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@@ -55,7 +55,9 @@ For instance, you can insert additional properties from a different server or fr
}
}</pre><p>The <code class="literal">Environment</code> that is passed in is the one for the <code class="literal">ApplicationContext</code> about to be created&#8201;&#8212;&#8201;in other words, the one for which we supply additional property sources for.
It already has its normal Spring Boot-provided property sources, so you can use those to locate a property source specific to this <code class="literal">Environment</code> (for example, by keying it on <code class="literal">spring.application.name</code>, as is done in the default Spring Cloud Config Server property source locator).</p><p>If you create a jar with this class in it and then add a <code class="literal">META-INF/spring.factories</code> containing the following, the <code class="literal">customProperty</code> <code class="literal">PropertySource</code> appears in any application that includes that jar on its classpath:</p><pre class="screen">org.springframework.cloud.bootstrap.BootstrapConfiguration=sample.custom.CustomPropertySourceLocator</pre></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_environment_changes" href="#_environment_changes"></a>1.7&nbsp;Environment Changes</h2></div></div></div><p>The application listens for an <code class="literal">EnvironmentChangeEvent</code> and reacts to the change in a couple of standard ways (additional <code class="literal">ApplicationListeners</code> can be added as <code class="literal">@Beans</code> by the user in the normal way).
It already has its normal Spring Boot-provided property sources, so you can use those to locate a property source specific to this <code class="literal">Environment</code> (for example, by keying it on <code class="literal">spring.application.name</code>, as is done in the default Spring Cloud Config Server property source locator).</p><p>If you create a jar with this class in it and then add a <code class="literal">META-INF/spring.factories</code> containing the following, the <code class="literal">customProperty</code> <code class="literal">PropertySource</code> appears in any application that includes that jar on its classpath:</p><pre class="screen">org.springframework.cloud.bootstrap.BootstrapConfiguration=sample.custom.CustomPropertySourceLocator</pre></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_logging_configuration" href="#_logging_configuration"></a>1.7&nbsp;Logging Configuration</h2></div></div></div><p>If you are going to use Spring Boot to configure log settings than
you should place this configuration in `bootstrap.[yml | properties]
if you would like it to apply to all events.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_environment_changes" href="#_environment_changes"></a>1.8&nbsp;Environment Changes</h2></div></div></div><p>The application listens for an <code class="literal">EnvironmentChangeEvent</code> and reacts to the change in a couple of standard ways (additional <code class="literal">ApplicationListeners</code> can be added as <code class="literal">@Beans</code> by the user in the normal way).
When an <code class="literal">EnvironmentChangeEvent</code> is observed, it has a list of key values that have changed, and the application uses those to:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Re-bind any <code class="literal">@ConfigurationProperties</code> beans in the context</li><li class="listitem">Set the logger levels for any properties in <code class="literal">logging.level.*</code></li></ul></div><p>Note that the Config Client does not, by default, poll for changes in the <code class="literal">Environment</code>.
Generally, we would not recommend that approach for detecting changes (although you could set it up with a
<code class="literal">@Scheduled</code> annotation).
@@ -64,7 +66,7 @@ Note that those APIs are public and part of core Spring).
You can verify that the changes are bound to <code class="literal">@ConfigurationProperties</code> beans by visiting the <code class="literal">/configprops</code> endpoint (a normal Spring Boot Actuator feature).
For instance, a <code class="literal">DataSource</code> can have its <code class="literal">maxPoolSize</code> changed at runtime (the default <code class="literal">DataSource</code> created by Spring Boot is an <code class="literal">@ConfigurationProperties</code> bean) and grow capacity dynamically.
Re-binding <code class="literal">@ConfigurationProperties</code> does not cover another large class of use cases, where you need more control over the refresh and where you need a change to be atomic over the whole <code class="literal">ApplicationContext</code>.
To address those concerns, we have <code class="literal">@RefreshScope</code>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_refresh_scope" href="#_refresh_scope"></a>1.8&nbsp;Refresh Scope</h2></div></div></div><p>When there is a configuration change, a Spring <code class="literal">@Bean</code> that is marked as <code class="literal">@RefreshScope</code> gets special treatment.
To address those concerns, we have <code class="literal">@RefreshScope</code>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_refresh_scope" href="#_refresh_scope"></a>1.9&nbsp;Refresh Scope</h2></div></div></div><p>When there is a configuration change, a Spring <code class="literal">@Bean</code> that is marked as <code class="literal">@RefreshScope</code> gets special treatment.
This feature addresses the problem of stateful beans that only get their configuration injected when they are initialized.
For instance, if a <code class="literal">DataSource</code> has open connections when the database URL is changed via the <code class="literal">Environment</code>, you probably want the holders of those connections to be able to complete what they are doing.
Then, the next time something borrows a connection from the pool, it gets one with the new URL.</p><p>Sometimes, it might even be mandatory to apply the <code class="literal">@RefreshScope</code>
@@ -81,9 +83,9 @@ To refresh an individual bean by name, there is also a <code class="literal">ref
<span xmlns:d="http://docbook.org/ns/docbook" class="hl-attribute"> include</span>: refresh</pre><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><code class="literal">@RefreshScope</code> works (technically) on an <code class="literal">@Configuration</code> class, but it might lead to surprising behavior.
For example, it does not mean that all the <code class="literal">@Beans</code> defined in that class are themselves in <code class="literal">@RefreshScope</code>.
Specifically, anything that depends on those beans cannot rely on them being updated when a refresh is initiated, unless it is itself in <code class="literal">@RefreshScope</code>.
In that case, it is rebuilt on a refresh and its dependencies are re-injected. At that point, they are re-initialized from the refreshed <code class="literal">@Configuration</code>).</p></td></tr></table></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_encryption_and_decryption" href="#_encryption_and_decryption"></a>1.9&nbsp;Encryption and Decryption</h2></div></div></div><p>Spring Cloud has an <code class="literal">Environment</code> pre-processor for decrypting property values locally.
In that case, it is rebuilt on a refresh and its dependencies are re-injected. At that point, they are re-initialized from the refreshed <code class="literal">@Configuration</code>).</p></td></tr></table></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_encryption_and_decryption" href="#_encryption_and_decryption"></a>1.10&nbsp;Encryption and Decryption</h2></div></div></div><p>Spring Cloud has an <code class="literal">Environment</code> pre-processor for decrypting property values locally.
It follows the same rules as the Config Server and has the same external configuration through <code class="literal">encrypt.*</code>.
Thus, you can use encrypted values in the form of <code class="literal">{cipher}*</code> and, as long as there is a valid key, they are decrypted before the main application context gets the <code class="literal">Environment</code> settings.
To use the encryption features in an application, you need to include Spring Security RSA in your classpath (Maven co-ordinates: "org.springframework.security:spring-security-rsa"), and you also need the full strength JCE extensions in your JVM.</p><p>If you get an exception due to "Illegal key size" and you use Sun&#8217;s JDK, you need to install the Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files.
See the following links for more information:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="link" href="http://www.oracle.com/technetwork/java/javase/downloads/jce-6-download-429243.html" target="_top">Java 6 JCE</a></li><li class="listitem"><a class="link" href="http://www.oracle.com/technetwork/java/javase/downloads/jce-7-download-432124.html" target="_top">Java 7 JCE</a></li><li class="listitem"><a class="link" href="http://www.oracle.com/technetwork/java/javase/downloads/jce8-download-2133166.html" target="_top">Java 8 JCE</a></li></ul></div><p>Extract the files into the JDK/jre/lib/security folder for whichever version of JRE/JDK x64/x86 you use.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_endpoints" href="#_endpoints"></a>1.10&nbsp;Endpoints</h2></div></div></div><p>For a Spring Boot Actuator application, some additional management endpoints are available. You can use:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><code class="literal">POST</code> to <code class="literal">/actuator/env</code> to update the <code class="literal">Environment</code> and rebind <code class="literal">@ConfigurationProperties</code> and log levels.</li><li class="listitem"><code class="literal">/actuator/refresh</code> to re-load the boot strap context and refresh the <code class="literal">@RefreshScope</code> beans.</li><li class="listitem"><code class="literal">/actuator/restart</code> to close the <code class="literal">ApplicationContext</code> and restart it (disabled by default).</li><li class="listitem"><code class="literal">/actuator/pause</code> and <code class="literal">/actuator/resume</code> for calling the <code class="literal">Lifecycle</code> methods (<code class="literal">stop()</code> and <code class="literal">start()</code> on the <code class="literal">ApplicationContext</code>).</li></ul></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>If you disable the <code class="literal">/actuator/restart</code> endpoint then the <code class="literal">/actuator/pause</code> and <code class="literal">/actuator/resume</code> endpoints
See the following links for more information:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="link" href="http://www.oracle.com/technetwork/java/javase/downloads/jce-6-download-429243.html" target="_top">Java 6 JCE</a></li><li class="listitem"><a class="link" href="http://www.oracle.com/technetwork/java/javase/downloads/jce-7-download-432124.html" target="_top">Java 7 JCE</a></li><li class="listitem"><a class="link" href="http://www.oracle.com/technetwork/java/javase/downloads/jce8-download-2133166.html" target="_top">Java 8 JCE</a></li></ul></div><p>Extract the files into the JDK/jre/lib/security folder for whichever version of JRE/JDK x64/x86 you use.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_endpoints" href="#_endpoints"></a>1.11&nbsp;Endpoints</h2></div></div></div><p>For a Spring Boot Actuator application, some additional management endpoints are available. You can use:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><code class="literal">POST</code> to <code class="literal">/actuator/env</code> to update the <code class="literal">Environment</code> and rebind <code class="literal">@ConfigurationProperties</code> and log levels.</li><li class="listitem"><code class="literal">/actuator/refresh</code> to re-load the boot strap context and refresh the <code class="literal">@RefreshScope</code> beans.</li><li class="listitem"><code class="literal">/actuator/restart</code> to close the <code class="literal">ApplicationContext</code> and restart it (disabled by default).</li><li class="listitem"><code class="literal">/actuator/pause</code> and <code class="literal">/actuator/resume</code> for calling the <code class="literal">Lifecycle</code> methods (<code class="literal">stop()</code> and <code class="literal">start()</code> on the <code class="literal">ApplicationContext</code>).</li></ul></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>If you disable the <code class="literal">/actuator/restart</code> endpoint then the <code class="literal">/actuator/pause</code> and <code class="literal">/actuator/resume</code> endpoints
will also be disabled since they are just a special case of <code class="literal">/actuator/restart</code>.</p></td></tr></table></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi_pr01.html">Prev</a>&nbsp;</td><td width="20%" align="center">&nbsp;</td><td width="40%" align="right">&nbsp;<a accesskey="n" href="multi__spring_cloud_commons_common_abstractions.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">&nbsp;</td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-commons.html">Home</a></td><td width="40%" align="right" valign="top">&nbsp;2.&nbsp;Spring Cloud Commons: Common Abstractions</td></tr></table></div></body></html>

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<html><head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Cloud Native Applications</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>Cloud Native Applications</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="#_spring_cloud_context_application_context_services">1. Spring Cloud Context: Application Context Services</a></span></dt><dd><dl><dt><span class="section"><a href="#_the_bootstrap_application_context">1.1. The Bootstrap Application Context</a></span></dt><dt><span class="section"><a href="#_application_context_hierarchies">1.2. Application Context Hierarchies</a></span></dt><dt><span class="section"><a href="#customizing-bootstrap-properties">1.3. Changing the Location of Bootstrap Properties</a></span></dt><dt><span class="section"><a href="#overriding-bootstrap-properties">1.4. Overriding the Values of Remote Properties</a></span></dt><dt><span class="section"><a href="#_customizing_the_bootstrap_configuration">1.5. Customizing the Bootstrap Configuration</a></span></dt><dt><span class="section"><a href="#customizing-bootstrap-property-sources">1.6. Customizing the Bootstrap Property Sources</a></span></dt><dt><span class="section"><a href="#_environment_changes">1.7. Environment Changes</a></span></dt><dt><span class="section"><a href="#_refresh_scope">1.8. Refresh Scope</a></span></dt><dt><span class="section"><a href="#_encryption_and_decryption">1.9. Encryption and Decryption</a></span></dt><dt><span class="section"><a href="#_endpoints">1.10. Endpoints</a></span></dt></dl></dd><dt><span class="chapter"><a href="#_spring_cloud_commons_common_abstractions">2. Spring Cloud Commons: Common Abstractions</a></span></dt><dd><dl><dt><span class="section"><a href="#__enablediscoveryclient">2.1. @EnableDiscoveryClient</a></span></dt><dd><dl><dt><span class="section"><a href="#_health_indicator">2.1.1. Health Indicator</a></span></dt></dl></dd><dt><span class="section"><a href="#_serviceregistry">2.2. ServiceRegistry</a></span></dt><dd><dl><dt><span class="section"><a href="#_serviceregistry_auto_registration">2.2.1. ServiceRegistry Auto-Registration</a></span></dt><dt><span class="section"><a href="#_service_registry_actuator_endpoint">2.2.2. Service Registry Actuator Endpoint</a></span></dt></dl></dd><dt><span class="section"><a href="#_spring_resttemplate_as_a_load_balancer_client">2.3. Spring RestTemplate as a Load Balancer Client</a></span></dt><dt><span class="section"><a href="#_spring_webclient_as_a_load_balancer_client">2.4. Spring WebClient as a Load Balancer Client</a></span></dt><dd><dl><dt><span class="section"><a href="#_retrying_failed_requests">2.4.1. Retrying Failed Requests</a></span></dt></dl></dd><dt><span class="section"><a href="#_multiple_resttemplate_objects">2.5. Multiple RestTemplate objects</a></span></dt><dt><span class="section"><a href="#loadbalanced-webclient">2.6. Spring WebFlux WebClient as a Load Balancer Client</a></span></dt><dt><span class="section"><a href="#ignore-network-interfaces">2.7. Ignore Network Interfaces</a></span></dt><dt><span class="section"><a href="#http-clients">2.8. HTTP Client Factories</a></span></dt><dt><span class="section"><a href="#enabled-features">2.9. Enabled Features</a></span></dt><dd><dl><dt><span class="section"><a href="#_feature_types">2.9.1. Feature types</a></span></dt><dt><span class="section"><a href="#_declaring_features">2.9.2. Declaring features</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><a class="link" href="http://pivotal.io/platform-as-a-service/migrating-to-cloud-native-application-architectures-ebook" target="_top">Cloud Native</a> is a style of application development that encourages easy adoption of best practices in the areas of continuous delivery and value-driven development.
<title>Cloud Native Applications</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>Cloud Native Applications</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="#_spring_cloud_context_application_context_services">1. Spring Cloud Context: Application Context Services</a></span></dt><dd><dl><dt><span class="section"><a href="#_the_bootstrap_application_context">1.1. The Bootstrap Application Context</a></span></dt><dt><span class="section"><a href="#_application_context_hierarchies">1.2. Application Context Hierarchies</a></span></dt><dt><span class="section"><a href="#customizing-bootstrap-properties">1.3. Changing the Location of Bootstrap Properties</a></span></dt><dt><span class="section"><a href="#overriding-bootstrap-properties">1.4. Overriding the Values of Remote Properties</a></span></dt><dt><span class="section"><a href="#_customizing_the_bootstrap_configuration">1.5. Customizing the Bootstrap Configuration</a></span></dt><dt><span class="section"><a href="#customizing-bootstrap-property-sources">1.6. Customizing the Bootstrap Property Sources</a></span></dt><dt><span class="section"><a href="#_logging_configuration">1.7. Logging Configuration</a></span></dt><dt><span class="section"><a href="#_environment_changes">1.8. Environment Changes</a></span></dt><dt><span class="section"><a href="#_refresh_scope">1.9. Refresh Scope</a></span></dt><dt><span class="section"><a href="#_encryption_and_decryption">1.10. Encryption and Decryption</a></span></dt><dt><span class="section"><a href="#_endpoints">1.11. Endpoints</a></span></dt></dl></dd><dt><span class="chapter"><a href="#_spring_cloud_commons_common_abstractions">2. Spring Cloud Commons: Common Abstractions</a></span></dt><dd><dl><dt><span class="section"><a href="#__enablediscoveryclient">2.1. @EnableDiscoveryClient</a></span></dt><dd><dl><dt><span class="section"><a href="#_health_indicator">2.1.1. Health Indicator</a></span></dt></dl></dd><dt><span class="section"><a href="#_serviceregistry">2.2. ServiceRegistry</a></span></dt><dd><dl><dt><span class="section"><a href="#_serviceregistry_auto_registration">2.2.1. ServiceRegistry Auto-Registration</a></span></dt><dt><span class="section"><a href="#_service_registry_actuator_endpoint">2.2.2. Service Registry Actuator Endpoint</a></span></dt></dl></dd><dt><span class="section"><a href="#_spring_resttemplate_as_a_load_balancer_client">2.3. Spring RestTemplate as a Load Balancer Client</a></span></dt><dt><span class="section"><a href="#_spring_webclient_as_a_load_balancer_client">2.4. Spring WebClient as a Load Balancer Client</a></span></dt><dd><dl><dt><span class="section"><a href="#_retrying_failed_requests">2.4.1. Retrying Failed Requests</a></span></dt></dl></dd><dt><span class="section"><a href="#_multiple_resttemplate_objects">2.5. Multiple RestTemplate objects</a></span></dt><dt><span class="section"><a href="#loadbalanced-webclient">2.6. Spring WebFlux WebClient as a Load Balancer Client</a></span></dt><dt><span class="section"><a href="#ignore-network-interfaces">2.7. Ignore Network Interfaces</a></span></dt><dt><span class="section"><a href="#http-clients">2.8. HTTP Client Factories</a></span></dt><dt><span class="section"><a href="#enabled-features">2.9. Enabled Features</a></span></dt><dd><dl><dt><span class="section"><a href="#_feature_types">2.9.1. Feature types</a></span></dt><dt><span class="section"><a href="#_declaring_features">2.9.2. Declaring features</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><a class="link" href="http://pivotal.io/platform-as-a-service/migrating-to-cloud-native-application-architectures-ebook" target="_top">Cloud Native</a> is a style of application development that encourages easy adoption of best practices in the areas of continuous delivery and value-driven development.
A related discipline is that of building <a class="link" href="http://12factor.net/" target="_top">12-factor Applications</a>, in which development practices are aligned with delivery and operations goals&#8201;&#8212;&#8201;for instance, by using declarative programming and management and monitoring.
Spring Cloud facilitates these styles of development in a number of specific ways.
The starting point is a set of features to which all components in a distributed system need easy access.</p><p>Many of those features are covered by <a class="link" href="http://projects.spring.io/spring-boot" target="_top">Spring Boot</a>, on which Spring Cloud builds. Some more features are delivered by Spring Cloud as two libraries: Spring Cloud Context and Spring Cloud Commons.
@@ -61,7 +61,9 @@ For instance, you can insert additional properties from a different server or fr
}
}</pre><p>The <code class="literal">Environment</code> that is passed in is the one for the <code class="literal">ApplicationContext</code> about to be created&#8201;&#8212;&#8201;in other words, the one for which we supply additional property sources for.
It already has its normal Spring Boot-provided property sources, so you can use those to locate a property source specific to this <code class="literal">Environment</code> (for example, by keying it on <code class="literal">spring.application.name</code>, as is done in the default Spring Cloud Config Server property source locator).</p><p>If you create a jar with this class in it and then add a <code class="literal">META-INF/spring.factories</code> containing the following, the <code class="literal">customProperty</code> <code class="literal">PropertySource</code> appears in any application that includes that jar on its classpath:</p><pre class="screen">org.springframework.cloud.bootstrap.BootstrapConfiguration=sample.custom.CustomPropertySourceLocator</pre></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_environment_changes" href="#_environment_changes"></a>1.7&nbsp;Environment Changes</h2></div></div></div><p>The application listens for an <code class="literal">EnvironmentChangeEvent</code> and reacts to the change in a couple of standard ways (additional <code class="literal">ApplicationListeners</code> can be added as <code class="literal">@Beans</code> by the user in the normal way).
It already has its normal Spring Boot-provided property sources, so you can use those to locate a property source specific to this <code class="literal">Environment</code> (for example, by keying it on <code class="literal">spring.application.name</code>, as is done in the default Spring Cloud Config Server property source locator).</p><p>If you create a jar with this class in it and then add a <code class="literal">META-INF/spring.factories</code> containing the following, the <code class="literal">customProperty</code> <code class="literal">PropertySource</code> appears in any application that includes that jar on its classpath:</p><pre class="screen">org.springframework.cloud.bootstrap.BootstrapConfiguration=sample.custom.CustomPropertySourceLocator</pre></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_logging_configuration" href="#_logging_configuration"></a>1.7&nbsp;Logging Configuration</h2></div></div></div><p>If you are going to use Spring Boot to configure log settings than
you should place this configuration in `bootstrap.[yml | properties]
if you would like it to apply to all events.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_environment_changes" href="#_environment_changes"></a>1.8&nbsp;Environment Changes</h2></div></div></div><p>The application listens for an <code class="literal">EnvironmentChangeEvent</code> and reacts to the change in a couple of standard ways (additional <code class="literal">ApplicationListeners</code> can be added as <code class="literal">@Beans</code> by the user in the normal way).
When an <code class="literal">EnvironmentChangeEvent</code> is observed, it has a list of key values that have changed, and the application uses those to:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Re-bind any <code class="literal">@ConfigurationProperties</code> beans in the context</li><li class="listitem">Set the logger levels for any properties in <code class="literal">logging.level.*</code></li></ul></div><p>Note that the Config Client does not, by default, poll for changes in the <code class="literal">Environment</code>.
Generally, we would not recommend that approach for detecting changes (although you could set it up with a
<code class="literal">@Scheduled</code> annotation).
@@ -70,7 +72,7 @@ Note that those APIs are public and part of core Spring).
You can verify that the changes are bound to <code class="literal">@ConfigurationProperties</code> beans by visiting the <code class="literal">/configprops</code> endpoint (a normal Spring Boot Actuator feature).
For instance, a <code class="literal">DataSource</code> can have its <code class="literal">maxPoolSize</code> changed at runtime (the default <code class="literal">DataSource</code> created by Spring Boot is an <code class="literal">@ConfigurationProperties</code> bean) and grow capacity dynamically.
Re-binding <code class="literal">@ConfigurationProperties</code> does not cover another large class of use cases, where you need more control over the refresh and where you need a change to be atomic over the whole <code class="literal">ApplicationContext</code>.
To address those concerns, we have <code class="literal">@RefreshScope</code>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_refresh_scope" href="#_refresh_scope"></a>1.8&nbsp;Refresh Scope</h2></div></div></div><p>When there is a configuration change, a Spring <code class="literal">@Bean</code> that is marked as <code class="literal">@RefreshScope</code> gets special treatment.
To address those concerns, we have <code class="literal">@RefreshScope</code>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_refresh_scope" href="#_refresh_scope"></a>1.9&nbsp;Refresh Scope</h2></div></div></div><p>When there is a configuration change, a Spring <code class="literal">@Bean</code> that is marked as <code class="literal">@RefreshScope</code> gets special treatment.
This feature addresses the problem of stateful beans that only get their configuration injected when they are initialized.
For instance, if a <code class="literal">DataSource</code> has open connections when the database URL is changed via the <code class="literal">Environment</code>, you probably want the holders of those connections to be able to complete what they are doing.
Then, the next time something borrows a connection from the pool, it gets one with the new URL.</p><p>Sometimes, it might even be mandatory to apply the <code class="literal">@RefreshScope</code>
@@ -87,11 +89,11 @@ To refresh an individual bean by name, there is also a <code class="literal">ref
<span xmlns:d="http://docbook.org/ns/docbook" class="hl-attribute"> include</span>: refresh</pre><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><code class="literal">@RefreshScope</code> works (technically) on an <code class="literal">@Configuration</code> class, but it might lead to surprising behavior.
For example, it does not mean that all the <code class="literal">@Beans</code> defined in that class are themselves in <code class="literal">@RefreshScope</code>.
Specifically, anything that depends on those beans cannot rely on them being updated when a refresh is initiated, unless it is itself in <code class="literal">@RefreshScope</code>.
In that case, it is rebuilt on a refresh and its dependencies are re-injected. At that point, they are re-initialized from the refreshed <code class="literal">@Configuration</code>).</p></td></tr></table></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_encryption_and_decryption" href="#_encryption_and_decryption"></a>1.9&nbsp;Encryption and Decryption</h2></div></div></div><p>Spring Cloud has an <code class="literal">Environment</code> pre-processor for decrypting property values locally.
In that case, it is rebuilt on a refresh and its dependencies are re-injected. At that point, they are re-initialized from the refreshed <code class="literal">@Configuration</code>).</p></td></tr></table></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_encryption_and_decryption" href="#_encryption_and_decryption"></a>1.10&nbsp;Encryption and Decryption</h2></div></div></div><p>Spring Cloud has an <code class="literal">Environment</code> pre-processor for decrypting property values locally.
It follows the same rules as the Config Server and has the same external configuration through <code class="literal">encrypt.*</code>.
Thus, you can use encrypted values in the form of <code class="literal">{cipher}*</code> and, as long as there is a valid key, they are decrypted before the main application context gets the <code class="literal">Environment</code> settings.
To use the encryption features in an application, you need to include Spring Security RSA in your classpath (Maven co-ordinates: "org.springframework.security:spring-security-rsa"), and you also need the full strength JCE extensions in your JVM.</p><p>If you get an exception due to "Illegal key size" and you use Sun&#8217;s JDK, you need to install the Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files.
See the following links for more information:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="link" href="http://www.oracle.com/technetwork/java/javase/downloads/jce-6-download-429243.html" target="_top">Java 6 JCE</a></li><li class="listitem"><a class="link" href="http://www.oracle.com/technetwork/java/javase/downloads/jce-7-download-432124.html" target="_top">Java 7 JCE</a></li><li class="listitem"><a class="link" href="http://www.oracle.com/technetwork/java/javase/downloads/jce8-download-2133166.html" target="_top">Java 8 JCE</a></li></ul></div><p>Extract the files into the JDK/jre/lib/security folder for whichever version of JRE/JDK x64/x86 you use.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_endpoints" href="#_endpoints"></a>1.10&nbsp;Endpoints</h2></div></div></div><p>For a Spring Boot Actuator application, some additional management endpoints are available. You can use:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><code class="literal">POST</code> to <code class="literal">/actuator/env</code> to update the <code class="literal">Environment</code> and rebind <code class="literal">@ConfigurationProperties</code> and log levels.</li><li class="listitem"><code class="literal">/actuator/refresh</code> to re-load the boot strap context and refresh the <code class="literal">@RefreshScope</code> beans.</li><li class="listitem"><code class="literal">/actuator/restart</code> to close the <code class="literal">ApplicationContext</code> and restart it (disabled by default).</li><li class="listitem"><code class="literal">/actuator/pause</code> and <code class="literal">/actuator/resume</code> for calling the <code class="literal">Lifecycle</code> methods (<code class="literal">stop()</code> and <code class="literal">start()</code> on the <code class="literal">ApplicationContext</code>).</li></ul></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>If you disable the <code class="literal">/actuator/restart</code> endpoint then the <code class="literal">/actuator/pause</code> and <code class="literal">/actuator/resume</code> endpoints
See the following links for more information:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="link" href="http://www.oracle.com/technetwork/java/javase/downloads/jce-6-download-429243.html" target="_top">Java 6 JCE</a></li><li class="listitem"><a class="link" href="http://www.oracle.com/technetwork/java/javase/downloads/jce-7-download-432124.html" target="_top">Java 7 JCE</a></li><li class="listitem"><a class="link" href="http://www.oracle.com/technetwork/java/javase/downloads/jce8-download-2133166.html" target="_top">Java 8 JCE</a></li></ul></div><p>Extract the files into the JDK/jre/lib/security folder for whichever version of JRE/JDK x64/x86 you use.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_endpoints" href="#_endpoints"></a>1.11&nbsp;Endpoints</h2></div></div></div><p>For a Spring Boot Actuator application, some additional management endpoints are available. You can use:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><code class="literal">POST</code> to <code class="literal">/actuator/env</code> to update the <code class="literal">Environment</code> and rebind <code class="literal">@ConfigurationProperties</code> and log levels.</li><li class="listitem"><code class="literal">/actuator/refresh</code> to re-load the boot strap context and refresh the <code class="literal">@RefreshScope</code> beans.</li><li class="listitem"><code class="literal">/actuator/restart</code> to close the <code class="literal">ApplicationContext</code> and restart it (disabled by default).</li><li class="listitem"><code class="literal">/actuator/pause</code> and <code class="literal">/actuator/resume</code> for calling the <code class="literal">Lifecycle</code> methods (<code class="literal">stop()</code> and <code class="literal">start()</code> on the <code class="literal">ApplicationContext</code>).</li></ul></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>If you disable the <code class="literal">/actuator/restart</code> endpoint then the <code class="literal">/actuator/pause</code> and <code class="literal">/actuator/resume</code> endpoints
will also be disabled since they are just a special case of <code class="literal">/actuator/restart</code>.</p></td></tr></table></div></div></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="_spring_cloud_commons_common_abstractions" href="#_spring_cloud_commons_common_abstractions"></a>2.&nbsp;Spring Cloud Commons: Common Abstractions</h1></div></div></div><p>Patterns such as service discovery, load balancing, and circuit breakers lend themselves to a common abstraction layer that can be consumed by all Spring Cloud clients, independent of the implementation (for example, discovery with Eureka or Consul).</p><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="__enablediscoveryclient" href="#__enablediscoveryclient"></a>2.1&nbsp;@EnableDiscoveryClient</h2></div></div></div><p>Spring Cloud Commons provides the <code class="literal">@EnableDiscoveryClient</code> annotation.
This looks for implementations of the <code class="literal">DiscoveryClient</code> interface with <code class="literal">META-INF/spring.factories</code>.
Implementations of the Discovery Client add a configuration class to <code class="literal">spring.factories</code> under the <code class="literal">org.springframework.cloud.client.discovery.EnableDiscoveryClient</code> key.

6
spring-cloud-commons.xml
View File

@@ -150,6 +150,12 @@ It already has its normal Spring Boot-provided property sources, so you can use
<simpara>If you create a jar with this class in it and then add a <literal>META-INF/spring.factories</literal> containing the following, the <literal>customProperty</literal> <literal>PropertySource</literal> appears in any application that includes that jar on its classpath:</simpara>
<screen>org.springframework.cloud.bootstrap.BootstrapConfiguration=sample.custom.CustomPropertySourceLocator</screen>
</section>
<section xml:id="_logging_configuration">
<title>Logging Configuration</title>
<simpara>If you are going to use Spring Boot to configure log settings than
you should place this configuration in `bootstrap.[yml | properties]
if you would like it to apply to all events.</simpara>
</section>
<section xml:id="_environment_changes">
<title>Environment Changes</title>
<simpara>The application listens for an <literal>EnvironmentChangeEvent</literal> and reacts to the change in a couple of standard ways (additional <literal>ApplicationListeners</literal> can be added as <literal>@Beans</literal> by the user in the normal way).