Add possibility to disable configmap creation (#1081)

docs/src/main/asciidoc/_configprops.adoc

@@ -86,6 +86,7 @@
 |spring.cloud.kubernetes.leader.publish-failed-events | `+++false+++` | Enable/disable publishing events in case leadership acquisition fails. Default: false
 |spring.cloud.kubernetes.leader.role |  | Role for which leadership this candidate will compete.
 |spring.cloud.kubernetes.leader.update-period | `+++60000ms+++` | Leadership status check period. Default: 60s
+|spring.cloud.kubernetes.leader.create-config-map | `+++true+++` | Enable/disable creating ConfigMap if it does not exist. Default: true
 |spring.cloud.kubernetes.loadbalancer.cluster-domain | `+++cluster.local+++` | cluster domain.
 |spring.cloud.kubernetes.loadbalancer.enabled | `+++true+++` | Load balancer enabled,default true.
 |spring.cloud.kubernetes.loadbalancer.mode |  | {@link KubernetesLoadBalancerMode} setting load balancer server list with ip of pod or service name. default value is POD.
@@ -115,4 +116,4 @@
 |spring.cloud.kubernetes.secrets.sources |  | 
 |spring.cloud.kubernetes.secrets.use-name-as-prefix | `+++false+++` | 
 
-|===
+|===

spring-cloud-kubernetes-commons/src/main/java/org/springframework/cloud/kubernetes/commons/leader/LeaderProperties.java

@@ -38,6 +38,8 @@ public class LeaderProperties {
 
 	private static final boolean DEFAULT_PUBLISH_FAILED_EVENTS = false;
 
+	private static final boolean DEFAULT_CREATE_CONFIG_MAP = true;
+
 	/**
 	 * Should leader election be enabled. Default: true
 	 */
@@ -79,6 +81,11 @@ public class LeaderProperties {
 	 */
 	private boolean publishFailedEvents = DEFAULT_PUBLISH_FAILED_EVENTS;
 
+	/**
+	 * Enable/disable creating ConfigMap if it does not exist. Default: true
+	 */
+	private boolean createConfigMap = DEFAULT_CREATE_CONFIG_MAP;
+
 	public boolean isEnabled() {
 		return this.enabled;
 	}
@@ -151,4 +158,12 @@ public class LeaderProperties {
 		this.publishFailedEvents = publishFailedEvents;
 	}
 
+	public boolean isCreateConfigMap() {
+		return this.createConfigMap;
+	}
+
+	public void setCreateConfigMap(boolean createConfigMap) {
+		this.createConfigMap = createConfigMap;
+	}
+
 }

spring-cloud-kubernetes-fabric8-leader/src/main/java/org/springframework/cloud/kubernetes/fabric8/leader/Fabric8LeadershipController.java

@@ -51,6 +51,12 @@ public class Fabric8LeadershipController extends LeadershipController {
 	public synchronized void update() {
 		LOGGER.debug("Checking leader state");
 		ConfigMap configMap = getConfigMap();
+		if (configMap == null && !leaderProperties.isCreateConfigMap()) {
+			LOGGER.warn("ConfigMap '{}' does not exist and leaderProperties.isCreateConfigMap() "
+					+ "is false, cannot acquire leadership", leaderProperties.getConfigMapName());
+			notifyOnFailedToAcquire();
+			return;
+		}
 		Leader leader = extractLeader(configMap);
 
 		if (leader != null && isPodReady(leader.getId())) {
@@ -98,6 +104,7 @@ public class Fabric8LeadershipController extends LeadershipController {
 
 		try {
 			Map<String, String> data = getLeaderData(this.candidate);
+
 			if (configMap == null) {
 				createConfigMap(data);
 			}

spring-cloud-kubernetes-fabric8-leader/src/test/java/org/springframework/cloud/kubernetes/fabric8/leader/Fabric8LeadershipControllerTest.java

@@ -17,17 +17,28 @@
 package org.springframework.cloud.kubernetes.fabric8.leader;
 
 import io.fabric8.kubernetes.client.KubernetesClient;
+import io.fabric8.kubernetes.client.dsl.NonNamespaceOperation;
+import io.fabric8.kubernetes.client.dsl.Resource;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Answers;
 import org.mockito.Mock;
+import org.mockito.Mockito;
 import org.mockito.junit.jupiter.MockitoExtension;
 
+import org.springframework.boot.test.system.CapturedOutput;
+import org.springframework.boot.test.system.OutputCaptureExtension;
 import org.springframework.cloud.kubernetes.commons.leader.LeaderProperties;
 import org.springframework.integration.leader.Candidate;
 import org.springframework.integration.leader.event.LeaderEventPublisher;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
 
 /**
  * @author Gytis Trikleris
@@ -44,7 +55,7 @@ public class Fabric8LeadershipControllerTest {
 	@Mock
 	private LeaderEventPublisher mockLeaderEventPublisher;
 
-	@Mock
+	@Mock(answer = Answers.RETURNS_DEEP_STUBS)
 	private KubernetesClient mockKubernetesClient;
 
 	private Fabric8LeadershipController fabric8LeadershipController;
@@ -60,4 +71,40 @@ public class Fabric8LeadershipControllerTest {
 		assertThat(this.fabric8LeadershipController.getLocalLeader().isPresent()).isFalse();
 	}
 
+	@ExtendWith(OutputCaptureExtension.class)
+	@Test
+	void whenNonExistentConfigmapAndCreationNotAllowedStopLeadershipAcquire(CapturedOutput output) {
+		// given
+		String testNamespace = "test-namespace";
+		String testConfigmap = "test-configmap";
+		Resource mockResource = Mockito.mock(Resource.class);
+		NonNamespaceOperation mockNonNamespaceOperation = Mockito.mock(NonNamespaceOperation.class);
+
+		Fabric8LeadershipController fabric8LeadershipController = new Fabric8LeadershipController(mockCandidate,
+				mockLeaderProperties, mockLeaderEventPublisher, mockKubernetesClient);
+
+		when(mockLeaderProperties.isCreateConfigMap()).thenReturn(false);
+		when(mockLeaderProperties.isPublishFailedEvents()).thenReturn(true);
+		when(mockLeaderProperties.getConfigMapName()).thenReturn(testConfigmap);
+		when(mockKubernetesClient.getNamespace()).thenReturn(testNamespace);
+		when(mockLeaderProperties.getNamespace(anyString())).thenReturn(testNamespace);
+		when(mockKubernetesClient.configMaps().inNamespace(anyString())).thenReturn(mockNonNamespaceOperation);
+		when(mockNonNamespaceOperation.withName(any())).thenReturn(mockResource);
+		when(mockResource.get()).thenReturn(null);
+
+		// when
+		fabric8LeadershipController.update();
+
+		// then
+		assertThat(output).contains("ConfigMap '" + testConfigmap + "' does not exist "
+				+ "and leaderProperties.isCreateConfigMap() is false, cannot acquire leadership");
+		verify(mockLeaderEventPublisher).publishOnFailedToAcquire(any(), any(), any());
+
+		verify(mockKubernetesClient, never()).pods();
+		verify(mockCandidate, never()).getId();
+		verify(mockLeaderProperties, never()).getLeaderIdPrefix();
+		verify(mockLeaderEventPublisher, never()).publishOnGranted(any(), any(), any());
+		verify(mockLeaderEventPublisher, never()).publishOnRevoked(any(), any(), any());
+	}
+
 }