Only add management error page for Spring MVC

Move management `ErrorPage` registration from the
`WebMvcEndpointChildContextConfiguration` to
`WebMvcEndpointChildContextConfiguration` and only add it when the
error controller is registered.

Fixes gh-17938

Author: philwebb

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/web/server/ManagementWebServerFactoryCustomizer.java

@@ -28,7 +28,6 @@
 import org.springframework.boot.autoconfigure.web.ServerProperties;
 import org.springframework.boot.util.LambdaSafe;
 import org.springframework.boot.web.server.ConfigurableWebServerFactory;
-import org.springframework.boot.web.server.ErrorPage;
 import org.springframework.boot.web.server.Ssl;
 import org.springframework.boot.web.server.WebServerFactory;
 import org.springframework.boot.web.server.WebServerFactoryCustomizer;
@@ -107,7 +106,6 @@ protected void customize(T factory, ManagementServerProperties managementServerP
 		}
 		factory.setServerHeader(serverProperties.getServerHeader());
 		factory.setAddress(managementServerProperties.getAddress());
-		factory.addErrorPages(new ErrorPage(serverProperties.getError().getPath()));
 	}
 
 }

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/web/servlet/WebMvcEndpointChildContextConfiguration.java

@@ -24,11 +24,16 @@
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication.Type;
+import org.springframework.boot.autoconfigure.web.ServerProperties;
 import org.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfiguration;
 import org.springframework.boot.autoconfigure.web.servlet.DispatcherServletRegistrationBean;
+import org.springframework.boot.web.server.ErrorPage;
+import org.springframework.boot.web.server.WebServerFactoryCustomizer;
 import org.springframework.boot.web.servlet.error.ErrorAttributes;
 import org.springframework.boot.web.servlet.filter.OrderedRequestContextFilter;
+import org.springframework.boot.web.servlet.server.ConfigurableServletWebServerFactory;
 import org.springframework.context.annotation.Bean;
+import org.springframework.core.Ordered;
 import org.springframework.web.context.request.RequestContextListener;
 import org.springframework.web.filter.RequestContextFilter;
 import org.springframework.web.servlet.DispatcherServlet;
@@ -59,6 +64,12 @@ public ManagementErrorEndpoint errorEndpoint(ErrorAttributes errorAttributes) {
 		return new ManagementErrorEndpoint(errorAttributes);
 	}
 
+	@Bean
+	@ConditionalOnBean(ErrorAttributes.class)
+	public ManagementErrorPageCustomizer managementErrorPageCustomizer(ServerProperties serverProperties) {
+		return new ManagementErrorPageCustomizer(serverProperties);
+	}
+
 	@Bean(name = DispatcherServletAutoConfiguration.DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)
 	public DispatcherServlet dispatcherServlet() {
 		DispatcherServlet dispatcherServlet = new DispatcherServlet();
@@ -96,4 +107,29 @@ public RequestContextFilter requestContextFilter() {
 		return new OrderedRequestContextFilter();
 	}
 
+	/**
+	 * {@link WebServerFactoryCustomizer} to add an {@link ErrorPage} so that the
+	 * {@link ManagementErrorEndpoint} can be used.
+	 */
+	private static class ManagementErrorPageCustomizer
+			implements WebServerFactoryCustomizer<ConfigurableServletWebServerFactory>, Ordered {
+
+		private final ServerProperties properties;
+
+		ManagementErrorPageCustomizer(ServerProperties properties) {
+			this.properties = properties;
+		}
+
+		@Override
+		public void customize(ConfigurableServletWebServerFactory factory) {
+			factory.addErrorPages(new ErrorPage(this.properties.getError().getPath()));
+		}
+
+		@Override
+		public int getOrder() {
+			return 0;
+		}
+
+	}
+
 }

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/web/servlet/WebMvcEndpointChildContextConfigurationIntegrationTests.java

@@ -0,0 +1,77 @@
+/*
+ * Copyright 2012-2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.actuate.autoconfigure.web.servlet;
+
+import org.junit.Test;
+
+import org.springframework.boot.actuate.autoconfigure.endpoint.EndpointAutoConfiguration;
+import org.springframework.boot.actuate.autoconfigure.endpoint.web.WebEndpointAutoConfiguration;
+import org.springframework.boot.actuate.autoconfigure.web.server.ManagementContextAutoConfiguration;
+import org.springframework.boot.actuate.endpoint.annotation.Endpoint;
+import org.springframework.boot.actuate.endpoint.annotation.ReadOperation;
+import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfiguration;
+import org.springframework.boot.autoconfigure.web.servlet.ServletWebServerFactoryAutoConfiguration;
+import org.springframework.boot.autoconfigure.web.servlet.error.ErrorMvcAutoConfiguration;
+import org.springframework.boot.test.context.runner.WebApplicationContextRunner;
+import org.springframework.boot.web.context.ServerPortInfoApplicationContextInitializer;
+import org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext;
+import org.springframework.http.MediaType;
+import org.springframework.stereotype.Component;
+import org.springframework.web.reactive.function.client.ClientResponse;
+import org.springframework.web.reactive.function.client.WebClient;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Integration tests for {@link WebMvcEndpointChildContextConfiguration}.
+ *
+ * @author Phillip Webb
+ */
+public class WebMvcEndpointChildContextConfigurationIntegrationTests {
+
+	@Test // gh-17938
+	public void errorPageAndErrorControllerAreUsed() {
+		new WebApplicationContextRunner(AnnotationConfigServletWebServerApplicationContext::new)
+				.withConfiguration(AutoConfigurations.of(ManagementContextAutoConfiguration.class,
+						ServletWebServerFactoryAutoConfiguration.class, ServletManagementContextAutoConfiguration.class,
+						WebEndpointAutoConfiguration.class, EndpointAutoConfiguration.class,
+						DispatcherServletAutoConfiguration.class, ErrorMvcAutoConfiguration.class))
+				.withUserConfiguration(FailingEndpoint.class)
+				.withInitializer(new ServerPortInfoApplicationContextInitializer()).withPropertyValues("server.port=0",
+						"management.server.port=0", "management.endpoints.web.exposure.include=*")
+				.run((context) -> {
+					String port = context.getEnvironment().getProperty("local.management.port");
+					WebClient client = WebClient.create("http://localhost:" + port);
+					ClientResponse response = client.get().uri("actuator/fail").accept(MediaType.APPLICATION_JSON)
+							.exchange().block();
+					assertThat(response.bodyToMono(String.class).block()).contains("message\":\"Epic Fail");
+				});
+	}
+
+	@Component
+	@Endpoint(id = "fail")
+	public static class FailingEndpoint {
+
+		@ReadOperation
+		public String fail() {
+			throw new IllegalStateException("Epic Fail");
+		}
+
+	}
+
+}