Support loadbalancer lifecycle (#2066)

* Add LoadBalancer lifecycle callbacks.

* Switch test to junit jupiter.

* Add more tests.

* Update docs.

* Adjust to changes in commons.

docs/src/main/asciidoc/spring-cloud-gateway.adoc

@@ -1803,9 +1803,7 @@ However, if `GATEWAY_SCHEME_PREFIX_ATTR` is specified for the
 route in the Gateway configuration, the prefix is stripped and the resulting scheme from the
 route URL overrides the `ServiceInstance` configuration.
 
-WARNING: `LoadBalancerClientFilter` uses a blocking ribbon `LoadBalancerClient` under the hood.
-We suggest you use <<reactive-loadbalancer-client-filter,`ReactiveLoadBalancerClientFilter` instead>>.
-You can switch to it by setting the value of the `spring.cloud.loadbalancer.ribbon.enabled` to `false`.
+TIP: Gateway supports all the LoadBalancer features. You can read more about them in the https://docs.spring.io/spring-cloud-commons/docs/current/reference/html/#spring-cloud-loadbalancer[Spring Cloud Commons documentation].
 
 [[reactive-loadbalancer-client-filter]]
 === The `ReactiveLoadBalancerClientFilter`

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

@@ -18,16 +18,21 @@ package org.springframework.cloud.gateway.filter;
 
 import java.net.URI;
 import java.util.Map;
+import java.util.Set;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import reactor.core.publisher.Mono;
 
 import org.springframework.cloud.client.ServiceInstance;
+import org.springframework.cloud.client.loadbalancer.CompletionContext;
 import org.springframework.cloud.client.loadbalancer.DefaultRequest;
+import org.springframework.cloud.client.loadbalancer.LoadBalancerLifecycle;
+import org.springframework.cloud.client.loadbalancer.LoadBalancerLifecycleValidator;
 import org.springframework.cloud.client.loadbalancer.LoadBalancerUriTools;
+import org.springframework.cloud.client.loadbalancer.RequestData;
+import org.springframework.cloud.client.loadbalancer.RequestDataContext;
 import org.springframework.cloud.client.loadbalancer.Response;
-import org.springframework.cloud.client.loadbalancer.ServerHttpRequestContext;
 import org.springframework.cloud.client.loadbalancer.reactive.LoadBalancerProperties;
 import org.springframework.cloud.gateway.config.GatewayLoadBalancerProperties;
 import org.springframework.cloud.gateway.support.DelegatingServiceInstance;
@@ -36,8 +41,12 @@ import org.springframework.cloud.loadbalancer.core.ReactorLoadBalancer;
 import org.springframework.cloud.loadbalancer.core.ReactorServiceInstanceLoadBalancer;
 import org.springframework.cloud.loadbalancer.support.LoadBalancerClientFactory;
 import org.springframework.core.Ordered;
+import org.springframework.http.server.reactive.ServerHttpRequest;
+import org.springframework.http.server.reactive.ServerHttpResponse;
+import org.springframework.web.reactive.function.client.ClientResponse;
 import org.springframework.web.server.ServerWebExchange;
 
+import static org.springframework.cloud.gateway.support.ServerWebExchangeUtils.GATEWAY_LOADBALANCER_RESPONSE_ATTR;
 import static org.springframework.cloud.gateway.support.ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR;
 import static org.springframework.cloud.gateway.support.ServerWebExchangeUtils.GATEWAY_SCHEME_PREFIX_ATTR;
 import static org.springframework.cloud.gateway.support.ServerWebExchangeUtils.addOriginalRequestUrl;
@@ -50,7 +59,7 @@ import static org.springframework.cloud.gateway.support.ServerWebExchangeUtils.a
  * @author Tim Ysewyn
  * @author Olga Maciaszek-Sharma
  */
-@SuppressWarnings("rawtypes")
+@SuppressWarnings({ "rawtypes", "unchecked" })
 public class ReactiveLoadBalancerClientFilter implements GlobalFilter, Ordered {
 
 	private static final Log log = LogFactory.getLog(ReactiveLoadBalancerClientFilter.class);
@@ -79,7 +88,6 @@ public class ReactiveLoadBalancerClientFilter implements GlobalFilter, Ordered {
 	}
 
 	@Override
-	@SuppressWarnings("Duplicates")
 	public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
 		URI url = exchange.getAttribute(GATEWAY_REQUEST_URL_ATTR);
 		String schemePrefix = exchange.getAttribute(GATEWAY_SCHEME_PREFIX_ATTR);
@@ -93,9 +101,16 @@ public class ReactiveLoadBalancerClientFilter implements GlobalFilter, Ordered {
 			log.trace(ReactiveLoadBalancerClientFilter.class.getSimpleName() + " url before: " + url);
 		}
 
-		return choose(exchange).doOnNext(response -> {
+		URI requestUri = exchange.getAttribute(GATEWAY_REQUEST_URL_ATTR);
+		String serviceId = requestUri.getHost();
+		Set<LoadBalancerLifecycle> supportedLifecycleProcessors = LoadBalancerLifecycleValidator
+				.getSupportedLifecycleProcessors(clientFactory.getInstances(serviceId, LoadBalancerLifecycle.class),
+						ServerHttpRequest.class, ServerHttpResponse.class, ServiceInstance.class);
+		return choose(exchange, serviceId, supportedLifecycleProcessors).doOnNext(response -> {
 
 			if (!response.hasServer()) {
+				supportedLifecycleProcessors.forEach(lifecycle -> lifecycle
+						.onComplete(new CompletionContext<>(CompletionContext.Status.DISCARD, response)));
 				throw NotFoundException.create(properties.isUse404(), "Unable to find instance for " + url.getHost());
 			}
 
@@ -119,23 +134,30 @@ public class ReactiveLoadBalancerClientFilter implements GlobalFilter, Ordered {
 				log.trace("LoadBalancerClientFilter url chosen: " + requestUrl);
 			}
 			exchange.getAttributes().put(GATEWAY_REQUEST_URL_ATTR, requestUrl);
-		}).then(chain.filter(exchange));
+			exchange.getAttributes().put(GATEWAY_LOADBALANCER_RESPONSE_ATTR, response);
+		}).then(chain.filter(exchange))
+				.doOnError(throwable -> supportedLifecycleProcessors.forEach(lifecycle -> lifecycle.onComplete(
+						new CompletionContext<ClientResponse, ServiceInstance>(CompletionContext.Status.FAILED,
+								throwable, exchange.getAttribute(GATEWAY_LOADBALANCER_RESPONSE_ATTR)))))
+				.doOnSuccess(aVoid -> supportedLifecycleProcessors.forEach(
+						lifecycle -> lifecycle.onComplete(new CompletionContext<>(CompletionContext.Status.SUCCESS,
+								exchange.getAttribute(GATEWAY_LOADBALANCER_RESPONSE_ATTR), exchange.getResponse()))));
 	}
 
 	protected URI reconstructURI(ServiceInstance serviceInstance, URI original) {
 		return LoadBalancerUriTools.reconstructURI(serviceInstance, original);
 	}
 
-	private Mono<Response<ServiceInstance>> choose(ServerWebExchange exchange) {
-		URI uri = exchange.getAttribute(GATEWAY_REQUEST_URL_ATTR);
-		String serviceId = uri.getHost();
+	private Mono<Response<ServiceInstance>> choose(ServerWebExchange exchange, String serviceId,
+			Set<LoadBalancerLifecycle> supportedLifecycleProcessors) {
 		ReactorLoadBalancer<ServiceInstance> loadBalancer = this.clientFactory.getInstance(serviceId,
 				ReactorServiceInstanceLoadBalancer.class);
 		if (loadBalancer == null) {
 			throw new NotFoundException("No loadbalancer available for " + serviceId);
 		}
-		DefaultRequest<ServerHttpRequestContext> lbRequest = new DefaultRequest<>(new ServerHttpRequestContext(
-				exchange.getRequest(), getHint(serviceId, loadBalancerProperties.getHint())));
+		DefaultRequest<RequestDataContext> lbRequest = new DefaultRequest<>(new RequestDataContext(
+				new RequestData(exchange.getRequest()), getHint(serviceId, loadBalancerProperties.getHint())));
+		supportedLifecycleProcessors.forEach(lifecycle -> lifecycle.onStart(lbRequest));
 		return loadBalancer.choose(lbRequest);
 	}
 

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/support/ServerWebExchangeUtils.java

@@ -31,6 +31,7 @@ import org.apache.commons.logging.LogFactory;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
+import org.springframework.cloud.client.loadbalancer.Response;
 import org.springframework.cloud.gateway.filter.factory.GatewayFilterFactory;
 import org.springframework.cloud.gateway.handler.AsyncPredicate;
 import org.springframework.cloud.gateway.handler.predicate.RoutePredicateFactory;
@@ -148,6 +149,11 @@ public final class ServerWebExchangeUtils {
 	 */
 	public static final String CACHED_REQUEST_BODY_ATTR = "cachedRequestBody";
 
+	/**
+	 * Gateway LoadBalancer {@link Response} attribute name.
+	 */
+	public static final String GATEWAY_LOADBALANCER_RESPONSE_ATTR = qualify("gatewayLoadBalancerResponse");
+
 	private ServerWebExchangeUtils() {
 		throw new AssertionError("Must not instantiate utility class.");
 	}
@@ -194,7 +200,7 @@ public final class ServerWebExchangeUtils {
 			return setResponseStatus(exchange, statusHolder.getHttpStatus());
 		}
 		if (statusHolder.getStatus() != null && exchange.getResponse() instanceof AbstractServerHttpResponse) { // non-standard
-			((AbstractServerHttpResponse) exchange.getResponse()).setStatusCodeValue(statusHolder.getStatus());
+			((AbstractServerHttpResponse) exchange.getResponse()).setRawStatusCode(statusHolder.getStatus());
 			return true;
 		}
 		return false;
@@ -210,9 +216,9 @@ public final class ServerWebExchangeUtils {
 				UriComponentsBuilder.fromUri(uri).build(true);
 				return true;
 			}
-			catch (IllegalArgumentException ignore) {
+			catch (IllegalArgumentException ignored) {
 				if (log.isTraceEnabled()) {
-					log.trace("Error in containsEncodedParts", ignore);
+					log.trace("Error in containsEncodedParts", ignored);
 				}
 			}
 

spring-cloud-gateway-server/src/test/java/org/springframework/cloud/gateway/filter/ReactiveLoadBalancerClientFilterTests.java

@@ -22,20 +22,24 @@ import java.util.LinkedHashSet;
 import java.util.Map;
 
 import org.jetbrains.annotations.NotNull;
-import org.junit.Before;
-import org.junit.Test;
-import org.junit.runner.RunWith;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
 import org.mockito.ArgumentCaptor;
 import org.mockito.InjectMocks;
 import org.mockito.Mock;
-import org.mockito.junit.MockitoJUnitRunner;
+import org.mockito.junit.jupiter.MockitoExtension;
 import reactor.core.publisher.Mono;
 
 import org.springframework.cloud.client.DefaultServiceInstance;
 import org.springframework.cloud.client.ServiceInstance;
+import org.springframework.cloud.client.loadbalancer.CompletionContext;
 import org.springframework.cloud.client.loadbalancer.DefaultResponse;
+import org.springframework.cloud.client.loadbalancer.EmptyResponse;
+import org.springframework.cloud.client.loadbalancer.LoadBalancerLifecycle;
 import org.springframework.cloud.client.loadbalancer.Request;
-import org.springframework.cloud.client.loadbalancer.ServerHttpRequestContext;
+import org.springframework.cloud.client.loadbalancer.RequestDataContext;
+import org.springframework.cloud.client.loadbalancer.Response;
 import org.springframework.cloud.client.loadbalancer.reactive.LoadBalancerProperties;
 import org.springframework.cloud.gateway.config.GatewayLoadBalancerProperties;
 import org.springframework.cloud.gateway.support.NotFoundException;
@@ -51,6 +55,7 @@ import org.springframework.web.server.ServerWebExchange;
 import org.springframework.web.util.UriComponentsBuilder;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.argThat;
 import static org.mockito.Mockito.mock;
@@ -58,6 +63,7 @@ import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.verifyNoInteractions;
 import static org.mockito.Mockito.verifyNoMoreInteractions;
 import static org.mockito.Mockito.when;
+import static org.springframework.cloud.gateway.support.ServerWebExchangeUtils.GATEWAY_LOADBALANCER_RESPONSE_ATTR;
 import static org.springframework.cloud.gateway.support.ServerWebExchangeUtils.GATEWAY_ORIGINAL_REQUEST_URL_ATTR;
 import static org.springframework.cloud.gateway.support.ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR;
 import static org.springframework.cloud.gateway.support.ServerWebExchangeUtils.GATEWAY_SCHEME_PREFIX_ATTR;
@@ -70,8 +76,8 @@ import static org.springframework.cloud.gateway.support.ServerWebExchangeUtils.G
  * @author Olga Maciaszek-Sharma
  */
 @SuppressWarnings("UnassignedFluxMonoInstance")
-@RunWith(MockitoJUnitRunner.class)
-public class ReactiveLoadBalancerClientFilterTests {
+@ExtendWith(MockitoExtension.class)
+class ReactiveLoadBalancerClientFilterTests {
 
 	private ServerWebExchange exchange;
 
@@ -89,14 +95,14 @@ public class ReactiveLoadBalancerClientFilterTests {
 	@InjectMocks
 	private ReactiveLoadBalancerClientFilter filter;
 
-	@Before
-	public void setup() {
+	@BeforeEach
+	void setup() {
 		properties = new GatewayLoadBalancerProperties();
 		exchange = MockServerWebExchange.from(MockServerHttpRequest.get("/mypath").build());
 	}
 
 	@Test
-	public void shouldNotFilterWhenGatewayRequestUrlIsMissing() {
+	void shouldNotFilterWhenGatewayRequestUrlIsMissing() {
 		filter.filter(exchange, chain);
 
 		verify(chain).filter(exchange);
@@ -105,7 +111,7 @@ public class ReactiveLoadBalancerClientFilterTests {
 	}
 
 	@Test
-	public void shouldNotFilterWhenGatewayRequestUrlSchemeIsNotLb() {
+	void shouldNotFilterWhenGatewayRequestUrlSchemeIsNotLb() {
 		URI uri = UriComponentsBuilder.fromUriString("http://myservice").build().toUri();
 		exchange.getAttributes().put(GATEWAY_REQUEST_URL_ATTR, uri);
 
@@ -116,17 +122,19 @@ public class ReactiveLoadBalancerClientFilterTests {
 		verifyNoInteractions(clientFactory);
 	}
 
-	@Test(expected = NotFoundException.class)
-	public void shouldThrowExceptionWhenNoServiceInstanceIsFound() {
-		URI uri = UriComponentsBuilder.fromUriString("lb://myservice").build().toUri();
-		exchange.getAttributes().put(GATEWAY_REQUEST_URL_ATTR, uri);
+	@Test
+	void shouldThrowExceptionWhenNoServiceInstanceIsFound() {
+		assertThatExceptionOfType(NotFoundException.class).isThrownBy(() -> {
+			URI uri = UriComponentsBuilder.fromUriString("lb://myservice").build().toUri();
+			exchange.getAttributes().put(GATEWAY_REQUEST_URL_ATTR, uri);
 
-		filter.filter(exchange, chain).block();
+			filter.filter(exchange, chain).block();
+		});
 	}
 
 	@SuppressWarnings("unchecked")
 	@Test
-	public void shouldFilter() {
+	void shouldFilter() {
 		URI url = UriComponentsBuilder.fromUriString("lb://myservice").build().toUri();
 		exchange.getAttributes().put(GATEWAY_REQUEST_URL_ATTR, url);
 
@@ -145,6 +153,8 @@ public class ReactiveLoadBalancerClientFilterTests {
 
 		verify(clientFactory).getInstance("myservice", ReactorServiceInstanceLoadBalancer.class);
 
+		verify(clientFactory).getInstances("myservice", LoadBalancerLifecycle.class);
+
 		verifyNoMoreInteractions(clientFactory);
 
 		assertThat((URI) exchange.getAttribute(GATEWAY_REQUEST_URL_ATTR))
@@ -155,7 +165,7 @@ public class ReactiveLoadBalancerClientFilterTests {
 	}
 
 	@Test
-	public void happyPath() {
+	void happyPath() {
 		MockServerHttpRequest request = MockServerHttpRequest.get("http://localhost/get?a=b").build();
 
 		URI lbUri = URI.create("lb://service1?a=b");
@@ -165,7 +175,7 @@ public class ReactiveLoadBalancerClientFilterTests {
 	}
 
 	@Test
-	public void noQueryParams() {
+	void noQueryParams() {
 		MockServerHttpRequest request = MockServerHttpRequest.get("http://localhost/get").build();
 
 		ServerWebExchange webExchange = testFilter(request, URI.create("lb://service1"));
@@ -174,7 +184,7 @@ public class ReactiveLoadBalancerClientFilterTests {
 	}
 
 	@Test
-	public void encodedParameters() {
+	void encodedParameters() {
 		URI url = UriComponentsBuilder.fromUriString("http://localhost/get?a=b&c=d[]").buildAndExpand().encode()
 				.toUri();
 
@@ -196,7 +206,7 @@ public class ReactiveLoadBalancerClientFilterTests {
 	}
 
 	@Test
-	public void unencodedParameters() {
+	void unencodedParameters() {
 		URI url = URI.create("http://localhost/get?a=b&c=d[]");
 
 		MockServerHttpRequest request = MockServerHttpRequest.method(HttpMethod.GET, url).build();
@@ -216,7 +226,7 @@ public class ReactiveLoadBalancerClientFilterTests {
 	}
 
 	@Test
-	public void happyPathWithAttributeRatherThanScheme() {
+	void happyPathWithAttributeRatherThanScheme() {
 		MockServerHttpRequest request = MockServerHttpRequest.get("ws://localhost/get?a=b").build();
 
 		URI lbUri = URI.create("ws://service1?a=b");
@@ -230,7 +240,7 @@ public class ReactiveLoadBalancerClientFilterTests {
 	}
 
 	@Test
-	public void shouldNotFilterWhenGatewaySchemePrefixAttrIsNotLb() {
+	void shouldNotFilterWhenGatewaySchemePrefixAttrIsNotLb() {
 		URI uri = UriComponentsBuilder.fromUriString("http://myservice").build().toUri();
 		exchange.getAttributes().put(GATEWAY_REQUEST_URL_ATTR, uri);
 		exchange.getAttributes().put(GATEWAY_SCHEME_PREFIX_ATTR, "xx");
@@ -243,7 +253,7 @@ public class ReactiveLoadBalancerClientFilterTests {
 	}
 
 	@Test
-	public void shouldThrow4O4ExceptionWhenNoServiceInstanceIsFound() {
+	void shouldThrow4O4ExceptionWhenNoServiceInstanceIsFound() {
 		URI uri = UriComponentsBuilder.fromUriString("lb://service1").build().toUri();
 		exchange.getAttributes().put(GATEWAY_REQUEST_URL_ATTR, uri);
 		RoundRobinLoadBalancer loadBalancer = new RoundRobinLoadBalancer(
@@ -263,7 +273,7 @@ public class ReactiveLoadBalancerClientFilterTests {
 
 	@SuppressWarnings("unchecked")
 	@Test
-	public void shouldOverrideSchemeUsingIsSecure() {
+	void shouldOverrideSchemeUsingIsSecure() {
 		URI url = UriComponentsBuilder.fromUriString("lb://myservice").build().toUri();
 		ServerWebExchange exchange = MockServerWebExchange
 				.from(MockServerHttpRequest.get("https://localhost:9999/mypath").build());
@@ -286,7 +296,7 @@ public class ReactiveLoadBalancerClientFilterTests {
 
 	@SuppressWarnings({ "rawtypes" })
 	@Test
-	public void shouldPassRequestToLoadBalancer() {
+	void shouldPassRequestToLoadBalancer() {
 		String hint = "test";
 		when(loadBalancerProperties.getHint()).thenReturn(buildHints(hint));
 		MockServerHttpRequest request = MockServerHttpRequest.get("http://localhost/get?a=b").build();
@@ -298,17 +308,92 @@ public class ReactiveLoadBalancerClientFilterTests {
 		when(serverWebExchange.getRequest()).thenReturn(request);
 		RoundRobinLoadBalancer loadBalancer = mock(RoundRobinLoadBalancer.class);
 		when(loadBalancer.choose(any(Request.class))).thenReturn(Mono.just(
-				new DefaultResponse(new DefaultServiceInstance("myservice1", "myservice", "localhost", 8080, false))));
+				new DefaultResponse(new DefaultServiceInstance("myservice1", "service1", "localhost", 8080, false))));
 		when(clientFactory.getInstance("service1", ReactorServiceInstanceLoadBalancer.class)).thenReturn(loadBalancer);
 		when(chain.filter(any())).thenReturn(Mono.empty());
 
 		filter.filter(serverWebExchange, chain);
 
-		verify(loadBalancer)
-				.choose(argThat((Request passedRequest) -> ((ServerHttpRequestContext) passedRequest.getContext())
-						.getClientRequest().equals(request)
-						&& ((ServerHttpRequestContext) passedRequest.getContext()).getHint().equals(hint)));
+		verify(loadBalancer).choose(argThat((Request passedRequest) -> ((RequestDataContext) passedRequest.getContext())
+				.getClientRequest().getUrl().equals(request.getURI())
+				&& ((RequestDataContext) passedRequest.getContext()).getHint().equals(hint)));
+
+	}
+
+	@SuppressWarnings({ "unchecked", "rawtypes" })
+	@Test
+	void loadBalancerLifecycleCallbacksExecutedForSuccess() {
+		LoadBalancerLifecycle lifecycleProcessor = mock(LoadBalancerLifecycle.class);
+		ServiceInstance serviceInstance = new DefaultServiceInstance("myservice1", "myservice", "localhost", 8080,
+				false);
+		ServerWebExchange serverWebExchange = mockExchange(serviceInstance, lifecycleProcessor, false);
+
+		filter.filter(serverWebExchange, chain).subscribe();
+
+		verify(lifecycleProcessor).onStart(any(Request.class));
+		verify(lifecycleProcessor).onComplete(
+				argThat(completionContext -> CompletionContext.Status.SUCCESS.equals(completionContext.status())
+						&& completionContext.getLoadBalancerResponse().getServer().equals(serviceInstance)));
+	}
+
+	@SuppressWarnings({ "unchecked", "rawtypes" })
+	@Test
+	void loadBalancerLifecycleCallbacksExecutedForDiscard() {
+		LoadBalancerLifecycle lifecycleProcessor = mock(LoadBalancerLifecycle.class);
+		ServiceInstance serviceInstance = null;
+		ServerWebExchange serverWebExchange = mockExchange(serviceInstance, lifecycleProcessor, false);
+
+		filter.filter(serverWebExchange, chain).subscribe();
+
+		verify(lifecycleProcessor).onStart(any(Request.class));
+		verify(lifecycleProcessor).onComplete(
+				argThat(completionContext -> CompletionContext.Status.DISCARD.equals(completionContext.status())));
+	}
+
+	@SuppressWarnings({ "unchecked", "rawtypes" })
+	@Test
+	void loadBalancerLifecycleCallbacksExecutedForFailed() {
+		LoadBalancerLifecycle lifecycleProcessor = mock(LoadBalancerLifecycle.class);
+		ServiceInstance serviceInstance = null;
+		ServerWebExchange serverWebExchange = mockExchange(serviceInstance, lifecycleProcessor, true);
+
+		filter.filter(serverWebExchange, chain).subscribe();
+
+		verify(lifecycleProcessor).onStart(any(Request.class));
+		verify(lifecycleProcessor).onComplete(
+				argThat(completionContext -> CompletionContext.Status.FAILED.equals(completionContext.status())));
+	}
 
+	@SuppressWarnings({ "rawtypes", "unchecked" })
+	private ServerWebExchange mockExchange(ServiceInstance serviceInstance, LoadBalancerLifecycle lifecycleProcessor,
+			boolean shouldThrowException) {
+		Response response;
+		when(lifecycleProcessor.supports(any(Class.class), any(Class.class), any(Class.class))).thenReturn(true);
+		MockServerHttpRequest request = MockServerHttpRequest.get("http://localhost/get?a=b").build();
+		URI lbUri = URI.create("lb://service1?a=b");
+		ServerWebExchange serverWebExchange = MockServerWebExchange.from(request);
+		if (serviceInstance == null) {
+			response = new EmptyResponse();
+		}
+		else {
+			response = new DefaultResponse(serviceInstance);
+		}
+		serverWebExchange.getAttributes().put(GATEWAY_REQUEST_URL_ATTR, lbUri);
+		serverWebExchange.getAttributes().put(GATEWAY_ORIGINAL_REQUEST_URL_ATTR, new LinkedHashSet<>());
+		serverWebExchange.getAttributes().put(GATEWAY_LOADBALANCER_RESPONSE_ATTR, response);
+		RoundRobinLoadBalancer loadBalancer = mock(RoundRobinLoadBalancer.class);
+		when(loadBalancer.choose(any(Request.class))).thenReturn(Mono.just(response));
+		when(clientFactory.getInstance("service1", ReactorServiceInstanceLoadBalancer.class)).thenReturn(loadBalancer);
+		Map<String, LoadBalancerLifecycle> lifecycleProcessors = new HashMap<>();
+		lifecycleProcessors.put("service1", lifecycleProcessor);
+		when(clientFactory.getInstances("service1", LoadBalancerLifecycle.class)).thenReturn(lifecycleProcessors);
+		if (shouldThrowException) {
+			when(chain.filter(any())).thenReturn(Mono.error(new UnsupportedOperationException()));
+		}
+		else {
+			when(chain.filter(any())).thenReturn(Mono.empty());
+		}
+		return serverWebExchange;
 	}
 
 	@NotNull