b435ce3575
Also remove the bogus spring.cloud.gateway.proxy.auto-forward setting from the tests. Fixes gh-3154
81 lines
3.7 KiB
Plaintext
81 lines
3.7 KiB
Plaintext
[[proxy-exchange-gateway]]
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= Proxy Exchange Gateway with Spring MVC or Webflux
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WARNING: The following describes an alternative style gateway. None of the Spring Cloud Gateway Server documentation applies to what follows.
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== How to Include Spring Cloud Gateway Proxy Exchange
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To include Spring Cloud Gateway Proxy Exchange in your project, use the artifact with a group ID of `org.springframework.cloud` and an artifact ID of `spring-cloud-gateway-mvc` for the MVC Proxy Exchange. For the WebFlux Proxy Exchange use artifact with a group ID of `org.springframework.cloud` and an artifact ID of `spring-cloud-gateway-webflux`.
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See the https://projects.spring.io/spring-cloud/[Spring Cloud Project page] for details on setting up your build system with the current Spring Cloud Release Train.
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== Using Proxy Exchange
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Spring Cloud Gateway provides a utility object called `ProxyExchange`.
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You can use it inside a regular Spring web handler as a method parameter.
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It supports basic downstream HTTP exchanges through methods that mirror the HTTP verbs.
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With MVC, it also supports forwarding to a local handler through the `forward()` method.
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To use the `ProxyExchange`, include the right module in your classpath (either `spring-cloud-gateway-mvc` or `spring-cloud-gateway-webflux`).
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The following MVC example proxies a request to `/test` downstream to a remote server:
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[source,java]
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----
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@RestController
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@SpringBootApplication
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public class GatewaySampleApplication {
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@Value("${remote.home}")
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private URI home;
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@GetMapping("/test")
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public ResponseEntity<?> proxy(ProxyExchange<byte[]> proxy) throws Exception {
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return proxy.uri(home.toString() + "/image/png").get();
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}
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}
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----
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The following example does the same thing with Webflux:
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[source,java]
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----
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@RestController
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@SpringBootApplication
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public class GatewaySampleApplication {
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@Value("${remote.home}")
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private URI home;
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@GetMapping("/test")
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public Mono<ResponseEntity<?>> proxy(ProxyExchange<byte[]> proxy) throws Exception {
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return proxy.uri(home.toString() + "/image/png").get();
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}
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}
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----
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Convenience methods on the `ProxyExchange` enable the handler method to discover and enhance the URI path of the incoming request.
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For example, you might want to extract the trailing elements of a path to pass them downstream:
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[source,java]
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----
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@GetMapping("/proxy/path/**")
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public ResponseEntity<?> proxyPath(ProxyExchange<byte[]> proxy) throws Exception {
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String path = proxy.path("/proxy/path/");
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return proxy.uri(home.toString() + "/foos/" + path).get();
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}
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----
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All the features of Spring MVC and Webflux are available to gateway handler methods.
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As a result, you can inject request headers and query parameters, for instance, and you can constrain the incoming requests with declarations in the mapping annotation.
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See the documentation for `@RequestMapping` in Spring MVC for more details of those features.
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You can add headers to the downstream response by using the `header()` methods on `ProxyExchange`.
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You can also manipulate response headers (and anything else you like in the response) by adding a mapper to the `get()` method (and other methods).
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The mapper is a `Function` that takes the incoming `ResponseEntity` and converts it to an outgoing one.
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First-class support is provided for "`sensitive`" headers (by default, `cookie` and `authorization`) and "`skipped`" headers (by default, `content-length` and `host`), which are not passed downstream, and for "`proxy`" (`x-forwarded-*`) headers. The idea behind "`skipped`" headers is that they may result in problems when copied over to the downstream request. For example: because of the way that the `ProxyExchange` calls the downstream endpoint the content's length might have changed or even use a `Transfer-Encoding: chunked` instead of a `Content-Length` header.
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