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19 lines
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<title>Spring Cloud Gateway</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 Gateway</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="#gateway-starter">1. How to Include Spring Cloud Gateway</a></span></dt><dt><span class="chapter"><a href="#_building_a_gateway_using_spring_mvc">2. Building a Gateway Using Spring MVC</a></span></dt></dl></div><div class="preface"><div class="titlepage"><div><div><h1 class="title"><a name="d0e9" href="#d0e9"></a></h1></div></div></div><p><span class="strong"><strong>1.0.3.BUILD-SNAPSHOT</strong></span></p><p>This project provides a library for building an API Gateway on top of Spring MVC. Spring Cloud Gateway aims to provide a simple, yet effective way to route to APIs and provide cross cutting concerns to them such as: security, monitoring/metrics, and resiliency.</p></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="gateway-starter" href="#gateway-starter"></a>1. How to Include Spring Cloud Gateway</h1></div></div></div><p>To include Spring Cloud Gateway in your project add a dependency with group <code class="literal">org.springframework.cloud</code> and artifact id <code class="literal">spring-cloud-gateway-mvc</code>. See the <a class="link" href="http://projects.spring.io/spring-cloud/" target="_top">Spring Cloud Project page</a> for details on setting up your build system with the current Spring Cloud Release Train.</p></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="_building_a_gateway_using_spring_mvc" href="#_building_a_gateway_using_spring_mvc"></a>2. Building a Gateway Using Spring MVC</h1></div></div></div><p>Spring Cloud Gateway provides a utility object called <code class="literal">ProxyExchange</code> which you can use inside a regular Spring MVC handler as a method parameter. It supports basic downstream HTTP exchanges via methods that mirror the HTTP verbs, or forwarding to a local handler via the <code class="literal">forward()</code> method.</p><p>Example (proxying a request to "/test" downstream to a remote server):</p><pre class="programlisting"><em><span class="hl-annotation" style="color: gray">@RestController</span></em>
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<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> GatewaySampleApplication {
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<em><span class="hl-annotation" style="color: gray">@Value("${remote.home}")</span></em>
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<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">private</span> URI home;
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<em><span class="hl-annotation" style="color: gray">@GetMapping("/test")</span></em>
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<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">public</span> ResponseEntity<?> proxy(ProxyExchange<Object> proxy) <span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">throws</span> Exception {
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<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">return</span> proxy.uri(home.toString() + <span xmlns:d="http://docbook.org/ns/docbook" class="hl-string">"/image/png"</span>).get();
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}
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}</pre><p>There are convenience methods on the <code class="literal">ProxyExchange</code> to enable the handler method to discover and enhance the URI path of the incoming request. For example you might want to extract the trailing elements of a path to pass them downstream:</p><pre class="programlisting"><em><span class="hl-annotation" style="color: gray">@GetMapping("/proxy/path/**")</span></em>
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<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">public</span> ResponseEntity<?> proxyPath(ProxyExchange<?> proxy) <span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">throws</span> Exception {
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String path = proxy.path(<span xmlns:d="http://docbook.org/ns/docbook" class="hl-string">"/proxy/path/"</span>);
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<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">return</span> proxy.uri(home.toString() + <span xmlns:d="http://docbook.org/ns/docbook" class="hl-string">"/foos/"</span> + path).get();
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}</pre><p>All the features of Spring MVC are available to Gateway handler methods. So you can inject request headers and query parameters, for instance, and you can constrain the incoming requests with declarations in the mapping annotation. See the documentation for <code class="literal">@RequestMapping</code> in Spring MVC for more details of those features.</p><p>Headers can be added to the downstream response using the <code class="literal">header()</code> methods on <code class="literal">ProxyExchange</code>.</p><p>You can also manipulate response headers (and anything else you like in the response) by adding a mapper to the <code class="literal">get()</code> etc. method. The mapper is a <code class="literal">Function</code> that takes the incoming <code class="literal">ResponseEntity</code> and converts it to an outgoing one.</p><p>First class support is provided for "sensitive" headers ("cookie" and "authorization" by default) which are not passed downstream, and for "proxy" headers (<code class="literal">x-forwarded-*</code>).</p></div></div></body></html> |