;
&lt;artifactId&gt;brave-instrumentation-dubbo-rpc&lt;/artifactId&gt;
&lt;/dependency&gt;</code></pre>
</div>
</div>
<div class="paragraph">
<p>You need to also set a <code>dubbo.properties</code> file with the following contents:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-properties hljs" data-lang="properties">dubbo.provider.filter=tracing
dubbo.consumer.filter=tracing</code></pre>
</div>
</div>
<div class="paragraph">
<p>You can read more about Brave - Dubbo integration <a href="https://github.com/openzipkin/brave/tree/master/instrumentation/dubbo-rpc">here</a>.
An example of Spring Cloud Sleuth and Dubbo can be found <a href="https://github.com/openzipkin/sleuth-webmvc-example/compare/add-dubbo-tracing">here</a>.</p>
</div>
</div>
</div>
<div class="sect2">
<h3 id="_http_client_integration"><a class="link" href="#_http_client_integration">HTTP Client Integration</a></h3>
<div class="sect3">
<h4 id="_synchronous_rest_template"><a class="link" href="#_synchronous_rest_template">Synchronous Rest Template</a></h4>
<div class="paragraph">
<p>We inject a <code>RestTemplate</code> interceptor to ensure that all the tracing information is passed to the requests.
Each time a call is made, a new Span is created.
It gets closed upon receiving the response.
To block the synchronous <code>RestTemplate</code> features, set <code>spring.sleuth.web.client.enabled</code> to <code>false</code>.</p>
</div>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
You have to register <code>RestTemplate</code> as a bean so that the interceptors get injected.
If you create a <code>RestTemplate</code> instance with a <code>new</code> keyword, the instrumentation does NOT work.
</td>
</tr>
</table>
</div>
</div>
<div class="sect3">
<h4 id="_asynchronous_rest_template"><a class="link" href="#_asynchronous_rest_template">Asynchronous Rest Template</a></h4>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
Starting with Sleuth <code>2.0.0</code>, we no longer register a bean of <code>AsyncRestTemplate</code> type.
It is up to you to create such a bean.
Then we instrument it.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>To block the <code>AsyncRestTemplate</code> features, set <code>spring.sleuth.web.async.client.enabled</code> to <code>false</code>.
To disable creation of the default <code>TraceAsyncClientHttpRequestFactoryWrapper</code>, set <code>spring.sleuth.web.async.client.factory.enabled</code>
to <code>false</code>.
If you do not want to create <code>AsyncRestClient</code> at all, set <code>spring.sleuth.web.async.client.template.enabled</code> to <code>false</code>.</p>
</div>
<div class="sect4">
<h5 id="_multiple_asynchronous_rest_templates"><a class="link" href="#_multiple_asynchronous_rest_templates">Multiple Asynchronous Rest Templates</a></h5>
<div class="paragraph">
<p>Sometimes you need to use multiple implementations of the Asynchronous Rest Template.
In the following snippet, you can see an example of how to set up such a custom <code>AsyncRestTemplate</code>:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@Configuration
@EnableAutoConfiguration
static class Config {
@Bean(name = "customAsyncRestTemplate")
public AsyncRestTemplate traceAsyncRestTemplate() {
return new AsyncRestTemplate(asyncClientFactory(),
clientHttpRequestFactory());
}
private ClientHttpRequestFactory clientHttpRequestFactory() {
ClientHttpRequestFactory clientHttpRequestFactory = new CustomClientHttpRequestFactory();
// CUSTOMIZE HERE
return clientHttpRequestFactory;
}
private AsyncClientHttpRequestFactory asyncClientFactory() {
AsyncClientHttpRequestFactory factory = new CustomAsyncClientHttpRequestFactory();
// CUSTOMIZE HERE
return factory;
}
}</code></pre>
</div>
</div>
</div>
</div>
<div class="sect3">
<h4 id="_webclient"><a class="link" href="#_webclient"><code>WebClient</code></a></h4>
<div class="paragraph">
<p>We inject a <code>ExchangeFilterFunction</code> implementation that creates a span and, through on-success and on-error callbacks, takes care of closing client-side spans.</p>
</div>
<div class="paragraph">
<p>To block this feature, set <code>spring.sleuth.web.client.enabled</code> to <code>false</code>.</p>
</div>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
You have to register <code>WebClient</code> as a bean so that the tracing instrumentation gets applied.
If you create a <code>WebClient</code> instance with a <code>new</code> keyword, the instrumentation does NOT work.
</td>
</tr>
</table>
</div>
</div>
<div class="sect3">
<h4 id="_traverson"><a class="link" href="#_traverson">Traverson</a></h4>
<div class="paragraph">
<p>If you use the <a href="https://docs.spring.io/spring-hateoas/docs/current/reference/html/#client.traverson">Traverson</a> library, you can inject a <code>RestTemplate</code> as a bean into your Traverson object.
Since <code>RestTemplate</code> is already intercepted, you get full support for tracing in your client. The following pseudo code
shows how to do that:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@Autowired RestTemplate restTemplate;
Traverson traverson = new Traverson(URI.create("https://some/address"),
MediaType.APPLICATION_JSON, MediaType.APPLICATION_JSON_UTF8).setRestOperations(restTemplate);
// use Traverson</code></pre>
</div>
</div>
</div>
<div class="sect3">
<h4 id="_apache_httpclientbuilder_and_httpasyncclientbuilder"><a class="link" href="#_apache_httpclientbuilder_and_httpasyncclientbuilder">Apache <code>HttpClientBuilder</code> and <code>HttpAsyncClientBuilder</code></a></h4>
<div class="paragraph">
<p>We instrument the <code>HttpClientBuilder</code> and <code>HttpAsyncClientBuilder</code> so that
tracing context gets injected to the sent requests.</p>
</div>
<div class="paragraph">
<p>To block these features, set <code>spring.sleuth.web.client.enabled</code> to <code>false</code>.</p>
</div>
</div>
<div class="sect3">
<h4 id="_netty_httpclient"><a class="link" href="#_netty_httpclient">Netty <code>HttpClient</code></a></h4>
<div class="paragraph">
<p>We instrument the Netty&#8217;s <code>HttpClient</code>.</p>
</div>
<div class="paragraph">
<p>To block this feature, set <code>spring.sleuth.web.client.enabled</code> to <code>false</code>.</p>
</div>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
You have to register <code>HttpClient</code> as a bean so that the instrumentation happens.
If you create a <code>HttpClient</code> instance with a <code>new</code> keyword, the instrumentation does NOT work.
</td>
</tr>
</table>
</div>
</div>
<div class="sect3">
<h4 id="_userinforesttemplatecustomizer"><a class="link" href="#_userinforesttemplatecustomizer"><code>UserInfoRestTemplateCustomizer</code></a></h4>
<div class="paragraph">
<p>We instrument the Spring Security&#8217;s <code>UserInfoRestTemplateCustomizer</code>.</p>
</div>
<div class="paragraph">
<p>To block this feature, set <code>spring.sleuth.web.client.enabled</code> to <code>false</code>.</p>
</div>
</div>
</div>
<div class="sect2">
<h3 id="_feign"><a class="link" href="#_feign">Feign</a></h3>
<div class="paragraph">
<p>By default, Spring Cloud Sleuth provides integration with Feign through <code>TraceFeignClientAutoConfiguration</code>.
You can disable it entirely by setting <code>spring.sleuth.feign.enabled</code> to <code>false</code>.
If you do so, no Feign-related instrumentation take place.</p>
</div>
<div class="paragraph">
<p>Part of Feign instrumentation is done through a <code>FeignBeanPostProcessor</code>.
You can disable it by setting <code>spring.sleuth.feign.processor.enabled</code> to <code>false</code>.
If you set it to <code>false</code>, Spring Cloud Sleuth does not instrument any of your custom Feign components.
However, all the default instrumentation is still there.</p>
</div>
</div>
<div class="sect2">
<h3 id="_grpc"><a class="link" href="#_grpc">gRPC</a></h3>
<div class="paragraph">
<p>Spring Cloud Sleuth provides instrumentation for <a href="https://grpc.io/">gRPC</a> through <code>TraceGrpcAutoConfiguration</code>. You can disable it entirely by setting <code>spring.sleuth.grpc.enabled</code> to <code>false</code>.</p>
</div>
<div class="sect3">
<h4 id="_variant_1"><a class="link" href="#_variant_1">Variant 1</a></h4>
<div class="sect4">
<h5 id="_dependencies"><a class="link" href="#_dependencies">Dependencies</a></h5>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
The gRPC integration relies on two external libraries to instrument clients and servers and both of those libraries must be on the class path to enable the instrumentation.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>Maven:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code> &lt;dependency&gt;
&lt;groupId&gt;io.github.lognet&lt;/groupId&gt;
&lt;artifactId&gt;grpc-spring-boot-starter&lt;/artifactId&gt;
&lt;/dependency&gt;
&lt;dependency&gt;
&lt;groupId&gt;io.zipkin.brave&lt;/groupId&gt;
&lt;artifactId&gt;brave-instrumentation-grpc&lt;/artifactId&gt;
&lt;/dependency&gt;</code></pre>
</div>
</div>
<div class="paragraph">
<p>Gradle:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code> compile("io.github.lognet:grpc-spring-boot-starter")
compile("io.zipkin.brave:brave-instrumentation-grpc")</code></pre>
</div>
</div>
</div>
<div class="sect4">
<h5 id="_server_instrumentation"><a class="link" href="#_server_instrumentation">Server Instrumentation</a></h5>
<div class="paragraph">
<p>Spring Cloud Sleuth leverages grpc-spring-boot-starter to register Brave&#8217;s gRPC server interceptor with all services annotated with <code>@GRpcService</code>.</p>
</div>
</div>
<div class="sect4">
<h5 id="_client_instrumentation"><a class="link" href="#_client_instrumentation">Client Instrumentation</a></h5>
<div class="paragraph">
<p>gRPC clients leverage a <code>ManagedChannelBuilder</code> to construct a <code>ManagedChannel</code> used to communicate to the gRPC server. The native <code>ManagedChannelBuilder</code> provides static methods as entry points for construction of <code>ManagedChannel</code> instances, however, this mechanism is outside the influence of the Spring application context.</p>
</div>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
Spring Cloud Sleuth provides a <code>SpringAwareManagedChannelBuilder</code> that can be customized through the Spring application context and injected by gRPC clients. <strong>This builder must be used when creating <code>ManagedChannel</code> instances.</strong>
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>Sleuth creates a <code>TracingManagedChannelBuilderCustomizer</code> which inject Brave&#8217;s client interceptor into the <code>SpringAwareManagedChannelBuilder</code>.</p>
</div>
</div>
</div>
<div class="sect3">
<h4 id="_variant_2"><a class="link" href="#_variant_2">Variant 2</a></h4>
<div class="paragraph">
<p><a href="https://github.com/yidongnan/grpc-spring-boot-starter">Grpc Spring Boot Starter</a> automatically detects the presence of Spring Cloud Sleuth and brave&#8217;s instrumentation for gRPC and registers the necessary client and/or server tooling.</p>
</div>
</div>
</div>
<div class="sect2">
<h3 id="_asynchronous_communication"><a class="link" href="#_asynchronous_communication">Asynchronous Communication</a></h3>
<div class="sect3">
<h4 id="_async_annotated_methods"><a class="link" href="#_async_annotated_methods"><code>@Async</code> Annotated methods</a></h4>
<div class="paragraph">
<p>In Spring Cloud Sleuth, we instrument async-related components so that the tracing information is passed between threads.
You can disable this behavior by setting the value of <code>spring.sleuth.async.enabled</code> to <code>false</code>.</p>
</div>
<div class="paragraph">
<p>If you annotate your method with <code>@Async</code>, we automatically create a new Span with the following characteristics:</p>
</div>
<div class="ulist">
<ul>
<li>
<p>If the method is annotated with <code>@SpanName</code>, the value of the annotation is the Span&#8217;s name.</p>
</li>
<li>
<p>If the method is not annotated with <code>@SpanName</code>, the Span name is the annotated method name.</p>
</li>
<li>
<p>The span is tagged with the method&#8217;s class name and method name.</p>
</li>
</ul>
</div>
</div>
<div class="sect3">
<h4 id="_scheduled_annotated_methods"><a class="link" href="#_scheduled_annotated_methods"><code>@Scheduled</code> Annotated Methods</a></h4>
<div class="paragraph">
<p>In Spring Cloud Sleuth, we instrument scheduled method execution so that the tracing information is passed between threads.
You can disable this behavior by setting the value of <code>spring.sleuth.scheduled.enabled</code> to <code>false</code>.</p>
</div>
<div class="paragraph">
<p>If you annotate your method with <code>@Scheduled</code>, we automatically create a new span with the following characteristics:</p>
</div>
<div class="ulist">
<ul>
<li>
<p>The span name is the annotated method name.</p>
</li>
<li>
<p>The span is tagged with the method&#8217;s class name and method name.</p>
</li>
</ul>
</div>
<div class="paragraph">
<p>If you want to skip span creation for some <code>@Scheduled</code> annotated classes, you can set the <code>spring.sleuth.scheduled.skipPattern</code> with a regular expression that matches the fully qualified name of the <code>@Scheduled</code> annotated class.
If you use <code>spring-cloud-sleuth-stream</code> and <code>spring-cloud-netflix-hystrix-stream</code> together, a span is created for each Hystrix metrics and sent to Zipkin.
This behavior may be annoying. That&#8217;s why, by default, <code>spring.sleuth.scheduled.skipPattern=org.springframework.cloud.netflix.hystrix.stream.HystrixStreamTask</code>.</p>
</div>
</div>
<div class="sect3">
<h4 id="_executor_executorservice_and_scheduledexecutorservice"><a class="link" href="#_executor_executorservice_and_scheduledexecutorservice">Executor, ExecutorService, and ScheduledExecutorService</a></h4>
<div class="paragraph">
<p>We provide <code>LazyTraceExecutor</code>, <code>TraceableExecutorService</code>, and <code>TraceableScheduledExecutorService</code>. Those implementations create spans each time a new task is submitted, invoked, or scheduled.</p>
</div>
<div class="paragraph">
<p>The following example shows how to pass tracing information with <code>TraceableExecutorService</code> when working with <code>CompletableFuture</code>:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">CompletableFuture&lt;Long&gt; completableFuture = CompletableFuture.supplyAsync(() -&gt; {
// perform some logic
return 1_000_000L;
}, new TraceableExecutorService(beanFactory, executorService,
// 'calculateTax' explicitly names the span - this param is optional
"calculateTax"));</code></pre>
</div>
</div>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
Sleuth does not work with <code>parallelStream()</code> out of the box.
If you want to have the tracing information propagated through the stream, you have to use the approach with <code>supplyAsync(...)</code>, as shown earlier.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>If there are beans that implement the <code>Executor</code> interface that you would like
to exclude from span creation, you can use the <code>spring.sleuth.async.ignored-beans</code>
property where you can provide a list of bean names.</p>
</div>
<div class="sect4">
<h5 id="_customization_of_executors"><a class="link" href="#_customization_of_executors">Customization of Executors</a></h5>
<div class="paragraph">
<p>Sometimes, you need to set up a custom instance of the <code>AsyncExecutor</code>.
The following example shows how to set up such a custom <code>Executor</code>:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@Configuration
@EnableAutoConfiguration
@EnableAsync
// add the infrastructure role to ensure that the bean gets auto-proxied
@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
static class CustomExecutorConfig extends AsyncConfigurerSupport {
@Autowired
BeanFactory beanFactory;
@Override
public Executor getAsyncExecutor() {
ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
// CUSTOMIZE HERE
executor.setCorePoolSize(7);
executor.setMaxPoolSize(42);
executor.setQueueCapacity(11);
executor.setThreadNamePrefix("MyExecutor-");
// DON'T FORGET TO INITIALIZE
executor.initialize();
return new LazyTraceExecutor(this.beanFactory, executor);
}
}</code></pre>
</div>
</div>
<div class="admonitionblock tip">
<table>
<tr>
<td class="icon">
<i class="fa icon-tip" title="Tip"></i>
</td>
<td class="content">
To ensure that your configuration gets post processed, remember
to add the <code>@Role(BeanDefinition.ROLE_INFRASTRUCTURE)</code> on your
<code>@Configuration</code> class
</td>
</tr>
</table>
</div>
</div>
</div>
</div>
<div class="sect2">
<h3 id="_messaging"><a class="link" href="#_messaging">Messaging</a></h3>
<div class="paragraph">
<p>Features from this section can be disabled by setting the <code>spring.sleuth.messaging.enabled</code> property with value equal to <code>false</code>.</p>
</div>
<div class="sect3">
<h4 id="_spring_integration_and_spring_cloud_stream"><a class="link" href="#_spring_integration_and_spring_cloud_stream">Spring Integration and Spring Cloud Stream</a></h4>
<div class="paragraph">
<p>Spring Cloud Sleuth integrates with <a href="https://projects.spring.io/spring-integration/">Spring Integration</a>.
It creates spans for publish and subscribe events.
To disable Spring Integration instrumentation, set <code>spring.sleuth.integration.enabled</code> to <code>false</code>.</p>
</div>
<div class="paragraph">
<p>You can provide the <code>spring.sleuth.integration.patterns</code> pattern to explicitly provide the names of channels that you want to include for tracing.
By default, all channels but <code>hystrixStreamOutput</code> channel are included.</p>
</div>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
When using the <code>Executor</code> to build a Spring Integration <code>IntegrationFlow</code>, you must use the untraced version of the <code>Executor</code>.
Decorating the Spring Integration Executor Channel with <code>TraceableExecutorService</code> causes the spans to be improperly closed.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>If you want to customize the way tracing context is read from and written to message headers,
it&#8217;s enough for you to register beans of types:</p>
</div>
<div class="ulist">
<ul>
<li>
<p><code>Propagation.Setter&lt;MessageHeaderAccessor, String&gt;</code> - for writing headers to the message</p>
</li>
<li>
<p><code>Propagation.Getter&lt;MessageHeaderAccessor, String&gt;</code> - for reading headers from the message</p>
</li>
</ul>
</div>
</div>
<div class="sect3">
<h4 id="_spring_rabbitmq"><a class="link" href="#_spring_rabbitmq">Spring RabbitMq</a></h4>
<div class="paragraph">
<p>We instrument the <code>RabbitTemplate</code> so that tracing headers get injected
into the message.</p>
</div>
<div class="paragraph">
<p>To block this feature, set <code>spring.sleuth.messaging.rabbit.enabled</code> to <code>false</code>.</p>
</div>
</div>
<div class="sect3">
<h4 id="_spring_kafka"><a class="link" href="#_spring_kafka">Spring Kafka</a></h4>
<div class="paragraph">
<p>We instrument the Spring Kafka&#8217;s <code>ProducerFactory</code> and <code>ConsumerFactory</code>
so that tracing headers get injected into the created Spring Kafka&#8217;s
<code>Producer</code> and <code>Consumer</code>.</p>
</div>
<div class="paragraph">
<p>To block this feature, set <code>spring.sleuth.messaging.kafka.enabled</code> to <code>false</code>.</p>
</div>
</div>
<div class="sect3">
<h4 id="_spring_kafka_streams"><a class="link" href="#_spring_kafka_streams">Spring Kafka Streams</a></h4>
<div class="paragraph">
<p>We instrument the <code>KafkaStreams</code> <code>KafkaClientSupplier</code> so that tracing headers
get injected into the <code>Producer</code> and <code>Consumer`s. A `KafkaStreamsTracing</code> bean
allows for further instrumentation through additional <code>TransformerSupplier</code> and
<code>ProcessorSupplier</code> methods.</p>
</div>
<div class="paragraph">
<p>To block this feature, set <code>spring.sleuth.messaging.kafka.streams.enabled</code> to <code>false</code>.</p>
</div>
</div>
<div class="sect3">
<h4 id="_spring_jms"><a class="link" href="#_spring_jms">Spring JMS</a></h4>
<div class="paragraph">
<p>We instrument the <code>JmsTemplate</code> so that tracing headers get injected
into the message. We also support <code>@JmsListener</code> annotated methods on the consumer side.</p>
</div>
<div class="paragraph">
<p>To block this feature, set <code>spring.sleuth.messaging.jms.enabled</code> to <code>false</code>.</p>
</div>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
We don&#8217;t support baggage propagation for JMS
</td>
</tr>
</table>
</div>
</div>
</div>
<div class="sect2">
<h3 id="_zuul"><a class="link" href="#_zuul">Zuul</a></h3>
<div class="paragraph">
<p>We instrument the Zuul Ribbon integration by enriching the Ribbon requests with tracing information.
To disable Zuul support, set the <code>spring.sleuth.zuul.enabled</code> property to <code>false</code>.</p>
</div>
</div>
<div class="sect2">
<h3 id="_redis"><a class="link" href="#_redis">Redis</a></h3>
<div class="paragraph">
<p>We set <code>tracing</code> property to Lettcue <code>ClientResources</code> instance to enable Brave tracing built in Lettuce .
To disable Redis support, set the <code>spring.sleuth.redis.enabled</code> property to <code>false</code>.</p>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_running_examples"><a class="link" href="#_running_examples">Running examples</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>You can see the running examples deployed in the <a href="https://run.pivotal.io/">Pivotal Web Services</a>.
Check them out at the following links:</p>
</div>
<div class="ulist">
<ul>
<li>
<p><a href="https://docssleuth-zipkin-server.cfapps.io/">Zipkin for apps presented in the samples to the top</a>. First make
a request to <a href="https://docssleuth-service1.cfapps.io/start">Service 1</a> and then check out the trace in Zipkin.</p>
</li>
<li>
<p><a href="https://docsbrewing-zipkin-server.cfapps.io/">Zipkin for Brewery on PWS</a>, its <a href="https://github.com/spring-cloud-samples/brewery">Github Code</a>.
Ensure that you&#8217;ve picked the lookback period of 7 days. If there are no traces, go to <a href="https://docsbrewing-presenting.cfapps.io/">Presenting application</a>
and order some beers. Then check Zipkin for traces.</p>
</li>
</ul>
</div>
</div>
</div>
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