tillrohrmann commented on a change in pull request #17485: URL: https://github.com/apache/flink/pull/17485#discussion_r791722429
########## File path: flink-kubernetes/src/main/java/org/apache/flink/kubernetes/highavailability/KubernetesMultipleComponentLeaderElectionDriver.java ########## @@ -0,0 +1,268 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you 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 + * + * http://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.apache.flink.kubernetes.highavailability; + +import org.apache.flink.kubernetes.configuration.KubernetesLeaderElectionConfiguration; +import org.apache.flink.kubernetes.kubeclient.FlinkKubeClient; +import org.apache.flink.kubernetes.kubeclient.KubernetesConfigMapSharedWatcher; +import org.apache.flink.kubernetes.kubeclient.KubernetesSharedWatcher; +import org.apache.flink.kubernetes.kubeclient.resources.KubernetesConfigMap; +import org.apache.flink.kubernetes.kubeclient.resources.KubernetesException; +import org.apache.flink.kubernetes.kubeclient.resources.KubernetesLeaderElector; +import org.apache.flink.kubernetes.utils.KubernetesUtils; +import org.apache.flink.runtime.leaderelection.LeaderElectionException; +import org.apache.flink.runtime.leaderelection.LeaderInformation; +import org.apache.flink.runtime.leaderelection.LeaderInformationWithComponentId; +import org.apache.flink.runtime.leaderelection.MultipleComponentLeaderElectionDriver; +import org.apache.flink.runtime.rpc.FatalErrorHandler; +import org.apache.flink.util.Preconditions; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.util.ArrayList; +import java.util.Collection; +import java.util.List; +import java.util.Map; +import java.util.Optional; +import java.util.concurrent.Executor; +import java.util.concurrent.atomic.AtomicBoolean; +import java.util.function.Function; + +import static org.apache.flink.kubernetes.utils.Constants.LABEL_CONFIGMAP_TYPE_HIGH_AVAILABILITY; +import static org.apache.flink.kubernetes.utils.KubernetesUtils.checkConfigMaps; + +/** {@link MultipleComponentLeaderElectionDriver} for Kubernetes. */ +public class KubernetesMultipleComponentLeaderElectionDriver + implements MultipleComponentLeaderElectionDriver { + + private static final Logger LOG = + LoggerFactory.getLogger(KubernetesMultipleComponentLeaderElectionDriver.class); + + private final FlinkKubeClient kubeClient; + + private final String configMapName; + + private final String lockIdentity; + + private final MultipleComponentLeaderElectionDriver.Listener leaderElectionListener; + + private final KubernetesLeaderElector leaderElector; + + // Labels will be used to clean up the ha related ConfigMaps. + private final Map<String, String> configMapLabels; + + private final FatalErrorHandler fatalErrorHandler; + + private final KubernetesSharedWatcher.Watch kubernetesWatch; + + private AtomicBoolean running = new AtomicBoolean(true); + + public KubernetesMultipleComponentLeaderElectionDriver( + KubernetesLeaderElectionConfiguration leaderElectionConfiguration, + FlinkKubeClient kubeClient, + Listener leaderElectionListener, + KubernetesConfigMapSharedWatcher configMapSharedWatcher, + Executor watchExecutor, + FatalErrorHandler fatalErrorHandler) { + this.kubeClient = kubeClient; + this.leaderElectionListener = leaderElectionListener; + this.fatalErrorHandler = fatalErrorHandler; + + this.configMapName = leaderElectionConfiguration.getConfigMapName(); + this.lockIdentity = leaderElectionConfiguration.getLockIdentity(); + + this.leaderElector = + kubeClient.createLeaderElector( + leaderElectionConfiguration, new LeaderCallbackHandlerImpl()); + + this.configMapLabels = + KubernetesUtils.getConfigMapLabels( + leaderElectionConfiguration.getClusterId(), + LABEL_CONFIGMAP_TYPE_HIGH_AVAILABILITY); + + kubernetesWatch = + configMapSharedWatcher.watch( + configMapName, new ConfigMapCallbackHandlerImpl(), watchExecutor); + + leaderElector.run(); + } + + @Override + public void close() throws Exception { + if (running.compareAndSet(true, false)) { + LOG.info("Closing {}.", this); + + leaderElector.stop(); + kubernetesWatch.close(); + } + } + + @Override + public boolean hasLeadership() { + Preconditions.checkState(running.get()); + final Optional<KubernetesConfigMap> optionalConfigMap = + kubeClient.getConfigMap(configMapName); + + if (optionalConfigMap.isPresent()) { + return KubernetesLeaderElector.hasLeadership(optionalConfigMap.get(), lockIdentity); + } else { + fatalErrorHandler.onFatalError( + new KubernetesException( + String.format( + "ConfigMap %s does not exist. This indicates that somebody has interfered with Flink's operation.", + configMapName))); + return false; + } + } + + @Override + public void publishLeaderInformation(String componentId, LeaderInformation leaderInformation) + throws Exception { + Preconditions.checkState(running.get()); + + kubeClient + .checkAndUpdateConfigMap( + configMapName, + updateConfigMapWithLeaderInformation(componentId, leaderInformation)) + .get(); + + LOG.debug( + "Successfully wrote leader information {} for leader {} into the config map {}.", + leaderInformation, + componentId, + configMapName); + } + + @Override + public void deleteLeaderInformation(String componentId) throws Exception { + publishLeaderInformation(componentId, LeaderInformation.empty()); + } + + private Function<KubernetesConfigMap, Optional<KubernetesConfigMap>> + updateConfigMapWithLeaderInformation( + String leaderName, LeaderInformation leaderInformation) { + final String configMapDataKey = KubernetesUtils.createSingleLeaderKey(leaderName); + + return kubernetesConfigMap -> { + if (KubernetesLeaderElector.hasLeadership(kubernetesConfigMap, lockIdentity)) { + final Map<String, String> data = kubernetesConfigMap.getData(); + + if (leaderInformation.isEmpty()) { + data.remove(configMapDataKey); + } else { + data.put( + configMapDataKey, + KubernetesUtils.encodeLeaderInformation(leaderInformation)); + } + + kubernetesConfigMap.getLabels().putAll(configMapLabels); + return Optional.of(kubernetesConfigMap); + } + + return Optional.empty(); + }; + } + + private static Collection<LeaderInformationWithComponentId> extractLeaderInformation( + KubernetesConfigMap configMap) { + final Map<String, String> data = configMap.getData(); + + final Collection<LeaderInformationWithComponentId> leaderInformationWithLeaderNames = + new ArrayList<>(); + + for (Map.Entry<String, String> keyValuePair : data.entrySet()) { + final String key = keyValuePair.getKey(); + if (KubernetesUtils.isSingleLeaderKey(key)) { + final String leaderName = KubernetesUtils.extractLeaderName(key); + final LeaderInformation leaderInformation = + KubernetesUtils.parseLeaderInformationSafely(keyValuePair.getValue()); Review comment: I think this is ok because the corresponding `DefaultLeaderElectionService` would issue another publish command if it is the leader and its leader information is empty. -- This is an automated message from the Apache Git Service. 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