Add Bus Trace Endpoint

docs/modules/ROOT/pages/spring-cloud-bus/configuration.adoc

@@ -24,42 +24,37 @@ NOTE: If you have enabled https://docs.spring.io/spring-cloud-config/reference/c
 [[tracing-bus-events]]
 == Tracing Bus Events
 
-Bus events (subclasses of `RemoteApplicationEvent`) can be traced by setting
-`spring.cloud.bus.trace.enabled=true`. If you do so, the Spring Boot `TraceRepository`
-(if it is present) shows each event sent and all the acks from each service instance. The
-following example comes from the `/trace` endpoint:
+Bus events (subclasses of `RemoteApplicationEvent`) can be traced by setting `spring.cloud.bus.trace.enabled=true` and `management.endpoints.web.exposure.include=bustrace`.
+When enabled, the Spring Cloud Bus `TraceRepository` (by default, an `InMemoryTraceRepository`, or you can provide your own `TraceRepository` bean) records each event sent and all acks from each service instance.
+The following example comes from the `/actuator/bustrace` endpoint:
 
 [source,json]
 ----
 {
-  "timestamp": "2015-11-26T10:24:44.411+0000",
-  "info": {
-    "signal": "spring.cloud.bus.ack",
-    "type": "RefreshRemoteApplicationEvent",
-    "id": "c4d374b7-58ea-4928-a312-31984def293b",
-    "origin": "stores:8081",
-    "destination": "*:**"
-  }
-  },
-  {
-  "timestamp": "2015-11-26T10:24:41.864+0000",
-  "info": {
-    "signal": "spring.cloud.bus.sent",
-    "type": "RefreshRemoteApplicationEvent",
-    "id": "c4d374b7-58ea-4928-a312-31984def293b",
-    "origin": "customers:9000",
-    "destination": "*:**"
-  }
-  },
-  {
-  "timestamp": "2015-11-26T10:24:41.862+0000",
-  "info": {
-    "signal": "spring.cloud.bus.ack",
-    "type": "RefreshRemoteApplicationEvent",
-    "id": "c4d374b7-58ea-4928-a312-31984def293b",
-    "origin": "customers:9000",
-    "destination": "*:**"
-  }
+  "traces": [
+    {
+      "timestamp": "2026-08-23T06:38:29.731486Z",
+      "origin": "stores:8081",
+      "signal": "spring.cloud.bus.ack",
+      "type": "RefreshRemoteApplicationEvent"
+    },
+    {
+      "timestamp": "2026-08-23T06:38:25.059455800Z",
+      "destination": "**:**",
+      "id": "2141f38c-7987-46a0-997a-ac95849365e0",
+      "origin": "customers:9000",
+      "signal": "spring.cloud.bus.sent",
+      "type": "RefreshRemoteApplicationEvent"
+    },
+    {
+      "timestamp": "2026-08-23T06:38:25.058947100Z",
+      "destination": "**",
+      "id": "2141f38c-7987-46a0-997a-ac95849365e0",
+      "origin": "customers:9000",
+      "signal": "spring.cloud.bus.ack",
+      "type": "RefreshRemoteApplicationEvent"
+    }
+  ]
 }
 ----
 

spring-cloud-bus-tests/src/test/java/org/springframework/cloud/bus/BusTraceEndpointTests.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2012-present 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.cloud.bus;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.SpringBootConfiguration;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.cloud.bus.endpoint.TraceBusEndpoint;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Test for {@link TraceBusEndpoint}.
+ *
+ * @author Ngoc Nhan
+ */
+@SpringBootTest(
+		properties = { "management.endpoints.web.exposure.include=bustrace", "spring.cloud.bus.trace.enabled=true" })
+public class BusTraceEndpointTests {
+
+	@Autowired(required = false)
+	private TraceBusEndpoint traceBusEndpoint;
+
+	@Test
+	public void contextLoads() {
+		assertThat(this.traceBusEndpoint).isNotNull();
+	}
+
+	@SpringBootConfiguration
+	@EnableAutoConfiguration
+	protected static class TestConfig {
+
+	}
+
+}

spring-cloud-bus-tests/src/test/java/org/springframework/cloud/bus/TraceListenerIntegrationTests.java

@@ -0,0 +1,80 @@
+/*
+ * Copyright 2012-present 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.cloud.bus;
+
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+import org.testcontainers.junit.jupiter.Container;
+import org.testcontainers.junit.jupiter.Testcontainers;
+import org.testcontainers.rabbitmq.RabbitMQContainer;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.SpringBootConfiguration;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.testcontainers.service.connection.ServiceConnection;
+import org.springframework.boot.webtestclient.autoconfigure.AutoConfigureWebTestClient;
+import org.springframework.cloud.bus.trace.Trace;
+import org.springframework.test.web.reactive.server.WebTestClient;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.boot.test.context.SpringBootTest.WebEnvironment.RANDOM_PORT;
+
+/**
+ * Test for {@link org.springframework.cloud.bus.endpoint.TraceBusEndpoint}.
+ *
+ * @author Ngoc Nhan
+ */
+@Testcontainers
+@SpringBootTest(webEnvironment = RANDOM_PORT,
+		properties = { "management.endpoints.web.exposure.include=busrefresh,bustrace",
+				"spring.cloud.bus.trace.enabled=true" })
+@AutoConfigureWebTestClient
+public class TraceListenerIntegrationTests {
+
+	@Container
+	@ServiceConnection
+	static RabbitMQContainer rabbitMQContainer = new RabbitMQContainer("rabbitmq:4.0-management");
+
+	@Test
+	void busTrace(@Autowired WebTestClient client) {
+
+		client.post().uri("/actuator/busrefresh").exchange().expectStatus().is2xxSuccessful();
+		BusTraceResponse response = client.get()
+			.uri("/actuator/bustrace")
+			.exchange()
+			.expectStatus()
+			.is2xxSuccessful()
+			.expectBody(BusTraceResponse.class)
+			.returnResult()
+			.getResponseBody();
+		assertThat(response).isNotNull();
+		assertThat(response.traces()).isNotEmpty().hasSize(2);
+	}
+
+	@SpringBootConfiguration
+	@EnableAutoConfiguration
+	static class TestConfig {
+
+	}
+
+	record BusTraceResponse(List<Trace> traces) {
+
+	}
+
+}

spring-cloud-bus/src/main/java/org/springframework/cloud/bus/BusAutoConfiguration.java

@@ -19,17 +19,19 @@
 import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.boot.actuate.autoconfigure.endpoint.condition.ConditionalOnAvailableEndpoint;
 import org.springframework.boot.actuate.endpoint.annotation.Endpoint;
-import org.springframework.boot.actuate.web.exchanges.HttpExchangeRepository;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.cloud.bus.endpoint.EnvironmentBusEndpoint;
+import org.springframework.cloud.bus.endpoint.TraceBusEndpoint;
 import org.springframework.cloud.bus.event.Destination;
 import org.springframework.cloud.bus.event.EnvironmentChangeListener;
 import org.springframework.cloud.bus.event.PathDestinationFactory;
 import org.springframework.cloud.bus.event.TraceListener;
+import org.springframework.cloud.bus.trace.InMemoryTraceRepository;
+import org.springframework.cloud.bus.trace.TraceRepository;
 import org.springframework.cloud.context.environment.EnvironmentManager;
 import org.springframework.context.ApplicationEventPublisher;
 import org.springframework.context.annotation.Bean;
@@ -68,14 +70,28 @@ public BusConsumer busConsumer(ApplicationEventPublisher applicationEventPublish
 
 	@Configuration(proxyBeanMethods = false)
 	@ConditionalOnClass({ Endpoint.class })
-	@ConditionalOnBean(HttpExchangeRepository.class)
 	@ConditionalOnProperty(BusProperties.PREFIX + ".trace.enabled")
+	@ConditionalOnAvailableEndpoint(TraceBusEndpoint.class)
 	protected static class BusAckTraceConfiguration {
 
 		@Bean
 		@ConditionalOnMissingBean
-		public TraceListener ackTraceListener(HttpExchangeRepository repository) {
-			return new TraceListener(repository);
+		public TraceRepository traceRepository() {
+			return new InMemoryTraceRepository();
+		}
+
+		@Bean
+		@ConditionalOnBean(TraceRepository.class)
+		@ConditionalOnMissingBean
+		public TraceBusEndpoint traceBusEndpoint(TraceRepository traceRepository) {
+			return new TraceBusEndpoint(traceRepository);
+		}
+
+		@Bean
+		@ConditionalOnBean(TraceRepository.class)
+		@ConditionalOnMissingBean
+		public TraceListener traceListener(TraceRepository traceRepository) {
+			return new TraceListener(traceRepository);
 		}
 
 	}

spring-cloud-bus/src/main/java/org/springframework/cloud/bus/endpoint/TraceBusEndpoint.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright 2012-present 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.cloud.bus.endpoint;
+
+import java.util.List;
+
+import org.springframework.boot.actuate.endpoint.OperationResponseBody;
+import org.springframework.boot.actuate.endpoint.annotation.Endpoint;
+import org.springframework.boot.actuate.endpoint.annotation.ReadOperation;
+import org.springframework.cloud.bus.trace.Trace;
+import org.springframework.cloud.bus.trace.TraceRepository;
+import org.springframework.util.Assert;
+
+/**
+ * {@link Endpoint @Endpoint} to expose {@link Trace} information.
+ *
+ * @author Ngoc Nhan
+ * @since 5.0.4
+ */
+@Endpoint(id = "bustrace")
+public class TraceBusEndpoint {
+
+	private final TraceRepository repository;
+
+	/**
+	 * Create a new {@link TraceBusEndpoint} instance.
+	 * @param repository the trace repository
+	 */
+	public TraceBusEndpoint(TraceRepository repository) {
+		Assert.notNull(repository, "'repository' must not be null");
+		this.repository = repository;
+	}
+
+	/**
+	 * Description of an application's {@link Trace} entries.
+	 */
+	@ReadOperation
+	public TraceDescriptor busTrace() {
+		return new TraceDescriptor(this.repository.findAll());
+	}
+
+	public static final class TraceDescriptor implements OperationResponseBody {
+
+		private final List<Trace> traces;
+
+		private TraceDescriptor(List<Trace> traces) {
+			this.traces = traces;
+		}
+
+		public List<Trace> getTraces() {
+			return this.traces;
+		}
+
+	}
+
+}