YARN-6900. ZooKeeper based implementation of the FederationStateStore. (Íñigo Goiri via Subru).

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/main/java/org/apache/hadoop/yarn/conf/YarnConfiguration.java

@@ -2629,6 +2629,14 @@ public class YarnConfiguration extends Configuration {
 
   public static final String DEFAULT_FEDERATION_POLICY_MANAGER_PARAMS = "";
 
+  public static final String FEDERATION_STATESTORE_ZK_PREFIX =
+      FEDERATION_PREFIX + "zk-state-store.";
+  /** Parent znode path under which ZKRMStateStore will create znodes. */
+  public static final String FEDERATION_STATESTORE_ZK_PARENT_PATH =
+      FEDERATION_STATESTORE_ZK_PREFIX + "parent-path";
+  public static final String DEFAULT_FEDERATION_STATESTORE_ZK_PARENT_PATH =
+      "/federationstore";
+
   private static final String FEDERATION_STATESTORE_SQL_PREFIX =
       FEDERATION_PREFIX + "state-store.sql.";
 

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/test/java/org/apache/hadoop/yarn/conf/TestYarnConfigurationFields.java

@@ -96,6 +96,10 @@ public class TestYarnConfigurationFields extends TestConfigurationFieldsBase {
     configurationPropsToSkipCompare
         .add(YarnConfiguration.DEFAULT_FEDERATION_POLICY_MANAGER_PARAMS);
 
+    // Federation StateStore ZK implementation configs to be ignored
+    configurationPropsToSkipCompare.add(
+        YarnConfiguration.FEDERATION_STATESTORE_ZK_PARENT_PATH);
+
     // Federation StateStore SQL implementation configs to be ignored
     configurationPropsToSkipCompare
         .add(YarnConfiguration.FEDERATION_STATESTORE_SQL_JDBC_CLASS);

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-common/pom.xml

@@ -130,6 +130,11 @@
         </exclusion>
       </exclusions>
     </dependency>
+    <dependency>
+      <groupId>org.apache.curator</groupId>
+      <artifactId>curator-test</artifactId>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
 
   <build>

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-common/src/main/java/org/apache/hadoop/yarn/server/federation/store/impl/ZookeeperFederationStateStore.java

@@ -0,0 +1,634 @@
+/**
+ * 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
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.hadoop.yarn.server.federation.store.impl;
+
+import static org.apache.hadoop.util.curator.ZKCuratorManager.getNodePath;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Calendar;
+import java.util.List;
+import java.util.TimeZone;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.util.curator.ZKCuratorManager;
+import org.apache.hadoop.yarn.api.records.ApplicationId;
+import org.apache.hadoop.yarn.conf.YarnConfiguration;
+import org.apache.hadoop.yarn.exceptions.YarnException;
+import org.apache.hadoop.yarn.federation.proto.YarnServerFederationProtos.SubClusterIdProto;
+import org.apache.hadoop.yarn.federation.proto.YarnServerFederationProtos.SubClusterInfoProto;
+import org.apache.hadoop.yarn.federation.proto.YarnServerFederationProtos.SubClusterPolicyConfigurationProto;
+import org.apache.hadoop.yarn.server.federation.store.FederationStateStore;
+import org.apache.hadoop.yarn.server.federation.store.records.AddApplicationHomeSubClusterRequest;
+import org.apache.hadoop.yarn.server.federation.store.records.AddApplicationHomeSubClusterResponse;
+import org.apache.hadoop.yarn.server.federation.store.records.ApplicationHomeSubCluster;
+import org.apache.hadoop.yarn.server.federation.store.records.DeleteApplicationHomeSubClusterRequest;
+import org.apache.hadoop.yarn.server.federation.store.records.DeleteApplicationHomeSubClusterResponse;
+import org.apache.hadoop.yarn.server.federation.store.records.GetApplicationHomeSubClusterRequest;
+import org.apache.hadoop.yarn.server.federation.store.records.GetApplicationHomeSubClusterResponse;
+import org.apache.hadoop.yarn.server.federation.store.records.GetApplicationsHomeSubClusterRequest;
+import org.apache.hadoop.yarn.server.federation.store.records.GetApplicationsHomeSubClusterResponse;
+import org.apache.hadoop.yarn.server.federation.store.records.GetSubClusterInfoRequest;
+import org.apache.hadoop.yarn.server.federation.store.records.GetSubClusterInfoResponse;
+import org.apache.hadoop.yarn.server.federation.store.records.GetSubClusterPoliciesConfigurationsRequest;
+import org.apache.hadoop.yarn.server.federation.store.records.GetSubClusterPoliciesConfigurationsResponse;
+import org.apache.hadoop.yarn.server.federation.store.records.GetSubClusterPolicyConfigurationRequest;
+import org.apache.hadoop.yarn.server.federation.store.records.GetSubClusterPolicyConfigurationResponse;
+import org.apache.hadoop.yarn.server.federation.store.records.GetSubClustersInfoRequest;
+import org.apache.hadoop.yarn.server.federation.store.records.GetSubClustersInfoResponse;
+import org.apache.hadoop.yarn.server.federation.store.records.SetSubClusterPolicyConfigurationRequest;
+import org.apache.hadoop.yarn.server.federation.store.records.SetSubClusterPolicyConfigurationResponse;
+import org.apache.hadoop.yarn.server.federation.store.records.SubClusterDeregisterRequest;
+import org.apache.hadoop.yarn.server.federation.store.records.SubClusterDeregisterResponse;
+import org.apache.hadoop.yarn.server.federation.store.records.SubClusterHeartbeatRequest;
+import org.apache.hadoop.yarn.server.federation.store.records.SubClusterHeartbeatResponse;
+import org.apache.hadoop.yarn.server.federation.store.records.SubClusterId;
+import org.apache.hadoop.yarn.server.federation.store.records.SubClusterInfo;
+import org.apache.hadoop.yarn.server.federation.store.records.SubClusterPolicyConfiguration;
+import org.apache.hadoop.yarn.server.federation.store.records.SubClusterRegisterRequest;
+import org.apache.hadoop.yarn.server.federation.store.records.SubClusterRegisterResponse;
+import org.apache.hadoop.yarn.server.federation.store.records.SubClusterState;
+import org.apache.hadoop.yarn.server.federation.store.records.UpdateApplicationHomeSubClusterRequest;
+import org.apache.hadoop.yarn.server.federation.store.records.UpdateApplicationHomeSubClusterResponse;
+import org.apache.hadoop.yarn.server.federation.store.records.impl.pb.SubClusterIdPBImpl;
+import org.apache.hadoop.yarn.server.federation.store.records.impl.pb.SubClusterInfoPBImpl;
+import org.apache.hadoop.yarn.server.federation.store.records.impl.pb.SubClusterPolicyConfigurationPBImpl;
+import org.apache.hadoop.yarn.server.federation.store.utils.FederationApplicationHomeSubClusterStoreInputValidator;
+import org.apache.hadoop.yarn.server.federation.store.utils.FederationMembershipStateStoreInputValidator;
+import org.apache.hadoop.yarn.server.federation.store.utils.FederationPolicyStoreInputValidator;
+import org.apache.hadoop.yarn.server.federation.store.utils.FederationStateStoreUtils;
+import org.apache.hadoop.yarn.server.records.Version;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.protobuf.InvalidProtocolBufferException;
+
+/**
+ * ZooKeeper implementation of {@link FederationStateStore}.
+ *
+ * The znode structure is as follows:
+ * ROOT_DIR_PATH
+ * |--- MEMBERSHIP
+ * |     |----- SC1
+ * |     |----- SC2
+ * |--- APPLICATION
+ * |     |----- APP1
+ * |     |----- APP2
+ * |--- POLICY
+ *       |----- QUEUE1
+ *       |----- QUEUE1
+ */
+public class ZookeeperFederationStateStore implements FederationStateStore {
+
+  private static final Logger LOG =
+      LoggerFactory.getLogger(ZookeeperFederationStateStore.class);
+
+  private final static String ROOT_ZNODE_NAME_MEMBERSHIP = "memberships";
+  private final static String ROOT_ZNODE_NAME_APPLICATION = "applications";
+  private final static String ROOT_ZNODE_NAME_POLICY = "policies";
+
+  /** Interface to Zookeeper. */
+  private ZKCuratorManager zkManager;
+
+  /** Directory to store the state store data. */
+  private String baseZNode;
+
+  private String appsZNode;
+  private String membershipZNode;
+  private String policiesZNode;
+
+  @Override
+  public void init(Configuration conf) throws YarnException {
+    LOG.info("Initializing ZooKeeper connection");
+
+    baseZNode = conf.get(
+        YarnConfiguration.FEDERATION_STATESTORE_ZK_PARENT_PATH,
+        YarnConfiguration.DEFAULT_FEDERATION_STATESTORE_ZK_PARENT_PATH);
+    try {
+      this.zkManager = new ZKCuratorManager(conf);
+      this.zkManager.start();
+    } catch (IOException e) {
+      LOG.error("Cannot initialize the ZK connection", e);
+    }
+
+    // Base znodes
+    membershipZNode = getNodePath(baseZNode, ROOT_ZNODE_NAME_MEMBERSHIP);
+    appsZNode = getNodePath(baseZNode, ROOT_ZNODE_NAME_APPLICATION);
+    policiesZNode = getNodePath(baseZNode, ROOT_ZNODE_NAME_POLICY);
+
+    // Create base znode for each entity
+    try {
+      zkManager.createRootDirRecursively(membershipZNode);
+      zkManager.createRootDirRecursively(appsZNode);
+      zkManager.createRootDirRecursively(policiesZNode);
+    } catch (Exception e) {
+      String errMsg = "Cannot create base directories: " + e.getMessage();
+      FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
+    }
+
+  }
+
+  @Override
+  public void close() throws Exception {
+    if (zkManager != null) {
+      zkManager.close();
+    }
+  }
+
+  @Override
+  public AddApplicationHomeSubClusterResponse addApplicationHomeSubCluster(
+      AddApplicationHomeSubClusterRequest request) throws YarnException {
+
+    FederationApplicationHomeSubClusterStoreInputValidator.validate(request);
+    ApplicationHomeSubCluster app = request.getApplicationHomeSubCluster();
+    ApplicationId appId = app.getApplicationId();
+
+    // Try to write the subcluster
+    SubClusterId homeSubCluster = app.getHomeSubCluster();
+    try {
+      putApp(appId, homeSubCluster, false);
+    } catch (Exception e) {
+      String errMsg = "Cannot add application home subcluster for " + appId;
+      FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
+    }
+
+    // Check for the actual subcluster
+    try {
+      homeSubCluster = getApp(appId);
+    } catch (Exception e) {
+      String errMsg = "Cannot check app home subcluster for " + appId;
+      FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
+    }
+
+    return AddApplicationHomeSubClusterResponse
+        .newInstance(homeSubCluster);
+  }
+
+  @Override
+  public UpdateApplicationHomeSubClusterResponse
+      updateApplicationHomeSubCluster(
+          UpdateApplicationHomeSubClusterRequest request)
+              throws YarnException {
+
+    FederationApplicationHomeSubClusterStoreInputValidator.validate(request);
+    ApplicationHomeSubCluster app = request.getApplicationHomeSubCluster();
+    ApplicationId appId = app.getApplicationId();
+    SubClusterId homeSubCluster = getApp(appId);
+    if (homeSubCluster == null) {
+      String errMsg = "Application " + appId + " does not exist";
+      FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
+    }
+    SubClusterId newSubClusterId =
+        request.getApplicationHomeSubCluster().getHomeSubCluster();
+    putApp(appId, newSubClusterId, true);
+    return UpdateApplicationHomeSubClusterResponse.newInstance();
+  }
+
+  @Override
+  public GetApplicationHomeSubClusterResponse getApplicationHomeSubCluster(
+      GetApplicationHomeSubClusterRequest request) throws YarnException {
+
+    FederationApplicationHomeSubClusterStoreInputValidator.validate(request);
+    ApplicationId appId = request.getApplicationId();
+    SubClusterId homeSubCluster = getApp(appId);
+    if (homeSubCluster == null) {
+      String errMsg = "Application " + appId + " does not exist";
+      FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
+    }
+    return GetApplicationHomeSubClusterResponse.newInstance(
+        ApplicationHomeSubCluster.newInstance(appId, homeSubCluster));
+  }
+
+  @Override
+  public GetApplicationsHomeSubClusterResponse getApplicationsHomeSubCluster(
+      GetApplicationsHomeSubClusterRequest request) throws YarnException {
+    List<ApplicationHomeSubCluster> result = new ArrayList<>();
+
+    try {
+      for (String child : zkManager.getChildren(appsZNode)) {
+        ApplicationId appId = ApplicationId.fromString(child);
+        SubClusterId homeSubCluster = getApp(appId);
+        ApplicationHomeSubCluster app =
+            ApplicationHomeSubCluster.newInstance(appId, homeSubCluster);
+        result.add(app);
+      }
+    } catch (Exception e) {
+      String errMsg = "Cannot get apps: " + e.getMessage();
+      FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
+    }
+
+    return GetApplicationsHomeSubClusterResponse.newInstance(result);
+  }
+
+  @Override
+  public DeleteApplicationHomeSubClusterResponse
+      deleteApplicationHomeSubCluster(
+          DeleteApplicationHomeSubClusterRequest request)
+              throws YarnException {
+
+    FederationApplicationHomeSubClusterStoreInputValidator.validate(request);
+    ApplicationId appId = request.getApplicationId();
+    String appZNode = getNodePath(appsZNode, appId.toString());
+
+    boolean exists = false;
+    try {
+      exists = zkManager.exists(appZNode);
+    } catch (Exception e) {
+      String errMsg = "Cannot check app: " + e.getMessage();
+      FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
+    }
+    if (!exists) {
+      String errMsg = "Application " + appId + " does not exist";
+      FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
+    }
+
+    try {
+      zkManager.delete(appZNode);
+    } catch (Exception e) {
+      String errMsg = "Cannot delete app: " + e.getMessage();
+      FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
+    }
+
+    return DeleteApplicationHomeSubClusterResponse.newInstance();
+  }
+
+  @Override
+  public SubClusterRegisterResponse registerSubCluster(
+      SubClusterRegisterRequest request) throws YarnException {
+    FederationMembershipStateStoreInputValidator.validate(request);
+    SubClusterInfo subClusterInfo = request.getSubClusterInfo();
+    SubClusterId subclusterId = subClusterInfo.getSubClusterId();
+
+    // Update the heartbeat time
+    long currentTime = getCurrentTime();
+    subClusterInfo.setLastHeartBeat(currentTime);
+
+    try {
+      putSubclusterInfo(subclusterId, subClusterInfo, true);
+    } catch (Exception e) {
+      String errMsg = "Cannot register subcluster: " + e.getMessage();
+      FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
+    }
+    return SubClusterRegisterResponse.newInstance();
+  }
+
+  @Override
+  public SubClusterDeregisterResponse deregisterSubCluster(
+      SubClusterDeregisterRequest request) throws YarnException {
+    FederationMembershipStateStoreInputValidator.validate(request);
+    SubClusterId subClusterId = request.getSubClusterId();
+    SubClusterState state = request.getState();
+
+    // Get the current information and update it
+    SubClusterInfo subClusterInfo = getSubclusterInfo(subClusterId);
+    if (subClusterInfo == null) {
+      String errMsg = "SubCluster " + subClusterId + " not found";
+      FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
+    } else {
+      subClusterInfo.setState(state);
+      putSubclusterInfo(subClusterId, subClusterInfo, true);
+    }
+
+    return SubClusterDeregisterResponse.newInstance();
+  }
+
+  @Override
+  public SubClusterHeartbeatResponse subClusterHeartbeat(
+      SubClusterHeartbeatRequest request) throws YarnException {
+
+    FederationMembershipStateStoreInputValidator.validate(request);
+    SubClusterId subClusterId = request.getSubClusterId();
+
+    SubClusterInfo subClusterInfo = getSubclusterInfo(subClusterId);
+    if (subClusterInfo == null) {
+      String errMsg = "SubCluster " + subClusterId
+          + " does not exist; cannot heartbeat";
+      FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
+    }
+
+    long currentTime = getCurrentTime();
+    subClusterInfo.setLastHeartBeat(currentTime);
+    subClusterInfo.setState(request.getState());
+    subClusterInfo.setCapability(request.getCapability());
+
+    putSubclusterInfo(subClusterId, subClusterInfo, true);
+
+    return SubClusterHeartbeatResponse.newInstance();
+  }
+
+  @Override
+  public GetSubClusterInfoResponse getSubCluster(
+      GetSubClusterInfoRequest request) throws YarnException {
+
+    FederationMembershipStateStoreInputValidator.validate(request);
+    SubClusterId subClusterId = request.getSubClusterId();
+    SubClusterInfo subClusterInfo = null;
+    try {
+      subClusterInfo = getSubclusterInfo(subClusterId);
+      if (subClusterInfo == null) {
+        LOG.warn("The queried SubCluster: {} does not exist.", subClusterId);
+        return null;
+      }
+    } catch (Exception e) {
+      String errMsg = "Cannot get subcluster: " + e.getMessage();
+      FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
+    }
+    return GetSubClusterInfoResponse.newInstance(subClusterInfo);
+  }
+
+  @Override
+  public GetSubClustersInfoResponse getSubClusters(
+      GetSubClustersInfoRequest request) throws YarnException {
+    List<SubClusterInfo> result = new ArrayList<>();
+
+    try {
+      for (String child : zkManager.getChildren(membershipZNode)) {
+        SubClusterId subClusterId = SubClusterId.newInstance(child);
+        SubClusterInfo info = getSubclusterInfo(subClusterId);
+        if (!request.getFilterInactiveSubClusters() ||
+            info.getState().isActive()) {
+          result.add(info);
+        }
+      }
+    } catch (Exception e) {
+      String errMsg = "Cannot get subclusters: " + e.getMessage();
+      FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
+    }
+    return GetSubClustersInfoResponse.newInstance(result);
+  }
+
+
+  @Override
+  public GetSubClusterPolicyConfigurationResponse getPolicyConfiguration(
+      GetSubClusterPolicyConfigurationRequest request) throws YarnException {
+
+    FederationPolicyStoreInputValidator.validate(request);
+    String queue = request.getQueue();
+    SubClusterPolicyConfiguration policy = null;
+    try {
+      policy = getPolicy(queue);
+    } catch (Exception e) {
+      String errMsg = "Cannot get policy: " + e.getMessage();
+      FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
+    }
+
+    if (policy == null) {
+      LOG.warn("Policy for queue: {} does not exist.", queue);
+      return null;
+    }
+    return GetSubClusterPolicyConfigurationResponse
+        .newInstance(policy);
+  }
+
+  @Override
+  public SetSubClusterPolicyConfigurationResponse setPolicyConfiguration(
+      SetSubClusterPolicyConfigurationRequest request) throws YarnException {
+
+    FederationPolicyStoreInputValidator.validate(request);
+    SubClusterPolicyConfiguration policy =
+        request.getPolicyConfiguration();
+    try {
+      String queue = policy.getQueue();
+      putPolicy(queue, policy, true);
+    } catch (Exception e) {
+      String errMsg = "Cannot set policy: " + e.getMessage();
+      FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
+    }
+    return SetSubClusterPolicyConfigurationResponse.newInstance();
+  }
+
+  @Override
+  public GetSubClusterPoliciesConfigurationsResponse getPoliciesConfigurations(
+      GetSubClusterPoliciesConfigurationsRequest request) throws YarnException {
+    List<SubClusterPolicyConfiguration> result = new ArrayList<>();
+
+    try {
+      for (String child : zkManager.getChildren(policiesZNode)) {
+        SubClusterPolicyConfiguration policy = getPolicy(child);
+        result.add(policy);
+      }
+    } catch (Exception e) {
+      String errMsg = "Cannot get policies: " + e.getMessage();
+      FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
+    }
+    return GetSubClusterPoliciesConfigurationsResponse.newInstance(result);
+  }
+
+  @Override
+  public Version getCurrentVersion() {
+    return null;
+  }
+
+  @Override
+  public Version loadVersion() {
+    return null;
+  }
+
+  /**
+   * Get the subcluster for an application.
+   * @param appId Application identifier.
+   * @return Subcluster identifier.
+   * @throws Exception If it cannot contact ZooKeeper.
+   */
+  private SubClusterId getApp(final ApplicationId appId) throws YarnException {
+    String appZNode = getNodePath(appsZNode, appId.toString());
+
+    SubClusterId subClusterId = null;
+    byte[] data = get(appZNode);
+    if (data != null) {
+      try {
+        subClusterId = new SubClusterIdPBImpl(
+            SubClusterIdProto.parseFrom(data));
+      } catch (InvalidProtocolBufferException e) {
+        String errMsg = "Cannot parse application at " + appZNode;
+        FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
+      }
+    }
+    return subClusterId;
+  }
+
+  /**
+   * Put an application.
+   * @param appId Application identifier.
+   * @param subClusterId Subcluster identifier.
+   * @throws Exception If it cannot contact ZooKeeper.
+   */
+  private void putApp(final ApplicationId appId,
+      final SubClusterId subClusterId, boolean update)
+          throws YarnException {
+    String appZNode = getNodePath(appsZNode, appId.toString());
+    SubClusterIdProto proto =
+        ((SubClusterIdPBImpl)subClusterId).getProto();
+    byte[] data = proto.toByteArray();
+    put(appZNode, data, update);
+  }
+
+  /**
+   * Get the current information for a subcluster from Zookeeper.
+   * @param subclusterId Subcluster identifier.
+   * @return Subcluster information or null if it doesn't exist.
+   * @throws Exception If it cannot contact ZooKeeper.
+   */
+  private SubClusterInfo getSubclusterInfo(final SubClusterId subclusterId)
+      throws YarnException {
+    String memberZNode = getNodePath(membershipZNode, subclusterId.toString());
+
+    SubClusterInfo policy = null;
+    byte[] data = get(memberZNode);
+    if (data != null) {
+      try {
+        policy = new SubClusterInfoPBImpl(
+            SubClusterInfoProto.parseFrom(data));
+      } catch (InvalidProtocolBufferException e) {
+        String errMsg = "Cannot parse subcluster info at " + memberZNode;
+        FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
+      }
+    }
+    return policy;
+  }
+
+  /**
+   * Put the subcluster information in Zookeeper.
+   * @param subclusterId Subcluster identifier.
+   * @param subClusterInfo Subcluster information.
+   * @throws Exception If it cannot contact ZooKeeper.
+   */
+  private void putSubclusterInfo(final SubClusterId subclusterId,
+      final SubClusterInfo subClusterInfo, final boolean update)
+          throws YarnException {
+    String memberZNode = getNodePath(membershipZNode, subclusterId.toString());
+    SubClusterInfoProto proto =
+        ((SubClusterInfoPBImpl)subClusterInfo).getProto();
+    byte[] data = proto.toByteArray();
+    put(memberZNode, data, update);
+  }
+
+  /**
+   * Get the queue policy from Zookeeper.
+   * @param queue Name of the queue.
+   * @return Subcluster policy configuration.
+   * @throws YarnException If it cannot contact ZooKeeper.
+   */
+  private SubClusterPolicyConfiguration getPolicy(final String queue)
+      throws YarnException {
+    String policyZNode = getNodePath(policiesZNode, queue);
+
+    SubClusterPolicyConfiguration policy = null;
+    byte[] data = get(policyZNode);
+    if (data != null) {
+      try {
+        policy = new SubClusterPolicyConfigurationPBImpl(
+            SubClusterPolicyConfigurationProto.parseFrom(data));
+      } catch (InvalidProtocolBufferException e) {
+        String errMsg = "Cannot parse policy at " + policyZNode;
+        FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
+      }
+    }
+    return policy;
+  }
+
+  /**
+   * Put the subcluster information in Zookeeper.
+   * @param queue Name of the queue.
+   * @param policy Subcluster policy configuration.
+   * @throws YarnException If it cannot contact ZooKeeper.
+   */
+  private void putPolicy(final String queue,
+      final SubClusterPolicyConfiguration policy, boolean update)
+          throws YarnException {
+    String policyZNode = getNodePath(policiesZNode, queue);
+
+    SubClusterPolicyConfigurationProto proto =
+        ((SubClusterPolicyConfigurationPBImpl)policy).getProto();
+    byte[] data = proto.toByteArray();
+    put(policyZNode, data, update);
+  }
+
+  /**
+   * Get data from a znode in Zookeeper.
+   * @param znode Path of the znode.
+   * @return Data in the znode.
+   * @throws YarnException If it cannot contact ZooKeeper.
+   */
+  private byte[] get(String znode) throws YarnException {
+    boolean exists = false;
+    try {
+      exists = zkManager.exists(znode);
+    } catch (Exception e) {
+      String errMsg = "Cannot find znode " + znode;
+      FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
+    }
+    if (!exists) {
+      LOG.error("{} does not exist", znode);
+      return null;
+    }
+
+    byte[] data = null;
+    try {
+      data = zkManager.getData(znode);
+    } catch (Exception e) {
+      String errMsg = "Cannot get data from znode " + znode
+          + ": " + e.getMessage();
+      FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
+    }
+    return data;
+  }
+
+  /**
+   * Put data into a znode in Zookeeper.
+   * @param znode Path of the znode.
+   * @param data Data to write.
+   * @throws YarnException If it cannot contact ZooKeeper.
+   */
+  private void put(String znode, byte[] data, boolean update)
+      throws YarnException {
+    // Create the znode
+    boolean created = false;
+    try {
+      created = zkManager.create(znode);
+    } catch (Exception e) {
+      String errMsg = "Cannot create znode " + znode + ": " + e.getMessage();
+      FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
+    }
+    if (!created) {
+      LOG.debug("{} not created", znode);
+      if (!update) {
+        LOG.info("{} already existed and we are not updating", znode);
+        return;
+      }
+    }
+
+    // Write the data into the znode
+    try {
+      zkManager.setData(znode, data, -1);
+    } catch (Exception e) {
+      String errMsg = "Cannot write data into znode " + znode
+          + ": " + e.getMessage();
+      FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
+    }
+  }
+
+  /**
+   * Get the current time.
+   * @return Current time in milliseconds.
+   */
+  private static long getCurrentTime() {
+    Calendar cal = Calendar.getInstance(TimeZone.getTimeZone("UTC"));
+    return cal.getTimeInMillis();
+  }
+}

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-common/src/test/java/org/apache/hadoop/yarn/server/federation/store/impl/TestZookeeperFederationStateStore.java

@@ -0,0 +1,89 @@
+/**
+ * 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
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.hadoop.yarn.server.federation.store.impl;
+
+import java.io.IOException;
+
+import org.apache.curator.framework.CuratorFramework;
+import org.apache.curator.framework.CuratorFrameworkFactory;
+import org.apache.curator.retry.RetryNTimes;
+import org.apache.curator.test.TestingServer;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.CommonConfigurationKeys;
+import org.apache.hadoop.yarn.conf.YarnConfiguration;
+import org.apache.hadoop.yarn.exceptions.YarnException;
+import org.apache.hadoop.yarn.server.federation.store.FederationStateStore;
+import org.junit.After;
+import org.junit.Before;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Unit tests for ZookeeperFederationStateStore.
+ */
+public class TestZookeeperFederationStateStore
+    extends FederationStateStoreBaseTest {
+
+  private static final Logger LOG =
+      LoggerFactory.getLogger(TestZookeeperFederationStateStore.class);
+
+  /** Zookeeper test server. */
+  private static TestingServer curatorTestingServer;
+  private static CuratorFramework curatorFramework;
+
+  @Before
+  public void before() throws IOException, YarnException {
+    try {
+      curatorTestingServer = new TestingServer();
+      curatorTestingServer.start();
+      String connectString = curatorTestingServer.getConnectString();
+      curatorFramework = CuratorFrameworkFactory.builder()
+          .connectString(connectString)
+          .retryPolicy(new RetryNTimes(100, 100))
+          .build();
+      curatorFramework.start();
+
+      Configuration conf = new YarnConfiguration();
+      conf.set(CommonConfigurationKeys.ZK_ADDRESS, connectString);
+      setConf(conf);
+    } catch (Exception e) {
+      LOG.error("Cannot initialize ZooKeeper store", e);
+      throw new IOException(e);
+    }
+
+    super.before();
+  }
+
+  @After
+  public void after() throws Exception {
+    super.after();
+
+    curatorFramework.close();
+    try {
+      curatorTestingServer.stop();
+    } catch (IOException e) {
+    }
+  }
+
+  @Override
+  protected FederationStateStore createStateStore() {
+    Configuration conf = new Configuration();
+    super.setConf(conf);
+    return new ZookeeperFederationStateStore();
+  }
+}

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-common/src/test/java/org/apache/hadoop/yarn/server/federation/utils/TestFederationStateStoreFacadeRetry.java

@@ -28,6 +28,7 @@ import org.apache.hadoop.yarn.server.federation.store.exception.FederationStateS
 import org.apache.hadoop.yarn.server.federation.store.exception.FederationStateStoreInvalidInputException;
 import org.apache.hadoop.yarn.server.federation.store.exception.FederationStateStoreRetriableException;
 import org.junit.Assert;
+import org.junit.Before;
 import org.junit.Test;
 
 import com.zaxxer.hikari.pool.HikariPool.PoolInitializationException;
@@ -40,14 +41,18 @@ public class TestFederationStateStoreFacadeRetry {
   private int maxRetries = 4;
   private Configuration conf;
 
+  @Before
+  public void setup() {
+    conf = new Configuration();
+    conf.setInt(YarnConfiguration.CLIENT_FAILOVER_RETRIES, maxRetries);
+  }
+
   /*
    * Test to validate that FederationStateStoreRetriableException is a retriable
    * exception.
    */
   @Test
   public void testFacadeRetriableException() throws Exception {
-    conf = new Configuration();
-    conf.setInt(YarnConfiguration.CLIENT_FAILOVER_RETRIES, maxRetries);
     RetryPolicy policy = FederationStateStoreFacade.createRetryPolicy(conf);
     RetryAction action = policy.shouldRetry(
         new FederationStateStoreRetriableException(""), 0, 0, false);
@@ -66,9 +71,6 @@ public class TestFederationStateStoreFacadeRetry {
    */
   @Test
   public void testFacadeYarnException() throws Exception {
-
-    conf = new Configuration();
-    conf.setInt(YarnConfiguration.CLIENT_FAILOVER_RETRIES, maxRetries);
     RetryPolicy policy = FederationStateStoreFacade.createRetryPolicy(conf);
     RetryAction action = policy.shouldRetry(new YarnException(), 0, 0, false);
     Assert.assertEquals(RetryAction.FAIL.action, action.action);
@@ -80,8 +82,6 @@ public class TestFederationStateStoreFacadeRetry {
    */
   @Test
   public void testFacadeStateStoreException() throws Exception {
-    conf = new Configuration();
-    conf.setInt(YarnConfiguration.CLIENT_FAILOVER_RETRIES, maxRetries);
     RetryPolicy policy = FederationStateStoreFacade.createRetryPolicy(conf);
     RetryAction action = policy
         .shouldRetry(new FederationStateStoreException("Error"), 0, 0, false);
@@ -94,8 +94,6 @@ public class TestFederationStateStoreFacadeRetry {
    */
   @Test
   public void testFacadeInvalidInputException() throws Exception {
-    conf = new Configuration();
-    conf.setInt(YarnConfiguration.CLIENT_FAILOVER_RETRIES, maxRetries);
     RetryPolicy policy = FederationStateStoreFacade.createRetryPolicy(conf);
     RetryAction action = policy.shouldRetry(
         new FederationStateStoreInvalidInputException(""), 0, 0, false);
@@ -107,8 +105,6 @@ public class TestFederationStateStoreFacadeRetry {
    */
   @Test
   public void testFacadeCacheRetriableException() throws Exception {
-    conf = new Configuration();
-    conf.setInt(YarnConfiguration.CLIENT_FAILOVER_RETRIES, maxRetries);
     RetryPolicy policy = FederationStateStoreFacade.createRetryPolicy(conf);
     RetryAction action =
         policy.shouldRetry(new CacheLoaderException(""), 0, 0, false);
@@ -128,8 +124,6 @@ public class TestFederationStateStoreFacadeRetry {
   @Test
   public void testFacadePoolInitRetriableException() throws Exception {
     // PoolInitializationException is a retriable exception
-    conf = new Configuration();
-    conf.setInt(YarnConfiguration.CLIENT_FAILOVER_RETRIES, maxRetries);
     RetryPolicy policy = FederationStateStoreFacade.createRetryPolicy(conf);
     RetryAction action = policy.shouldRetry(
         new PoolInitializationException(new YarnException()), 0, 0, false);

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/markdown/Federation.md

@@ -129,6 +129,7 @@ AMRMProxy, Global Policy Generator (GPG) and Router work together to make this h
 
 
 The figure shows a sequence diagram for the following job execution flow:
+
 1. The Router receives an application submission request that is complaint to the YARN Application Client Protocol.
 2. The router interrogates a routing table / policy to choose the “home RM” for the job (the policy configuration is received from the state-store on heartbeat).
 3. The router queries the membership state to determine the endpoint of the home RM.
@@ -160,15 +161,50 @@ These are common configurations that should appear in the **conf/yarn-site.xml**
 | Property | Example | Description |
 |:---- |:---- |
 |`yarn.federation.enabled` | `true` | Whether federation is enabled or not |
+|`yarn.resourcemanager.cluster-id` | `<unique-subcluster-id>` | The unique subcluster identifier for this RM (same as the one used for HA). |
+
+####State-Store:
+
+Currently, we support ZooKeeper and SQL based implementations of the state-store.
+
+**Note:** The State-Store implementation must always be overwritten with one of the below.
+
+ZooKeeper: one must set the ZooKeeper settings for Hadoop:
+
+| Property | Example | Description |
+|:---- |:---- |
+|`yarn.federation.state-store.class` | `org.apache.hadoop.yarn.server.federation.store.impl.ZookeeperFederationStateStore` | The type of state-store to use. |
+|`hadoop.zk.address` | `host:port` | The address for the ZooKeeper ensemble. |
+
+SQL: one must setup the following parameters:
+
+| Property | Example | Description |
+|:---- |:---- |
 |`yarn.federation.state-store.class` | `org.apache.hadoop.yarn.server.federation.store.impl.SQLFederationStateStore` | The type of state-store to use. |
 |`yarn.federation.state-store.sql.url` | `jdbc:mysql://<host>:<port>/FederationStateStore` | For SQLFederationStateStore the name of the DB where the state is stored. |
 |`yarn.federation.state-store.sql.jdbc-class` | `com.mysql.jdbc.jdbc2.optional.MysqlDataSource` | For SQLFederationStateStore the jdbc class to use. |
 |`yarn.federation.state-store.sql.username` | `<dbuser>` | For SQLFederationStateStore the username for the DB connection. |
 |`yarn.federation.state-store.sql.password` | `<dbpass>` | For SQLFederationStateStore the password for the DB connection. |
-|`yarn.resourcemanager.cluster-id` | `<unique-subcluster-id>` | The unique subcluster identifier for this RM (same as the one used for HA). |
 
+We provide scripts for MySQL and Microsoft SQL Server.
 
-Optional:
+For MySQL, one must download the latest jar version 5.x from [MVN Repository](https://mvnrepository.com/artifact/mysql/mysql-connector-java) and add it to the CLASSPATH.
+Then the DB schema is created by executing the following SQL scripts in the database:
+
+1. **sbin/FederationStateStore/MySQL/FederationStateStoreDatabase.sql**.
+2. **sbin/FederationStateStore/MySQL/FederationStateStoreUser.sql**.
+3. **sbin/FederationStateStore/MySQL/FederationStateStoreTables.sql**.
+4. **sbin/FederationStateStore/MySQL/FederationStateStoreStoredProcs.sql**.
+
+In the same directory we provide scripts to drop the Stored Procedures, the Tables, the User and the Database.
+
+**Note:** the FederationStateStoreUser.sql defines a default user/password for the DB that you are **highly encouraged** to set this to a proper strong password.
+
+For SQL-Server, the process is similar, but the jdbc driver is already included.
+SQL-Server scripts are located in **sbin/FederationStateStore/SQLServer/**.
+
+
+####Optional:
 
 | Property | Example | Description |
 |:---- |:---- |
@@ -236,22 +272,6 @@ Optional:
 |`yarn.federation.statestore.max-connections` | `1` | The maximum number of parallel connections from each AMRMProxy to the state-store. This value is typically lower than the router one, since we have many AMRMProxy that could burn-through many DB connections quickly. |
 |`yarn.federation.cache-ttl.secs` | `300` | The time to leave for the AMRMProxy cache. Typically larger than at the router, as the number of AMRMProxy is large, and we want to limit the load to the centralized state-store. |
 
-###State-Store:
-
-Currently, we support only SQL based implementation of state-store (ZooKeeper is in the works), i.e. either MySQL or Microsoft SQL Server.
-
-For MySQL, one must download the latest jar version 5.x from [MVN Repository](https://mvnrepository.com/artifact/mysql/mysql-connector-java) and add it to the CLASSPATH.
-Then the DB schema is created by executing the following SQL scripts in the database:
-1. **sbin/FederationStateStore/MySQL/FederationStateStoreDatabase.sql**.
-2. **sbin/FederationStateStore/MySQL/FederationStateStoreUser.sql**.
-3. **sbin/FederationStateStore/MySQL/FederationStateStoreTables.sql**.
-4. **sbin/FederationStateStore/MySQL/FederationStateStoreStoredProcs.sql**.
-In the same directory we provide scripts to drop the Stored Procedures, the Tables, the User and the Database.
-**Note:** the FederationStateStoreUser.sql defines a default user/password for the DB that you are **highly encouraged** to set this to a proper strong password.
-
-For SQL-Server, the process is similar, but the jdbc driver is already included in the pom (license allows it).
-SQL-Server scripts are located in **sbin/FederationStateStore/SQLServer/**.
-
 Running a Sample Job
 --------------------
 In order to submit jobs to a Federation cluster one must create a seperate set of configs for the client from which jobs will be submitted. In these, the **conf/yarn-site.xml** should have the following additional configurations: