Updates RetryFilterFunctions to support HttpMethods

Author: spencergibb

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/filter/RetryFilterFunctions.java

@@ -26,6 +26,8 @@
 import java.util.concurrent.TimeoutException;
 import java.util.function.Consumer;
 
+import org.springframework.core.NestedRuntimeException;
+import org.springframework.http.HttpMethod;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.HttpStatusCode;
 import org.springframework.retry.RetryContext;
@@ -35,8 +37,8 @@
 import org.springframework.retry.policy.SimpleRetryPolicy;
 import org.springframework.retry.support.RetryTemplate;
 import org.springframework.retry.support.RetryTemplateBuilder;
-import org.springframework.web.client.HttpServerErrorException;
 import org.springframework.web.servlet.function.HandlerFilterFunction;
+import org.springframework.web.servlet.function.ServerRequest;
 import org.springframework.web.servlet.function.ServerResponse;
 
 public abstract class RetryFilterFunctions {
@@ -56,14 +58,16 @@ public static HandlerFilterFunction<ServerResponse, ServerResponse> retry(Consum
 		Map<Class<? extends Throwable>, Boolean> retryableExceptions = new HashMap<>();
 		config.getExceptions().forEach(exception -> retryableExceptions.put(exception, true));
 		SimpleRetryPolicy simpleRetryPolicy = new SimpleRetryPolicy(config.getRetries(), retryableExceptions);
-		compositeRetryPolicy.setPolicies(
-				Arrays.asList(simpleRetryPolicy, new HttpStatusRetryPolicy(config)).toArray(new RetryPolicy[0]));
+		compositeRetryPolicy
+				.setPolicies(Arrays.asList(simpleRetryPolicy, new HttpRetryPolicy(config)).toArray(new RetryPolicy[0]));
 		RetryTemplate retryTemplate = retryTemplateBuilder.customPolicy(compositeRetryPolicy).build();
 		return (request, next) -> retryTemplate.execute(context -> {
 			ServerResponse serverResponse = next.handle(request);
 
-			if (isRetryableStatusCode(serverResponse.statusCode(), config)) {
-				throw new HttpServerErrorException(serverResponse.statusCode());
+			if (isRetryableStatusCode(serverResponse.statusCode(), config)
+					&& isRetryableMethod(request.method(), config)) {
+				// use this to transfer information to HttpStatusRetryPolicy
+				throw new RetryException(request, serverResponse);
 			}
 			return serverResponse;
 		});
@@ -73,19 +77,24 @@ private static boolean isRetryableStatusCode(HttpStatusCode httpStatus, RetryCon
 		return config.getSeries().stream().anyMatch(series -> HttpStatus.Series.resolve(httpStatus.value()) == series);
 	}
 
-	public static class HttpStatusRetryPolicy extends NeverRetryPolicy {
+	private static boolean isRetryableMethod(HttpMethod method, RetryConfig config) {
+		return config.methods.contains(method);
+	}
+
+	public static class HttpRetryPolicy extends NeverRetryPolicy {
 
 		private final RetryConfig config;
 
-		public HttpStatusRetryPolicy(RetryConfig config) {
+		public HttpRetryPolicy(RetryConfig config) {
 			this.config = config;
 		}
 
 		@Override
 		public boolean canRetry(RetryContext context) {
 			// TODO: custom exception
-			if (context.getLastThrowable() instanceof HttpServerErrorException e) {
-				return isRetryableStatusCode(e.getStatusCode(), config);
+			if (context.getLastThrowable() instanceof RetryException e) {
+				return isRetryableStatusCode(e.getResponse().statusCode(), config)
+						&& isRetryableMethod(e.getRequest().method(), config);
 			}
 			return super.canRetry(context);
 		}
@@ -99,9 +108,12 @@ public static class RetryConfig {
 		private Set<HttpStatus.Series> series = new HashSet<>(List.of(HttpStatus.Series.SERVER_ERROR));
 
 		private Set<Class<? extends Throwable>> exceptions = new HashSet<>(
-				List.of(IOException.class, TimeoutException.class, HttpServerErrorException.class));
+				List.of(IOException.class, TimeoutException.class, RetryException.class));
+
+		private Set<HttpMethod> methods = new HashSet<>(List.of(HttpMethod.GET));
 
 		// TODO: individual statuses
+		// TODO: backoff
 		// TODO: support more Spring Retry policies
 
 		public int getRetries() {
@@ -141,6 +153,42 @@ public RetryConfig addExceptions(Class<? extends Throwable>... exceptions) {
 			return this;
 		}
 
+		public Set<HttpMethod> getMethods() {
+			return methods;
+		}
+
+		public RetryConfig setMethods(Set<HttpMethod> methods) {
+			this.methods = methods;
+			return this;
+		}
+
+		public RetryConfig addMethods(HttpMethod... methods) {
+			this.methods.addAll(Arrays.asList(methods));
+			return this;
+		}
+
+	}
+
+	private static class RetryException extends NestedRuntimeException {
+
+		private final ServerRequest request;
+
+		private final ServerResponse response;
+
+		RetryException(ServerRequest request, ServerResponse response) {
+			super(null);
+			this.request = request;
+			this.response = response;
+		}
+
+		public ServerRequest getRequest() {
+			return request;
+		}
+
+		public ServerResponse getResponse() {
+			return response;
+		}
+
 	}
 
 }

spring-cloud-gateway-server-mvc/src/test/java/org/springframework/cloud/gateway/server/mvc/ServerMvcIntegrationTests.java

@@ -802,6 +802,7 @@ public RouterFunction<ServerResponse> gatewayRouterFunctionsRetry() {
 					.route(path("/retry"), http())
 					.before(new LocalServerPortUriResolver())
 					.filter(retry(3))
+					//.filter(retry(config -> config.setRetries(3).setSeries(Set.of(HttpStatus.Series.SERVER_ERROR)).setMethods(Set.of(HttpMethod.GET, HttpMethod.POST))))
 					.filter(prefixPath("/do"))
 					.build();
 			// @formatter:on