253 lines
8.6 KiB
HTML
253 lines
8.6 KiB
HTML
<!DOCTYPE html>
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<title>Introduction</title>
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</head>
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<body class="book toc2 toc-left">
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<div id="header">
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<div id="toc" class="toc2">
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<div id="toctitle">Table of Contents</div>
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<ul class="sectlevel1">
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<li><a href="#_introduction">Introduction</a>
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<ul class="sectlevel2">
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<li><a href="#_supported_implementations">Supported Implementations</a></li>
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</ul>
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</li>
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<li><a href="#_core_concepts">Core Concepts</a>
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<ul class="sectlevel2">
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<li><a href="#_circuit_breakers_in_reactive_code">Circuit Breakers In Reactive Code</a></li>
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</ul>
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</li>
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<li><a href="#_configuration">Configuration</a></li>
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</ul>
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</div>
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</div>
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<div id="content">
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<div class="sect1">
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<h2 id="_introduction"><a class="link" href="#_introduction">Introduction</a></h2>
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<div class="sectionbody">
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<div class="paragraph">
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<p>Spring Cloud Circuit breaker provides an abstraction across different circuit breaker implementations.
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It provides a consistent API to use in your applications allowing you the developer to choose the circuit breaker implementation that best fits your needs for your app.</p>
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</div>
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<div class="sect2">
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<h3 id="_supported_implementations"><a class="link" href="#_supported_implementations">Supported Implementations</a></h3>
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<div class="ulist">
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<ul>
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<li>
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<p><a href="https://github.com/Netflix/Hystrix">Netfix Hystrix</a></p>
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</li>
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<li>
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<p><a href="https://github.com/resilience4j/resilience4j">Resilience4J</a></p>
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</li>
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<li>
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<p><a href="https://github.com/alibaba/Sentinel">Sentinel</a></p>
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</li>
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<li>
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<p><a href="https://github.com/spring-projects/spring-retry">Spring Retry</a></p>
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</li>
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</ul>
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</div>
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</div>
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</div>
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</div>
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<div class="sect1">
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<h2 id="_core_concepts"><a class="link" href="#_core_concepts">Core Concepts</a></h2>
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<div class="sectionbody">
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<div class="paragraph">
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<p>To create a circuit breaker in your code you can use the <code>CircuitBreakerFactory</code> API. When you include a Spring Cloud Circuit Breaker starter on your classpath a bean implementing this API will automatically be created for you.
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A very simple example of using this API is given below</p>
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</div>
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<div class="exampleblock">
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<div class="content">
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<div class="listingblock">
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<div class="content">
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<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@Service
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public static class DemoControllerService {
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private RestTemplate rest;
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private CircuitBreakerFactory cbFactory;
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public DemoControllerService(RestTemplate rest, CircuitBreakerFactory cbFactory) {
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this.rest = rest;
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this.cbFactory = cbFactory;
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}
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public String slow() {
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return cbFactory.create("slow").run(() -> rest.getForObject("/slow", String.class), throwable -> "fallback");
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}
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}</code></pre>
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</div>
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</div>
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</div>
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</div>
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<div class="paragraph">
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<p>The <code>CircuitBreakerFactory.create</code> API will create an instance of a class called <code>CircuitBreaker</code>.
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The <code>run</code> method takes a <code>Supplier</code> and a <code>Function</code>.
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The <code>Supplier</code> is the code that you are going to wrap in a circuit breaker.
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The <code>Function</code> is the fallback that will be executed if the circuit breaker is tripped.
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The function will be passed the <code>Throwable</code> that caused the fallback to be triggered.
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You can optionally exclude the fallback if you do not want to provide one.</p>
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</div>
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<div class="sect2">
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<h3 id="_circuit_breakers_in_reactive_code"><a class="link" href="#_circuit_breakers_in_reactive_code">Circuit Breakers In Reactive Code</a></h3>
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<div class="paragraph">
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<p>If Project Reactor is on the class path then you can also use <code>ReactiveCircuitBreakerFactory</code> for your reactive code.</p>
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</div>
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<div class="exampleblock">
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<div class="content">
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<div class="listingblock">
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<div class="content">
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<pre class="highlightjs highlight"><code class="language-java hljs" data-lang="java">@Service
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public static class DemoControllerService {
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private ReactiveCircuitBreakerFactory cbFactory;
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private WebClient webClient;
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public DemoControllerService(WebClient webClient, ReactiveCircuitBreakerFactory cbFactory) {
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this.webClient = webClient;
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this.cbFactory = cbFactory;
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}
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public Mono<String> slow() {
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return webClient.get().uri("/slow").retrieve().bodyToMono(String.class).transform(
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it -> cbFactory.create("slow").run(it, throwable -> return Mono.just("fallback")));
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}
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}</code></pre>
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</div>
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</div>
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</div>
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</div>
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<div class="paragraph">
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<p>The <code>ReactiveCircuitBreakerFactory.create</code> API will create an instance of a class called <code>ReactiveCircuitBreaker</code>.
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The <code>run</code> method takes with a <code>Mono</code> or <code>Flux</code> and wraps it in a circuit breaker.
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You can optionally profile a fallback <code>Function</code> which will be called if the circuit breaker is tripped and will be passed the <code>Throwable</code>
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that caused the failure.</p>
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</div>
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</div>
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</div>
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</div>
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<div class="sect1">
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<h2 id="_configuration"><a class="link" href="#_configuration">Configuration</a></h2>
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<div class="sectionbody">
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<div class="paragraph">
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<p>You can configure your circuit breakers using by creating beans of type <code>Customizer</code>.
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The <code>Customizer</code> interface has a single method called <code>customize</code> that takes in the <code>Object</code> to customize.</p>
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</div>
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<div class="paragraph">
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<p>For detailed information on how to customize a given implementation see
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the links below</p>
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</div>
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<div class="ulist">
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<ul>
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<li>
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<p><a href="../../../spring-cloud-netflix/reference/html/#_circuit_breaker_spring_cloud_circuit_breaker_with_hystrix">Hystrix</a></p>
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</li>
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<li>
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<p><a href="../../../spring-cloud-circuitbreaker/reference/html/spring-cloud-circuitbreaker.html#_configuring_resilience4j_circuit_breakers">Resilience4J</a></p>
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</li>
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<li>
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<p><a href="../../../spring-cloud-circuitbreaker/reference/html/spring-cloud-circuitbreaker.html#_configuring_sentinel_circuit_breakers">Sentinal</a></p>
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</li>
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<li>
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<p><a href="../../../spring-cloud-circuitbreaker/reference/html/spring-cloud-circuitbreaker.html#_configuring_spring_retry_circuit_breakers">Spring Retry</a></p>
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</li>
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</ul>
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</div>
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</div>
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</div>
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</div>
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