Configure HMaster to reject decommissioned hosts

hbase-common/src/main/java/org/apache/hadoop/hbase/HConstants.java

@@ -1622,6 +1622,20 @@ public enum OperationStatusCode {
    */
   public final static boolean HBASE_SERVER_USEIP_ENABLED_DEFAULT = false;
 
+  /**
+   * Should the HMaster reject hosts of decommissioned RegionServers, bypassing matching their port
+   * and startcode parts of their ServerName or not? When True, the HMaster will reject a
+   * RegionServer's request to `reportForDuty` if it's hostname exists in the list of decommissioned
+   * RegionServers it maintains internally. Added in HBASE-28342.
+   */
+  public final static String REJECT_DECOMMISSIONED_HOSTS_KEY =
+    "hbase.master.reject.decommissioned.hosts";
+
+  /**
+   * Default value of {@link #REJECT_DECOMMISSIONED_HOSTS_KEY}
+   */
+  public final static boolean REJECT_DECOMMISSIONED_HOSTS_DEFAULT = false;
+
   private HConstants() {
     // Can't be instantiated with this ctor.
   }

hbase-server/src/main/java/org/apache/hadoop/hbase/master/HMaster.java

@@ -546,7 +546,6 @@ public HMaster(final Configuration conf) throws IOException {
         HConstants.DEFAULT_HBASE_MASTER_BALANCER_MAX_RIT_PERCENT);
 
       // Do we publish the status?
-
       boolean shouldPublish =
         conf.getBoolean(HConstants.STATUS_PUBLISHED, HConstants.STATUS_PUBLISHED_DEFAULT);
       Class<? extends ClusterStatusPublisher.Publisher> publisherClass =
@@ -997,7 +996,10 @@ private void finishActiveMasterInitialization() throws IOException, InterruptedE
     masterRegion = MasterRegionFactory.create(this);
     rsListStorage = new MasterRegionServerList(masterRegion, this);
 
+    // Initialize the ServerManager and register it as a configuration observer
     this.serverManager = createServerManager(this, rsListStorage);
+    this.configurationManager.registerObserver(this.serverManager);
+
     this.syncReplicationReplayWALManager = new SyncReplicationReplayWALManager(this);
     if (
       !conf.getBoolean(HBASE_SPLIT_WAL_COORDINATED_BY_ZK, DEFAULT_HBASE_SPLIT_COORDINATED_BY_ZK)

hbase-server/src/main/java/org/apache/hadoop/hbase/master/HostIsConsideredDecommissionedException.java

@@ -0,0 +1,28 @@
+/*
+ * 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.hadoop.hbase.master;
+
+import org.apache.hadoop.hbase.HBaseIOException;
+import org.apache.yetus.audience.InterfaceAudience;
+
+@InterfaceAudience.Private
+public class HostIsConsideredDecommissionedException extends HBaseIOException {
+  public HostIsConsideredDecommissionedException(String message) {
+    super(message);
+  }
+}

hbase-server/src/main/java/org/apache/hadoop/hbase/master/ServerManager.java

@@ -28,6 +28,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
+import java.util.Objects;
 import java.util.Set;
 import java.util.concurrent.ConcurrentNavigableMap;
 import java.util.concurrent.ConcurrentSkipListMap;
@@ -51,6 +52,7 @@
 import org.apache.hadoop.hbase.client.AsyncClusterConnection;
 import org.apache.hadoop.hbase.client.AsyncRegionServerAdmin;
 import org.apache.hadoop.hbase.client.RegionInfo;
+import org.apache.hadoop.hbase.conf.ConfigurationObserver;
 import org.apache.hadoop.hbase.ipc.RemoteWithExtrasException;
 import org.apache.hadoop.hbase.master.assignment.RegionStates;
 import org.apache.hadoop.hbase.master.procedure.ServerCrashProcedure;
@@ -100,7 +102,7 @@
  * only after the handler is fully enabled and has completed the handling.
  */
 @InterfaceAudience.Private
-public class ServerManager {
+public class ServerManager implements ConfigurationObserver {
   public static final String WAIT_ON_REGIONSERVERS_MAXTOSTART =
     "hbase.master.wait.on.regionservers.maxtostart";
 
@@ -172,6 +174,9 @@ public class ServerManager {
   /** Listeners that are called on server events. */
   private List<ServerListener> listeners = new CopyOnWriteArrayList<>();
 
+  /** Configured value of HConstants.REJECT_DECOMMISSIONED_HOSTS_KEY */
+  private volatile boolean rejectDecommissionedHostsConfig;
+
   /**
    * Constructor.
    */
@@ -183,6 +188,35 @@ public ServerManager(final MasterServices master, RegionServerList storage) {
     warningSkew = c.getLong("hbase.master.warningclockskew", 10000);
     persistFlushedSequenceId =
       c.getBoolean(PERSIST_FLUSHEDSEQUENCEID, PERSIST_FLUSHEDSEQUENCEID_DEFAULT);
+    rejectDecommissionedHostsConfig = getRejectDecommissionedHostsConfig(c);
+  }
+
+  /**
+   * Implementation of the ConfigurationObserver interface. We are interested in live-loading the
+   * configuration value of HConstants.REJECT_DECOMMISSIONED_HOSTS_KEY
+   * @param conf Server configuration instance
+   */
+  @Override
+  public void onConfigurationChange(Configuration conf) {
+    final boolean newValue = getRejectDecommissionedHostsConfig(conf);
+    if (rejectDecommissionedHostsConfig == newValue) {
+      // no-op
+      return;
+    }
+
+    LOG.info("Config Reload for RejectDecommissionedHosts. previous value: {}, new value: {}",
+      rejectDecommissionedHostsConfig, newValue);
+
+    rejectDecommissionedHostsConfig = newValue;
+  }
+
+  /**
+   * Reads the value of HConstants.REJECT_DECOMMISSIONED_HOSTS_KEY from the config and returns it
+   * @param conf Configuration instance of the Master
+   */
+  public boolean getRejectDecommissionedHostsConfig(Configuration conf) {
+    return conf.getBoolean(HConstants.REJECT_DECOMMISSIONED_HOSTS_KEY,
+      HConstants.REJECT_DECOMMISSIONED_HOSTS_DEFAULT);
   }
 
   /**
@@ -227,11 +261,14 @@ ServerName regionServerStartup(RegionServerStartupRequest request, int versionNu
     final String hostname =
       request.hasUseThisHostnameInstead() ? request.getUseThisHostnameInstead() : isaHostName;
     ServerName sn = ServerName.valueOf(hostname, request.getPort(), request.getServerStartCode());
+
+    // Check if the host should be rejected based on it's decommissioned status
+    checkRejectableDecommissionedStatus(sn);
+
     checkClockSkew(sn, request.getServerCurrentTime());
     checkIsDead(sn, "STARTUP");
     if (!checkAndRecordNewServer(sn, ServerMetricsBuilder.of(sn, versionNumber, version))) {
-      LOG.warn(
-        "THIS SHOULD NOT HAPPEN, RegionServerStartup" + " could not record the server: " + sn);
+      LOG.warn("THIS SHOULD NOT HAPPEN, RegionServerStartup could not record the server: {}", sn);
     }
     storage.started(sn);
     return sn;
@@ -293,6 +330,36 @@ public void regionServerReport(ServerName sn, ServerMetrics sl) throws YouAreDea
     updateLastFlushedSequenceIds(sn, sl);
   }
 
+  /**
+   * Checks if the Master is configured to reject decommissioned hosts or not. When it's configured
+   * to do so, any RegionServer trying to join the cluster will have it's host checked against the
+   * list of hosts of currently decommissioned servers and potentially get prevented from reporting
+   * for duty; otherwise, we do nothing and we let them pass to the next check. See HBASE-28342 for
+   * details.
+   * @param sn The ServerName to check for
+   * @throws HostIsConsideredDecommissionedException if the Master is configured to reject
+   *                                                 decommissioned hosts and this host exists in
+   *                                                 the list of the decommissioned servers
+   */
+  private void checkRejectableDecommissionedStatus(ServerName sn)
+    throws HostIsConsideredDecommissionedException {
+    // If the Master is not configured to reject decommissioned hosts, return early.
+    if (!rejectDecommissionedHostsConfig) {
+      return;
+    }
+
+    // Look for a match for the hostname in the list of decommissioned servers
+    for (ServerName server : getDrainingServersList()) {
+      if (Objects.equals(server.getHostname(), sn.getHostname())) {
+        // Found a match and master is configured to reject decommissioned hosts, throw exception!
+        LOG.warn("Rejecting RegionServer {} from reporting for duty because Master is configured "
+          + "to reject decommissioned hosts and this host was marked as such in the past.", sn);
+        throw new HostIsConsideredDecommissionedException(
+          "Master is configured to reject decommissioned hosts");
+      }
+    }
+  }
+
   /**
    * Check is a server of same host and port already exists, if not, or the existed one got a
    * smaller start code, record it.

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java

@@ -120,6 +120,7 @@
 import org.apache.hadoop.hbase.ipc.ServerNotRunningYetException;
 import org.apache.hadoop.hbase.ipc.ServerRpcController;
 import org.apache.hadoop.hbase.log.HBaseMarkers;
+import org.apache.hadoop.hbase.master.HostIsConsideredDecommissionedException;
 import org.apache.hadoop.hbase.mob.MobFileCache;
 import org.apache.hadoop.hbase.mob.RSMobFileCleanerChore;
 import org.apache.hadoop.hbase.monitoring.TaskMonitor;
@@ -2664,6 +2665,11 @@ private RegionServerStartupResponse reportForDuty() throws IOException {
         LOG.error(HBaseMarkers.FATAL, "Master rejected startup because clock is out of sync", ioe);
         // Re-throw IOE will cause RS to abort
         throw ioe;
+      } else if (ioe instanceof HostIsConsideredDecommissionedException) {
+        LOG.error(HBaseMarkers.FATAL,
+          "Master rejected startup because the host is considered decommissioned", ioe);
+        // Re-throw IOE will cause RS to abort
+        throw ioe;
       } else if (ioe instanceof ServerNotRunningYetException) {
         LOG.debug("Master is not running yet");
       } else {

hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestRegionServerReportForDuty.java

@@ -22,6 +22,8 @@
 
 import java.io.IOException;
 import java.io.StringWriter;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.concurrent.ScheduledThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
 import org.apache.commons.lang3.StringUtils;
@@ -241,6 +243,136 @@ public void run() {
     waitForClusterOnline(master);
   }
 
+  /**
+   * Tests that the RegionServer's reportForDuty gets rejected by the master when the master is
+   * configured to reject decommissioned hosts and when there is a match for the joining
+   * RegionServer in the list of decommissioned servers. Test case for HBASE-28342.
+   */
+  @Test
+  public void testReportForDutyGetsRejectedByMasterWhenConfiguredToRejectDecommissionedHosts()
+    throws Exception {
+    // Start a master and wait for it to become the active/primary master.
+    // Use a random unique port
+    cluster.getConfiguration().setInt(HConstants.MASTER_PORT, HBaseTestingUtil.randomFreePort());
+    cluster.getConfiguration().setInt(ServerManager.WAIT_ON_REGIONSERVERS_MINTOSTART, 1);
+    cluster.getConfiguration().setInt(ServerManager.WAIT_ON_REGIONSERVERS_MAXTOSTART, 1);
+
+    // Set the cluster to reject decommissioned hosts
+    cluster.getConfiguration().setBoolean(HConstants.REJECT_DECOMMISSIONED_HOSTS_KEY, true);
+
+    master = cluster.addMaster();
+    rs = cluster.addRegionServer();
+    LOG.debug("Starting master: " + master.getMaster().getServerName());
+    master.start();
+    rs.start();
+    waitForClusterOnline(master);
+
+    assertEquals(0, master.getMaster().listDecommissionedRegionServers().size());
+    assertEquals(0, master.getMaster().getServerManager().getDrainingServersList().size());
+    assertEquals(1, master.getMaster().getServerManager().getOnlineServers().size());
+
+    // Decommission the region server and tries to re-add it
+    List<ServerName> serversToDecommission = new ArrayList<ServerName>();
+    serversToDecommission.add(rs.getRegionServer().getServerName());
+    master.getMaster().decommissionRegionServers(serversToDecommission, true);
+
+    // Assert that the server is now decommissioned
+    ServerName decommissionedServer = master.getMaster().listDecommissionedRegionServers().get(0);
+    assertEquals(1, master.getMaster().listDecommissionedRegionServers().size());
+    assertEquals(1, master.getMaster().getServerManager().getDrainingServersList().size());
+    assertEquals(1, master.getMaster().getServerManager().getOnlineServers().size());
+    assertEquals(rs.getRegionServer().getServerName().toString(),
+      decommissionedServer.getServerName());
+
+    // Create a second region server
+    cluster.getConfiguration().set(HConstants.REGION_SERVER_IMPL, MyRegionServer.class.getName());
+    rs2 = cluster.addRegionServer();
+    rs2.start();
+    waitForSecondRsStarted();
+
+    // Assert that the number of decommissioned and live hosts didn't change and that the hostname
+    // of rs2 matches that of the decommissioned server
+    String rs2HostName = rs2.getRegionServer().getServerName().getHostname();
+    assertEquals(1, master.getMaster().listDecommissionedRegionServers().size());
+    assertEquals(1, master.getMaster().getServerManager().getDrainingServersList().size());
+    assertEquals(1, master.getMaster().getServerManager().getOnlineServers().size());
+    assertEquals(rs2HostName, decommissionedServer.getHostname());
+  }
+
+  /**
+   * Tests that the RegionServer's reportForDuty gets accepted by the master when the master is not
+   * configured to reject decommissioned hosts, even when there is a match for the joining
+   * RegionServer in the list of decommissioned servers. Test case for HBASE-28342.
+   */
+  @Test
+  public void testReportForDutyGetsAcceptedByMasterWhenNotConfiguredToRejectDecommissionedHosts()
+    throws Exception {
+    // Start a master and wait for it to become the active/primary master.
+    // Use a random unique port
+    cluster.getConfiguration().setInt(HConstants.MASTER_PORT, HBaseTestingUtil.randomFreePort());
+    cluster.getConfiguration().setInt(ServerManager.WAIT_ON_REGIONSERVERS_MINTOSTART, 1);
+    cluster.getConfiguration().setInt(ServerManager.WAIT_ON_REGIONSERVERS_MAXTOSTART, 1);
+
+    // Set the cluster to not reject decommissioned hosts (default behavior)
+    cluster.getConfiguration().setBoolean(HConstants.REJECT_DECOMMISSIONED_HOSTS_KEY, false);
+
+    master = cluster.addMaster();
+    rs = cluster.addRegionServer();
+    LOG.debug("Starting master: " + master.getMaster().getServerName());
+    master.start();
+    rs.start();
+    waitForClusterOnline(master);
+
+    assertEquals(0, master.getMaster().listDecommissionedRegionServers().size());
+    assertEquals(0, master.getMaster().getServerManager().getDrainingServersList().size());
+    assertEquals(1, master.getMaster().getServerManager().getOnlineServers().size());
+
+    // Decommission the region server and tries to re-add it
+    List<ServerName> serversToDecommission = new ArrayList<>();
+    serversToDecommission.add(rs.getRegionServer().getServerName());
+    master.getMaster().decommissionRegionServers(serversToDecommission, true);
+
+    // Assert that the server is now decommissioned
+    ServerName decommissionedServer = master.getMaster().listDecommissionedRegionServers().get(0);
+    assertEquals(1, master.getMaster().listDecommissionedRegionServers().size());
+    assertEquals(1, master.getMaster().getServerManager().getDrainingServersList().size());
+    assertEquals(1, master.getMaster().getServerManager().getOnlineServers().size());
+    assertEquals(rs.getRegionServer().getServerName().toString(),
+      decommissionedServer.getServerName());
+
+    // Create a second region server and try adding both region servers to it, it should succeed
+    cluster.getConfiguration().set(HConstants.REGION_SERVER_IMPL, MyRegionServer.class.getName());
+    rs2 = cluster.addRegionServer();
+    rs2.start();
+    waitForSecondRsStarted();
+
+    master.getMaster().stop("Stopping master");
+
+    // Start a new master and use another random unique port
+    // Also let it wait for exactly 2 region severs to report in
+    cluster.getConfiguration().setInt(HConstants.MASTER_PORT, HBaseTestingUtil.randomFreePort());
+    cluster.getConfiguration().setInt(ServerManager.WAIT_ON_REGIONSERVERS_MINTOSTART, 2);
+    cluster.getConfiguration().setInt(ServerManager.WAIT_ON_REGIONSERVERS_MAXTOSTART, 2);
+    backupMaster = cluster.addMaster();
+    LOG.debug("Starting new master: " + backupMaster.getMaster().getServerName());
+    backupMaster.start();
+
+    waitForClusterOnline(backupMaster);
+
+    // Assert that the backup master has become active.
+    assertTrue(backupMaster.getMaster().isActiveMaster());
+    assertTrue(backupMaster.getMaster().isInitialized());
+
+    // Assert that the number of decommissioned hosts is the same and that the live and online hosts
+    // did in fact change and rs2 is now part of the cluster even though there is a match for its
+    // hostname in the list of decommissioned servers
+    String rs2HostName = rs2.getRegionServer().getServerName().getHostname();
+    assertEquals(1, backupMaster.getMaster().listDecommissionedRegionServers().size());
+    assertEquals(1, backupMaster.getMaster().getServerManager().getDrainingServersList().size());
+    assertEquals(2, backupMaster.getMaster().getServerManager().getOnlineServers().size());
+    assertEquals(rs2HostName, decommissionedServer.getHostname());
+  }
+
   /**
    * Tests region sever reportForDuty with a non-default environment edge
    */