[GitHub] [helix] pkuwm commented on a change in pull request #861: Make ClusterSetup realm-aware

[GitBox <gi...@apache.org>]

pkuwm commented on a change in pull request #861: Make ClusterSetup realm-aware
URL: https://github.com/apache/helix/pull/861#discussion_r388709568
 
 

 ##########
 File path: helix-core/src/main/java/org/apache/helix/tools/ClusterSetup.java
 ##########
 @@ -135,37 +138,74 @@
   public static final String removeConstraint = "removeConstraint";
 
   private static final Logger _logger = LoggerFactory.getLogger(ClusterSetup.class);
-  private final String _zkServerAddress;
-  private final HelixZkClient _zkClient;
-  // true if ZkBaseDataAccessor was instantiated with a HelixZkClient, false otherwise
+  private String _zkServerAddress;
+  private final RealmAwareZkClient _zkClient;
+  // true if ZkBaseDataAccessor was instantiated with a RealmAwareZkClient, false otherwise
   // This is used for close() to determine how ZkBaseDataAccessor should close the underlying
   // ZkClient
   private final boolean _usesExternalZkClient;
   private final HelixAdmin _admin;
 
   public ClusterSetup(String zkServerAddress) {
     _zkServerAddress = zkServerAddress;
-    _zkClient = SharedZkClientFactory.getInstance()
-        .buildZkClient(new HelixZkClient.ZkConnectionConfig(_zkServerAddress));
-    _zkClient.setZkSerializer(new ZNRecordSerializer());
+
+    // First, try to start on multi-realm mode using FederatedZkClient
+    RealmAwareZkClient zkClient;
+    try {
+      zkClient = new FederatedZkClient(
+          new RealmAwareZkClient.RealmAwareZkConnectionConfig.Builder().build(),
+          new RealmAwareZkClient.RealmAwareZkClientConfig());
+    } catch (InvalidRoutingDataException | IOException | IllegalStateException e) {
+      // Note: IllegalStateException is for HttpRoutingDataReader if MSDS endpoint cannot be found
+      // Fall back to single-realm mode using SharedZkClient (HelixZkClient)
+      // This is to preserve backward-compatibility
+      if (zkServerAddress == null || zkServerAddress.isEmpty()) {
+        throw new IllegalArgumentException("ZK server address is null or empty!");
+      }
+      zkClient = SharedZkClientFactory.getInstance()
+          .buildZkClient(new HelixZkClient.ZkConnectionConfig(_zkServerAddress));
+      zkClient.setZkSerializer(new ZNRecordSerializer());
+    }
+
+    _zkClient = zkClient;
     _admin = new ZKHelixAdmin(_zkClient);
     _usesExternalZkClient = false;
   }
 
-  public ClusterSetup(HelixZkClient zkClient) {
+  public ClusterSetup(RealmAwareZkClient zkClient) {
     _zkServerAddress = zkClient.getServers();
     _zkClient = zkClient;
     _admin = new ZKHelixAdmin(_zkClient);
     _usesExternalZkClient = true;
   }
 
-  public ClusterSetup(HelixZkClient zkClient, HelixAdmin zkHelixAdmin) {
+  public ClusterSetup(RealmAwareZkClient zkClient, HelixAdmin zkHelixAdmin) {
     _zkServerAddress = zkClient.getServers();
     _zkClient = zkClient;
     _admin = zkHelixAdmin;
     _usesExternalZkClient = true;
   }
 
+  private ClusterSetup(Builder builder) throws IOException, InvalidRoutingDataException {
 
 Review comment:
   Like you mentioned, do we need the checked exception signature? If yes, what is the consideration to have it thrown checked exceptions?

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