Add the ability to disable leader info contributor

Fixes #2085

Author: ryanjbaxter

docs/modules/ROOT/pages/leader-election.adoc

@@ -25,3 +25,29 @@ To specify the name of the configmap used for leader election use the following
 ----
 spring.cloud.kubernetes.leader.config-map-name=leader
 ----
+
+== Leader Election Info Contributor
+
+Spring Cloud Kubernetes Leader includes an `InfoContributor` which adds leader election information to
+Spring Boot's `/actuator/info` endpoint. This contributor provides information about the current leader,
+including the leader ID, role, and whether the current application instance is the leader.
+
+Example output:
+[source,json]
+----
+{
+  "leaderElection": {
+    "leaderId": "my-app-pod-1",
+    "role": "my-role",
+    "isLeader": true
+  }
+}
+----
+
+You can disable this `InfoContributor` by setting `management.info.leade.enabled`
+to `false` in `application.[properties | yaml]`:
+
+[source,properties]
+----
+management.info.leader.enabled=false
+----

spring-cloud-kubernetes-fabric8-leader/src/main/java/org/springframework/cloud/kubernetes/fabric8/leader/Fabric8LeaderAutoConfiguration.java

@@ -20,6 +20,7 @@
 
 import io.fabric8.kubernetes.client.KubernetesClient;
 
+import org.springframework.boot.actuate.autoconfigure.info.ConditionalOnEnabledInfoContributor;
 import org.springframework.boot.actuate.info.InfoContributor;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
@@ -74,6 +75,7 @@ public Candidate candidate(LeaderProperties leaderProperties) throws UnknownHost
 	 */
 	@Bean
 	@ConditionalOnClass(InfoContributor.class)
+	@ConditionalOnEnabledInfoContributor("leader")
 	public LeaderInfoContributor leaderInfoContributor(Fabric8LeadershipController fabric8LeadershipController,
 			Candidate candidate) {
 		return new LeaderInfoContributor(fabric8LeadershipController, candidate);

spring-cloud-kubernetes-fabric8-leader/src/test/java/org/springframework/cloud/kubernetes/fabric8/leader/Fabric8LeaderAutoConfigurationTests.java

@@ -26,8 +26,6 @@
 import org.springframework.http.MediaType;
 import org.springframework.test.web.reactive.server.WebTestClient;
 
-import static org.hamcrest.Matchers.containsString;
-
 @SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
 		properties = { "spring.main.cloud-platform=KUBERNETES", "spring.cloud.kubernetes.leader.autoStartup=false",
 				"management.endpoints.web.exposure.include=info", "management.endpoint.info.show-details=always",
@@ -52,8 +50,13 @@ void infoEndpointShouldContainLeaderElection() {
 			.exchange()
 			.expectStatus()
 			.isOk()
-			.expectBody(String.class)
-			.value(containsString("kubernetes"));
+			.expectBody()
+			.jsonPath("kubernetes")
+			.exists()
+			.jsonPath("leaderElection")
+			.exists()
+			.jsonPath("leaderElection.leaderId")
+			.exists();
 	}
 
 	@SpringBootConfiguration

spring-cloud-kubernetes-fabric8-leader/src/test/java/org/springframework/cloud/kubernetes/fabric8/leader/Fabric8LeaderInfoContributorDisabledTests.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright 2013-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.kubernetes.fabric8.leader;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.beans.factory.NoSuchBeanDefinitionException;
+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.kubernetes.commons.leader.LeaderInfoContributor;
+import org.springframework.context.ApplicationContext;
+
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+/**
+ * Tests that verify LeaderInfoContributor can be disabled via configuration property.
+ */
+@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+		properties = { "spring.main.cloud-platform=KUBERNETES", "spring.cloud.kubernetes.leader.autoStartup=false",
+				"management.info.leader.enabled=false" })
+class Fabric8LeaderInfoContributorDisabledTests {
+
+	@Autowired
+	private ApplicationContext context;
+
+	/**
+	 * Test that the LeaderInfoContributor bean is NOT present when
+	 * management.info.leader.enabled=false
+	 */
+	@Test
+	void leaderInfoContributorShouldNotBePresent() {
+		assertThatThrownBy(() -> context.getBean(LeaderInfoContributor.class))
+			.isInstanceOf(NoSuchBeanDefinitionException.class);
+	}
+
+	@SpringBootConfiguration
+	@EnableAutoConfiguration
+	protected static class TestConfig {
+
+	}
+
+}