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<title>Spring Cloud Function</title><link rel="stylesheet" type="text/css" href="css/manual-singlepage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div lang="en" class="book"><div class="titlepage"><div><div><h1 class="title"><a name="d0e3"></a>Spring Cloud Function</h1></div></div><hr></div><div class="toc"><p><b>Table of Contents</b></p><dl class="toc"><dt><span class="preface"><a href="#d0e9"></a></span></dt><dt><span class="chapter"><a href="#_introduction">1. Introduction</a></span></dt><dt><span class="chapter"><a href="#_getting_started">2. Getting Started</a></span></dt><dt><span class="chapter"><a href="#_building_and_running_a_function">3. Building and Running a Function</a></span></dt><dt><span class="chapter"><a href="#_dynamic_compilation">4. Dynamic Compilation</a></span></dt><dd><dl><dt><span class="section"><a href="#_start_the_function_registry_service">4.1. Start the Function Registry Service:</a></span></dt><dt><span class="section"><a href="#_register_a_function">4.2. Register a Function:</a></span></dt><dt><span class="section"><a href="#_run_a_rest_microservice_using_that_function">4.3. Run a REST Microservice using that Function:</a></span></dt><dt><span class="section"><a href="#_register_a_supplier">4.4. Register a Supplier:</a></span></dt><dt><span class="section"><a href="#_run_a_rest_microservice_using_that_supplier">4.5. Run a REST Microservice using that Supplier:</a></span></dt><dt><span class="section"><a href="#_register_a_consumer">4.6. Register a Consumer:</a></span></dt><dt><span class="section"><a href="#_run_a_rest_microservice_using_that_consumer">4.7. Run a REST Microservice using that Consumer:</a></span></dt><dt><span class="section"><a href="#_run_stream_processing_microservices">4.8. Run Stream Processing Microservices:</a></span></dt></dl></dd><dt><span class="chapter"><a href="#_function_catalog_and_flexible_function_signatures">5. Function Catalog and Flexible Function Signatures</a></span></dt><dt><span class="chapter"><a href="#_standalone_web_applications">6. Standalone Web Applications</a></span></dt><dt><span class="chapter"><a href="#_standalone_streaming_applications">7. Standalone Streaming Applications</a></span></dt><dt><span class="chapter"><a href="#_deploying_a_packaged_function">8. Deploying a Packaged Function</a></span></dt><dt><span class="chapter"><a href="#_serverless_platform_adapters">9. Serverless Platform Adapters</a></span></dt><dd><dl><dt><span class="section"><a href="#_aws_lambda">9.1. AWS Lambda</a></span></dt><dd><dl><dt><span class="section"><a href="#_introduction_2">9.1.1. Introduction</a></span></dt><dd><dl><dt><span class="section"><a href="#_notes_on_jar_layout">Notes on JAR Layout</a></span></dt></dl></dd><dt><span class="section"><a href="#_build">9.1.2. Build</a></span></dt><dt><span class="section"><a href="#_upload">9.1.3. Upload</a></span></dt></dl></dd><dt><span class="section"><a href="#_azure_functions">9.2. Azure Functions</a></span></dt><dd><dl><dt><span class="section"><a href="#_notes_on_jar_layout_2">9.2.1. Notes on JAR Layout</a></span></dt><dt><span class="section"><a href="#_json_configuration">9.2.2. JSON Configuration</a></span></dt><dt><span class="section"><a href="#_build_2">9.2.3. Build</a></span></dt><dt><span class="section"><a href="#_running_the_sample">9.2.4. Running the sample</a></span></dt></dl></dd><dt><span class="section"><a href="#_apache_openwhisk">9.3. Apache Openwhisk</a></span></dt><dd><dl><dt><span class="section"><a href="#_quick_start">9.3.1. Quick Start</a></span></dt></dl></dd></dl></dd></dl></div><div class="preface"><div class="titlepage"><div><div><h1 class="title"><a name="d0e9" href="#d0e9"></a></h1></div></div></div><p>Mark Fisher, Dave Syer</p><p></p></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="_introduction" href="#_introduction"></a>1. Introduction</h1></div></div></div><p>Spring Cloud Function is a project with the following high-level goals:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="emphasis"><em>Promote the implementation of business logic via functions.</em></span></li><li class="listitem"><span class="emphasis"><em>Decouple the development lifecycle of business logic from any specific runtime target so that the same code can run as a web endpoint, a stream processor, or a task.</em></span></li><li class="listitem"><span class="emphasis"><em>Support a uniform programming model across serverless providers, as well as the ability to run standalone (locally or in a PaaS).</em></span></li><li class="listitem"><span class="emphasis"><em>Enable Spring Boot features (auto-configuration, dependency injection, metrics) on serverless providers.</em></span></li></ul></div><p>It abstracts away all of the transport details and
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infrastructure, allowing the developer to keep all the familiar tools
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and processes, and focus firmly on business logic.</p><p>Here’s a complete, executable, testable Spring Boot application
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(implementing a simple string manipulation):</p><pre class="programlisting"><em><span class="hl-annotation" style="color: gray">@SpringBootApplication</span></em>
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<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">public</span> <span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">class</span> Application {
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<em><span class="hl-annotation" style="color: gray">@Bean</span></em>
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<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">public</span> Function<Flux<String>, Flux<String>> uppercase() {
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<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">return</span> flux -> flux.map(value -> value.toUpperCase());
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}
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<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">public</span> <span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">static</span> <span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">void</span> main(String[] args) {
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SpringApplication.run(Application.<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">class</span>, args);
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}
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}</pre><p>It’s just a Spring Boot application, so it can be built, run and
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tested, locally and in a CI build, the same way as any other Spring
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Boot application. The <code class="literal">Function</code> is from <code class="literal">java.util</code> and <code class="literal">Flux</code> is a
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<a class="link" href="http://www.reactive-streams.org/" target="_top">Reactive Streams</a> <code class="literal">Publisher</code> from
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<a class="link" href="https://projectreactor.io/" target="_top">Project Reactor</a>. The function can be
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accessed over HTTP or messaging.</p><p>Spring Cloud Function has 4 main features:</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">Wrappers for <code class="literal">@Beans</code> of type <code class="literal">Function</code>, <code class="literal">Consumer</code> and
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<code class="literal">Supplier</code>, exposing them to the outside world as either HTTP
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endpoints and/or message stream listeners/publishers with RabbitMQ, Kafka etc.</li><li class="listitem">Compiling strings which are Java function bodies into bytecode, and
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then turning them into <code class="literal">@Beans</code> that can be wrapped as above.</li><li class="listitem">Deploying a JAR file containing such an application context with an
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isolated classloader, so that you can pack them together in a single
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JVM.</li><li class="listitem">Adapters for <a class="link" href="https://github.com/spring-cloud/spring-cloud-function/tree/master/spring-cloud-function-adapters/spring-cloud-function-adapter-aws" target="_top">AWS Lambda</a>, <a class="link" href="https://github.com/spring-cloud/spring-cloud-function/tree/master/spring-cloud-function-adapters/spring-cloud-function-adapter-azure" target="_top">Azure</a>, <a class="link" href="https://github.com/spring-cloud/spring-cloud-function/tree/master/spring-cloud-function-adapters/spring-cloud-function-adapter-openwhisk" target="_top">Apache OpenWhisk</a> and possibly other "serverless" service providers.</li></ol></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="images/note.png"></td><th align="left">Note</th></tr><tr><td align="left" valign="top"><p>Spring Cloud is released under the non-restrictive Apache 2.0 license. If you would like to contribute to this section of the documentation or if you find an error, please find the source code and issue trackers in the project at <a class="link" href="https://github.com/spring-cloud/spring-cloud-function/tree/master/docs/src/main/asciidoc" target="_top">github</a>.</p></td></tr></table></div></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="_getting_started" href="#_getting_started"></a>2. Getting Started</h1></div></div></div><p>Build from the command line (and "install" the samples):</p><pre class="screen">$ ./mvnw clean install</pre><p>(If you like to YOLO add <code class="literal">-DskipTests</code>.)</p><p>Run one of the samples, e.g.</p><pre class="screen">$ java -jar spring-cloud-function-samples/function-sample/target/*.jar</pre><p>This runs the app and exposes its functions over HTTP, so you can
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convert a string to uppercase, like this:</p><pre class="screen">$ curl -H "Content-Type: text/plain" localhost:8080/uppercase -d Hello
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HELLO</pre><p>You can convert multiple strings (a <code class="literal">Flux<String></code>) by separating them
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with new lines</p><pre class="screen">$ curl -H "Content-Type: text/plain" localhost:8080/uppercase -d 'Hello
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> World'
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HELLOWORLD</pre><p>(You can use <code class="literal"><sup>Q</sup>J</code> in a terminal to insert a new line in a literal
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string like that.)</p></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="_building_and_running_a_function" href="#_building_and_running_a_function"></a>3. Building and Running a Function</h1></div></div></div><p>The sample <code class="literal">@SpringBootApplication</code> above has a function that can be
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decorated at runtime by Spring Cloud Function to be an HTTP endpoint,
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or a Stream processor, for instance with RabbitMQ, Apache Kafka or
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JMS.</p><p>The <code class="literal">@Beans</code> can be <code class="literal">Function</code>, <code class="literal">Consumer</code> or <code class="literal">Supplier</code> (all from
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<code class="literal">java.util</code>), and their parametric types can be String or POJO. A
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<code class="literal">Function</code> is exposed as a Spring Cloud Stream <code class="literal">Processor</code> if
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<code class="literal">spring-cloud-function-stream</code> is on the classpath.
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A <code class="literal">Consumer</code> is also exposed as a Stream
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<code class="literal">Sink</code> and a <code class="literal">Supplier</code> translates to a Stream <code class="literal">Source</code>.
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HTTP endpoints are exposed if the Stream binder is <code class="literal">spring-cloud-stream-binder-servlet</code>.</p><p>Functions can be of <code class="literal">Flux<String></code> or <code class="literal">Flux<Pojo></code> and Spring Cloud
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Function takes care of converting the data to and from the desired
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types, as long as it comes in as plain text or (in the case of the
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POJO) JSON. TBD: support for <code class="literal">Flux<Message<Pojo>></code> and maybe plain
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<code class="literal">Pojo</code> types (Fluxes implied and implemented by the framework).</p><p>Functions can be grouped together in a single application, or deployed
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one-per-jar. It’s up to the developer to choose. An app with multiple
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functions can be deployed multiple times in different "personalities",
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exposing different functions over different physical transports.</p></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="_dynamic_compilation" href="#_dynamic_compilation"></a>4. Dynamic Compilation</h1></div></div></div><p>There is a sample app that uses the function compiler to create a
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function from a configuration property. The vanilla "function-sample"
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also has that feature. And there are some examples that you can run to
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see the compilation happening at run time. To run these examples,
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change into the <code class="literal">scripts</code> directory:</p><pre class="screen">cd scripts</pre><p>Also, start a RabbitMQ server locally (e.g. execute <code class="literal">rabbitmq-server</code>).</p><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_start_the_function_registry_service" href="#_start_the_function_registry_service"></a>4.1 Start the Function Registry Service:</h2></div></div></div><pre class="screen">./function-registry.sh</pre></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_register_a_function" href="#_register_a_function"></a>4.2 Register a Function:</h2></div></div></div><pre class="screen">./registerFunction.sh -n uppercase -f "f->f.map(s->s.toString().toUpperCase())"</pre></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_run_a_rest_microservice_using_that_function" href="#_run_a_rest_microservice_using_that_function"></a>4.3 Run a REST Microservice using that Function:</h2></div></div></div><pre class="screen">./web.sh -f uppercase -p 9000
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curl -H "Content-Type: text/plain" -H "Accept: text/plain" localhost:9000/uppercase -d foo</pre></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_register_a_supplier" href="#_register_a_supplier"></a>4.4 Register a Supplier:</h2></div></div></div><pre class="screen">./registerSupplier.sh -n words -f "()->Flux.just(\"foo\",\"bar\")"</pre></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_run_a_rest_microservice_using_that_supplier" href="#_run_a_rest_microservice_using_that_supplier"></a>4.5 Run a REST Microservice using that Supplier:</h2></div></div></div><pre class="screen">./web.sh -s words -p 9001
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curl -H "Accept: application/json" localhost:9001/words</pre></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_register_a_consumer" href="#_register_a_consumer"></a>4.6 Register a Consumer:</h2></div></div></div><pre class="screen">./registerConsumer.sh -n print -t String -f "System.out::println"</pre></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_run_a_rest_microservice_using_that_consumer" href="#_run_a_rest_microservice_using_that_consumer"></a>4.7 Run a REST Microservice using that Consumer:</h2></div></div></div><pre class="screen">./web.sh -c print -p 9002
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curl -X POST -H "Content-Type: text/plain" -d foo localhost:9002/print</pre></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_run_stream_processing_microservices" href="#_run_stream_processing_microservices"></a>4.8 Run Stream Processing Microservices:</h2></div></div></div><p>First register a streaming words supplier:</p><pre class="screen">./registerSupplier.sh -n wordstream -f "()->Flux.interval(Duration.ofMillis(1000)).map(i->\"message-\"+i)"</pre><p>Then start the source (supplier), processor (function), and sink (consumer) apps
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(in reverse order):</p><pre class="screen">./stream.sh -p 9103 -i uppercaseWords -c print
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./stream.sh -p 9102 -i words -f uppercase -o uppercaseWords
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./stream.sh -p 9101 -s wordstream -o words</pre><p>The output will appear in the console of the sink app (one message per second, converted to uppercase):</p><pre class="screen">MESSAGE-0
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MESSAGE-1
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MESSAGE-2
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MESSAGE-3
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MESSAGE-4
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MESSAGE-5
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MESSAGE-6
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MESSAGE-7
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MESSAGE-8
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MESSAGE-9
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...</pre></div></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="_function_catalog_and_flexible_function_signatures" href="#_function_catalog_and_flexible_function_signatures"></a>5. Function Catalog and Flexible Function Signatures</h1></div></div></div><p>One of the main features of Spring Cloud Function is to adapt and
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support a range of type signatures for user-defined functions. So
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users can supply a bean of type <code class="literal">Function<String,String></code>, for
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instance, and the <code class="literal">FunctionCatalog</code> will wrap it into a
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<code class="literal">Function<Flux<String>,Flux<String>></code>. Users don’t normally have to
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care about the <code class="literal">FunctionCatalog</code> at all, but it is useful to know what
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kind of functions are supported in user code.</p><p>Generally speaking users can expect that if they write a function for
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a plain old Java type (or primitive wrapper), then the function
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catalog will wrap it to a <code class="literal">Flux</code> of the same type. If the user writes
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a function using <code class="literal">Message</code> (from spring-messaging) it will receive and
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transmit headers from any adapter that supports key-value metadata
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(e.g. HTTP headers). Here are the details.</p><div class="informaltable"><table style="border-collapse: collapse;border-top: 0.5pt solid ; border-bottom: 0.5pt solid ; border-left: 0.5pt solid ; border-right: 0.5pt solid ; "><colgroup><col class="col_1"><col class="col_2"><col class="col_3"></colgroup><thead><tr><th style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top">User Function</th><th style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top">Catalog Registration</th><th style="border-bottom: 0.5pt solid ; " align="left" valign="top"> </th></tr></thead><tbody><tr><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p><code class="literal">Function<S,T></code></p></td><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p><code class="literal">Function<Flux<S>, Flux<T>></code></p></td><td style="border-bottom: 0.5pt solid ; " align="left" valign="top"> </td></tr><tr><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p><code class="literal">Function<Message<S>,Message<T>></code></p></td><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p><code class="literal">Function<Flux<Message<S>>, Flux<Message<T>>></code></p></td><td style="border-bottom: 0.5pt solid ; " align="left" valign="top"> </td></tr><tr><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p><code class="literal">Function<Flux<S>, Flux<T>></code></p></td><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p><code class="literal">Function<Flux<S>, Flux<T>></code> (pass through)</p></td><td style="border-bottom: 0.5pt solid ; " align="left" valign="top"> </td></tr><tr><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p><code class="literal">Supplier<T></code></p></td><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p><code class="literal">Supplier<Flux<T>></code></p></td><td style="border-bottom: 0.5pt solid ; " align="left" valign="top"> </td></tr><tr><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p><code class="literal">Supplier<Flux<T>></code></p></td><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p><code class="literal">Supplier<Flux<T>></code></p></td><td style="border-bottom: 0.5pt solid ; " align="left" valign="top"> </td></tr><tr><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p><code class="literal">Consumer<T></code></p></td><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p><code class="literal">Function<Flux<T>, Mono<Void>></code></p></td><td style="border-bottom: 0.5pt solid ; " align="left" valign="top"> </td></tr><tr><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p><code class="literal">Consumer<Message<T>></code></p></td><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p><code class="literal">Function<Flux<Message<T>>, Mono<Void>></code></p></td><td style="border-bottom: 0.5pt solid ; " align="left" valign="top"> </td></tr><tr><td style="border-right: 0.5pt solid ; " align="left" valign="top"><p><code class="literal">Consumer<Flux<T>></code></p></td><td style="border-right: 0.5pt solid ; " align="left" valign="top"><p><code class="literal">Consumer<Flux<T>></code></p></td><td style="" align="left" valign="top"> </td></tr></tbody></table></div><p>Consumer is a little bit special because it has a <code class="literal">void</code> return type,
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which implies blocking, at least potentially. Most likely you will not
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need to write <code class="literal">Consumer<Flux<?>></code>, but if you do need to do that,
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remember to subscribe to the input flux. If you declare a <code class="literal">Consumer</code>
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of a non publisher type (which is normal), it will be converted to a
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function that returns a publisher, so that it can be subscribed to in
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a controlled way.</p><p>A function catalog can contain a <code class="literal">Supplier</code> and a <code class="literal">Function</code> (or
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<code class="literal">Consumer</code>) with the same name (like a GET and a POST to the same
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resource). It can even contain a <code class="literal">Consumer<Flux<>></code> with the same name
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as a <code class="literal">Function</code>, but it cannot contain a <code class="literal">Consumer<T></code> and a
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<code class="literal">Function<T,S></code> with the same name when <code class="literal">T</code> is not a <code class="literal">Publisher</code>
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because the consumer would be converted to a <code class="literal">Function</code> and only one
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of them can be registered.</p></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="_standalone_web_applications" href="#_standalone_web_applications"></a>6. Standalone Web Applications</h1></div></div></div><p>The <code class="literal">spring-cloud-function-web</code> module has autoconfiguration that
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activates when it is included in a Spring Boot web application (with
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MVC support). There is also a <code class="literal">spring-cloud-starter-function-web</code> to
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collect all the optional dependnecies in case you just want a simple
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getting started experience.</p><p>With the web configurations activated your app will have an MVC
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endpoint (on "/" by default, but configurable with
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<code class="literal">spring.cloud.function.web.path</code>) that can be used to access the
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functions in the application context. The supported content types are
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plain text and JSON.</p><div class="informaltable"><table style="border-collapse: collapse;border-top: 0.5pt solid ; border-bottom: 0.5pt solid ; border-left: 0.5pt solid ; border-right: 0.5pt solid ; "><colgroup><col class="col_1"><col class="col_2"><col class="col_3"><col class="col_4"><col class="col_5"></colgroup><thead><tr><th style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top">Method</th><th style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top">Path</th><th style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top">Request</th><th style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top">Response</th><th style="border-bottom: 0.5pt solid ; " align="left" valign="top">Status</th></tr></thead><tbody><tr><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p>GET</p></td><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p>/{supplier}</p></td><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p>-</p></td><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p>Items from the named supplier</p></td><td style="border-bottom: 0.5pt solid ; " align="left" valign="top"><p>200 OK</p></td></tr><tr><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p>POST</p></td><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p>/{consumer}</p></td><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p>JSON object or text</p></td><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p>Mirrors input and pushes request body into consumer</p></td><td style="border-bottom: 0.5pt solid ; " align="left" valign="top"><p>202 Accepted</p></td></tr><tr><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p>POST</p></td><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p>/{consumer}</p></td><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p>JSON array or text with new lines</p></td><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p>Mirrors input and pushes body into consumer one by one</p></td><td style="border-bottom: 0.5pt solid ; " align="left" valign="top"><p>202 Accepted</p></td></tr><tr><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p>POST</p></td><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p>/{function}</p></td><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p>JSON object or text</p></td><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p>The result of applying the named function</p></td><td style="border-bottom: 0.5pt solid ; " align="left" valign="top"><p>200 OK</p></td></tr><tr><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p>POST</p></td><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p>/{function}</p></td><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p>JSON array or text with new lines</p></td><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p>The result of applying the named function</p></td><td style="border-bottom: 0.5pt solid ; " align="left" valign="top"><p>200 OK</p></td></tr><tr><td style="border-right: 0.5pt solid ; " align="left" valign="top"><p>GET</p></td><td style="border-right: 0.5pt solid ; " align="left" valign="top"><p>/{function}/{item}</p></td><td style="border-right: 0.5pt solid ; " align="left" valign="top"><p>-</p></td><td style="border-right: 0.5pt solid ; " align="left" valign="top"><p>Convert the item into an object and return the result of applying the function</p></td><td style="" align="left" valign="top"><p>200 OK</p></td></tr></tbody></table></div><p>As the table above shows the behaviour of the endpoint depends on the method and also the type of incoming request data. When the incoming data is single valued, and the target function is declared as obviously single valued (i.e. not returning a collection or <code class="literal">Flux</code>), then the response will also contain a single value. For multi-valued responses the client can ask for a server-sent event stream by sending `Accept: text/event-stream". If there is only one function (consumer etc.) then the name in the path is optional. Composite functions can be addressed using pipes or commas to separate function names (pipes are legal in URL paths, but a bit awkward to type on the command line).</p><p>Functions and consumers that are declared with input and output in <code class="literal">Message<?></code> will see the request headers on the input messages, and the output message headers will be converted to HTTP headers.</p><p>When POSTing text the response format might be different with Spring Boot 2.0 and older versions, depending on the content negotiation (provide content type and accpt headers for the best results).</p></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="_standalone_streaming_applications" href="#_standalone_streaming_applications"></a>7. Standalone Streaming Applications</h1></div></div></div><p>To send or receive messages from a broker (such as RabbitMQ or Kafka) you can use the <code class="literal">spring-cloud-function-stream</code> adapter. Add the adapter to your classpath along with the appropriate binder from Spring Cloud Stream. The adapter will bind to the message broker as a <code class="literal">Processor</code> (input and output streams) unless the user explicitly disables one or the other using <code class="literal">spring.cloud.function.stream.{source,sink}.enabled=false</code>.</p><p>An incoming message is routed to a function (or consumer). If there is only one, then the choice is obvious. If there are multiple functions that can accept an incoming message, the message is inspected to see if there is a <code class="literal">stream_routekey</code> header containing the name of a function. Routing headers or function names can be composed using a comma- or pipe-separated name. The header is also added to outgoing messages from a supplier. Messages with no route key can be routed exclusively to a function or consumer by specifying <code class="literal">spring.cloud.function.stream.{processor,sink}.name</code>. If a single function cannot be identified to process an incoming message there will be an error, unless you set <code class="literal">spring.cloud.function.stream.shared=true</code>, in which case such messages will be sent to all compatible functions. A single supplier can be chosen for output messages from a supplier (if more than one is available) using the <code class="literal">spring.cloud.function.stream.source.name</code>.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="images/note.png"></td><th align="left">Note</th></tr><tr><td align="left" valign="top"><p>some binders will fail on startup if the message broker is not available and the function catalog contains suppliers that immediately produce messages when accessed. You can switch off the automatic publishing from suppliers on startup using the <code class="literal">spring.cloud.function.strean.supplier.enabled=false</code> flag.</p></td></tr></table></div></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="_deploying_a_packaged_function" href="#_deploying_a_packaged_function"></a>8. Deploying a Packaged Function</h1></div></div></div><p>Spring Cloud Function provides a "deployer" library that allows you to launch a jar file (or exploded archive, or set of jar files) with an isolated class loader and expose the functions defined in it. This is quite a powerful tool that would allow you to, for instance, adapt a function to a range of different input-output adapters without changing the target jar file. Serverless platforms often have this kind of feature built in, so you could see it as a building block for a function invoker in such a platform (indeed the <a class="link" href="https://projectriff.io" target="_top">Riff</a> Java function invoker uses this library).</p><p>The standard entry point of the API is the Spring configuration annotation <code class="literal">@EnableFunctionDeployer</code>. If that is used in a Spring Boot application the deployer kicks in and looks for some configuration to tell it where to find the function jar. At a minimum the user has to provide a <code class="literal">function.location</code> which is a URL or resource location for the archive containing the functions. It can optionally use a <code class="literal">maven:</code> prefix to locate the artifact via a dependency lookup (see <code class="literal">FunctionProperties</code> for complete details). A Spring Boot application is bootstrapped from the jar file, using the <code class="literal">MANIFEST.MF</code> to locate a start class, so that a standard Spring Boot fat jar works well, for example. If the target jar can be launched successfully then the result is a function registered in the main application’s <code class="literal">FunctionCatalog</code>. The registered function can be applied by code in the main application, even though it was created in an isolated class loader (by deault).</p></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="_serverless_platform_adapters" href="#_serverless_platform_adapters"></a>9. Serverless Platform Adapters</h1></div></div></div><p>As well as being able to run as a standalone process, a Spring Cloud
|
|
Function application can be adapted to run one of the existing
|
|
serverless platforms. In the project there are adapters for
|
|
<a class="link" href="https://github.com/spring-cloud/spring-cloud-function/tree/master/spring-cloud-function-adapters/spring-cloud-function-adapter-aws" target="_top">AWS
|
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Lambda</a>,
|
|
<a class="link" href="https://github.com/spring-cloud/spring-cloud-function/tree/master/spring-cloud-function-adapters/spring-cloud-function-adapter-azure" target="_top">Azure</a>,
|
|
and
|
|
<a class="link" href="https://github.com/spring-cloud/spring-cloud-function/tree/master/spring-cloud-function-adapters/spring-cloud-function-adapter-openwhisk" target="_top">Apache
|
|
OpenWhisk</a>. The <a class="link" href="https://github.com/fnproject/fn" target="_top">Oracle Fn platform</a>
|
|
has its own Spring Cloud Function adapter. And
|
|
<a class="link" href="https://projectriff.io" target="_top">Riff</a> supports Java functions and its
|
|
<a class="link" href="https://github.com/projectriff/java-function-invoker" target="_top">Java Function
|
|
Invoker</a> acts natively is an adapter for Spring Cloud Function jars.</p><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_aws_lambda" href="#_aws_lambda"></a>9.1 AWS Lambda</h2></div></div></div><p>The <a class="link" href="https://aws.amazon.com/" target="_top">AWS</a> adapter takes a Spring Cloud Function app and converts it to a form that can run in AWS Lambda.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_introduction_2" href="#_introduction_2"></a>9.1.1 Introduction</h3></div></div></div><p>The adapter has a couple of generic request handlers that you can use. The most generic is <code class="literal">SpringBootStreamHandler</code>, which uses a Jackson <code class="literal">ObjectMapper</code> provided by Spring Boot to serialize and deserialize the objects in the function. There is also a <code class="literal">SpringBootRequestHandler</code> which you can extend, and provide the input and output types as type parameters (enabling AWS to inspect the class and do the JSON conversions itself).</p><p>If your app has more than one <code class="literal">@Bean</code> of type <code class="literal">Function</code> etc. then you can choose the one to use by configuring <code class="literal">function.name</code> (e.g. as <code class="literal">FUNCTION_NAME</code> environment variable in AWS). The functions are extracted from the Spring Cloud <code class="literal">FunctionCatalog</code> (searching first for <code class="literal">Function</code> then <code class="literal">Consumer</code> and finally <code class="literal">Supplier</code>).</p><div class="section"><div class="titlepage"><div><div><h4 class="title"><a name="_notes_on_jar_layout" href="#_notes_on_jar_layout"></a>Notes on JAR Layout</h4></div></div></div><p>You don’t need the Spring Cloud Function Web or Stream adapter at runtime in Lambda, so you might need to exclude those before you create the JAR you send to AWS. A Lambda application has to be shaded, but a Spring Boot standalone application does not, so you can run the same app using 2 separate jars (as per the sample here). The sample app creates 2 jar files, one with an <code class="literal">aws</code> classifier for deploying in Lambda, and one executable (thin) jar that includes <code class="literal">spring-cloud-function-web</code> at runtime. Spring Cloud Function will try and locate a "main class" for you from the JAR file manifest, using the <code class="literal">Start-Class</code> attribute (which will be added for you by the Spring Boot tooling if you use the starter parent). If there is no <code class="literal">Start-Class</code> in your manifest you can use an environment variable <code class="literal">MAIN_CLASS</code> when you deploy the function to AWS.</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_build" href="#_build"></a>9.1.2 Build</h3></div></div></div><pre class="screen">./mvnw -U clean package</pre></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_upload" href="#_upload"></a>9.1.3 Upload</h3></div></div></div><p>Build the sample under <code class="literal">spring-cloud-function-samples/function-sample-aws</code> and upload the <code class="literal">-aws</code> jar file to Lambda. The handler can be <code class="literal">example.Handler</code> or <code class="literal">org.springframework.cloud.function.adapter.aws.SpringBootStreamHandler</code> (FQN of the class, <span class="emphasis"><em>not</em></span> a method reference, although Lambda does accept method references).</p><p>Using the AWS command line tools it looks like this:</p><pre class="screen">aws lambda create-function --function-name Uppercase --role arn:aws:iam::[USERID]:role/service-role/[ROLE] --zip-file fileb://function-sample-aws/target/function-sample-aws-1.0.0.BUILD-SNAPSHOT-aws.jar --handler org.springframework.cloud.function.adapter.aws.SpringBootStreamHandler --description "Spring Cloud Function Adapter Example" --runtime java8 --region us-east-1 --timeout 30 --memory-size 1024 --publish</pre><p>The input type for the function in the AWS sample is a Foo with a single property called "value". So you would need this to test it:</p><pre class="screen">{
|
|
"value": "test"
|
|
}</pre></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_azure_functions" href="#_azure_functions"></a>9.2 Azure Functions</h2></div></div></div><p>The <a class="link" href="https://azure.microsoft.com" target="_top">Azure</a> adapter bootstraps a Spring Cloud Function context and channels function calls from the Azure framework into the user functions, using Spring Boot configuration where necessary. Azure Functions has quite a unique, but invasive programming model, involving annotations in user code that are specific to the platform. The Spring Cloud Function Azure adapter trades the convenience of these annotations for portability of the function implementations. Instead of using the annotations you have to write some JSON by hand (at least for now) to guide the platform to call the right methods in the adapter.</p><p>The adapter has a generic http request handler that you can use.
|
|
There is a <code class="literal">AzureSpringBootRequestHandler</code> which you must extend, and provide the input and output types as type parameters (enabling Azure to inspect the class and do the JSON conversions itself).</p><p>If your app has more than one <code class="literal">@Bean</code> of type <code class="literal">Function</code> etc. then you can choose the one to use by configuring <code class="literal">function.name</code>.
|
|
The functions are extracted from the Spring Cloud <code class="literal">FunctionCatalog</code>.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_notes_on_jar_layout_2" href="#_notes_on_jar_layout_2"></a>9.2.1 Notes on JAR Layout</h3></div></div></div><p>You don’t need the Spring Cloud Function Web at runtime in Azure, so you need to exclude this before you create the JAR you deploy to Azure.
|
|
A function application on Azure has to be shaded, but a Spring Boot standalone application does not, so you can run the same app using 2 separate jars (as per the sample here).
|
|
The sample app creates the shaded jar file, with an <code class="literal">azure</code> classifier for deploying in Azure.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_json_configuration" href="#_json_configuration"></a>9.2.2 JSON Configuration</h3></div></div></div><p>The Azure tooling needs to find some JSON configuration files to tell it how to deploy and integrate the function (e.g. which Java class to use as the entry point, and which triggers to use). Those files can be created with the Maven plugin for a non-Spring function, but the tooling doesn’t work yet with the adapter in its current form. There is an example <code class="literal">function.json</code> in the sample which hooks the function up as an HTTP endpoint:</p><pre class="screen">{
|
|
"scriptFile" : "../function-sample-azure-1.0.0.BUILD-SNAPSHOT-azure.jar",
|
|
"entryPoint" : "example.FooHandler.execute",
|
|
"bindings" : [ {
|
|
"type" : "httpTrigger",
|
|
"name" : "foo",
|
|
"direction" : "in",
|
|
"authLevel" : "anonymous",
|
|
"methods" : [ "get", "post" ]
|
|
}, {
|
|
"type" : "http",
|
|
"name" : "$return",
|
|
"direction" : "out"
|
|
} ],
|
|
"disabled" : false
|
|
}</pre></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_build_2" href="#_build_2"></a>9.2.3 Build</h3></div></div></div><pre class="screen">./mvnw -U clean package</pre></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_running_the_sample" href="#_running_the_sample"></a>9.2.4 Running the sample</h3></div></div></div><p>You can run the sample locally, just like the other Spring Cloud Function samples:</p><p></p><p></p><p>and <code class="literal">curl -H "Content-Type: text/plain" localhost:8080/function -d '{"value": "hello foobar"}'</code>.</p><p>You will need the <code class="literal">az</code> CLI app and some node.js fu (see <a class="link" href="https://docs.microsoft.com/en-us/azure/azure-functions/functions-create-first-java-maven" target="_top">https://docs.microsoft.com/en-us/azure/azure-functions/functions-create-first-java-maven</a> for more detail). To deploy the function on Azure runtime:</p><pre class="screen">$ az login
|
|
$ mvn azure-functions:deploy</pre><p>On another terminal try this: <code class="literal">curl <a class="link" href="https://<azure-function-url-from-the-log>/api/uppercase" target="_top">https://<azure-function-url-from-the-log>/api/uppercase</a> -d '{"value": "hello foobar!"}'</code>. Please ensure that you use the right URL for the function above. Alternatively you can test the function in the Azure Dashboard UI (click on the function name, go to the right hand side and click "Test" and to the bottom right, "Run").</p><p>The input type for the function in the Azure sample is a Foo with a single property called "value". So you need this to test it with something like below:</p><pre class="screen">{
|
|
"value": "foobar"
|
|
}</pre></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_apache_openwhisk" href="#_apache_openwhisk"></a>9.3 Apache Openwhisk</h2></div></div></div><p>The <a class="link" href="https://openwhisk.apache.org/" target="_top">OpenWhisk</a> adapter is in the form of an executable jar that can be used in a a docker image to be deployed to Openwhisk. The platform works in request-response mode, listening on port 8080 on a specific endpoint, so the adapter is a simple Spring MVC application.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_quick_start" href="#_quick_start"></a>9.3.1 Quick Start</h3></div></div></div><p>Implement a POF (be sure to use the <code class="literal">functions</code> package):</p><pre class="screen">package functions;
|
|
|
|
import java.util.function.Function;
|
|
|
|
public class Uppercase implements Function<String, String> {
|
|
|
|
public String apply(String input) {
|
|
return input.toUpperCase();
|
|
}
|
|
}</pre><p>Install it into your local Maven repository:</p><pre class="screen">./mvnw clean install</pre><p>Create a <code class="literal">function.properties</code> file that provides its Maven coordinates. For example:</p><pre class="screen">dependencies.function: com.example:pof:0.0.1-SNAPSHOT</pre><p>Copy the openwhisk runner JAR to the working directory (same directory as the properties file):</p><pre class="screen">cp spring-cloud-function-adapters/spring-cloud-function-adapter-openwhisk/target/spring-cloud-function-adapter-openwhisk-1.0.0.BUILD-SNAPSHOT.jar runner.jar</pre><p>Generate a m2 repo from the <code class="literal">--thin.dryrun</code> of the runner JAR with the above properties file:</p><pre class="screen">java -jar -Dthin.root=m2 runner.jar --thin.name=function --thin.dryrun</pre><p>Use the following Dockerfile:</p><pre class="screen">FROM openjdk:8-jdk-alpine
|
|
VOLUME /tmp
|
|
COPY m2 /m2
|
|
ADD runner.jar .
|
|
ADD function.properties .
|
|
ENV JAVA_OPTS=""
|
|
ENTRYPOINT [ "java", "-Djava.security.egd=file:/dev/./urandom", "-jar", "runner.jar", "--thin.root=/m2", "--thin.name=function", "--function.name=uppercase"]
|
|
EXPOSE 8080</pre><div class="blockquote"><blockquote class="blockquote"><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="images/note.png"></td><th align="left">Note</th></tr><tr><td align="left" valign="top"><p>you could use a Spring Cloud Function app, instead of just a jar with a POF in it, in which case you would have to change the way the app runs in the container so that it picks up the main class as a source file. For example, you could change the <code class="literal">ENTRYPOINT</code> above and add <code class="literal">--spring.main.sources=com.example.SampleApplication</code>.</p></td></tr></table></div></blockquote></div><p>Build the Docker image:</p><pre class="screen">docker build -t [username/appname] .</pre><p>Push the Docker image:</p><pre class="screen">docker push [username/appname]</pre><p>Use the OpenWhisk CLI (e.g. after <code class="literal">vagrant ssh</code>) to create the action:</p><pre class="screen">wsk action create example --docker [username/appname]</pre><p>Invoke the action:</p><pre class="screen">wsk action invoke example --result --param payload foo
|
|
{
|
|
"result": "FOO"
|
|
}</pre></div></div></div></div></body></html> |