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  1. Hadoop HDFS
  2. HDFS-13040

Kerberized inotify client fails despite kinit properly



    • Bug
    • Status: Resolved
    • Major
    • Resolution: Fixed
    • 2.6.0
    • 3.1.0, 2.10.0, 3.0.3
    • namenode
    • None
    • Kerberized, HA cluster, iNotify client, CDH5.10.2

    • Reviewed


      This issue is similar to HDFS-10799.

      HDFS-10799 turned out to be a client side issue where client is responsible for renewing kerberos ticket actively.

      However we found in a slightly setup even if client has valid Kerberos credentials, inotify still fails.

      Suppose client uses principal hdfs@EXAMPLE.COM,
      namenode 1 uses server principal hdfs/nn1.example.com@EXAMPLE.COM
      namenode 2 uses server principal hdfs/nn2.example.com@EXAMPLE.COM

      After Namenodes starts for longer than kerberos ticket lifetime, the client fails with the following error:

      18/01/19 11:23:02 WARN security.UserGroupInformation: PriviledgedActionException as:hdfs@GCE.CLOUDERA.COM (auth:KERBEROS) cause:org.apache.hadoop.ipc.RemoteException(java.io.IOException): We encountered an error reading https://nn2.example.com:8481/getJournal?jid=ns1&segmentTxId=8662&storageInfo=-60%3A353531113%3A0%3Acluster3, https://nn1.example.com:8481/getJournal?jid=ns1&segmentTxId=8662&storageInfo=-60%3A353531113%3A0%3Acluster3.  During automatic edit log failover, we noticed that all of the remaining edit log streams are shorter than the current one!  The best remaining edit log ends at transaction 8683, but we thought we could read up to transaction 8684.  If you continue, metadata will be lost forever!
              at org.apache.hadoop.hdfs.server.namenode.RedundantEditLogInputStream.nextOp(RedundantEditLogInputStream.java:213)
              at org.apache.hadoop.hdfs.server.namenode.EditLogInputStream.readOp(EditLogInputStream.java:85)
              at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.readOp(NameNodeRpcServer.java:1701)
              at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.getEditsFromTxid(NameNodeRpcServer.java:1763)
              at org.apache.hadoop.hdfs.server.namenode.AuthorizationProviderProxyClientProtocol.getEditsFromTxid(AuthorizationProviderProxyClientProtocol.java:1011)
              at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolServerSideTranslatorPB.getEditsFromTxid(ClientNamenodeProtocolServerSideTranslatorPB.java:1490)
              at org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos$ClientNamenodeProtocol$2.callBlockingMethod(ClientNamenodeProtocolProtos.java)
              at org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:617)
              at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:1073)
              at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2216)
              at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2212)
              at java.security.AccessController.doPrivileged(Native Method)
              at javax.security.auth.Subject.doAs(Subject.java:415)
              at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1920)
              at org.apache.hadoop.ipc.Server$Handler.run(Server.java:2210)

      Typically if NameNode has an expired Kerberos ticket, the error handling for the typical edit log tailing would let NameNode to relogin with its own Kerberos principal. However, when inotify uses the same code path to retrieve edits, since the current user is the inotify client's principal, unless client uses the same principal as the NameNode, NameNode can't do it on behalf of the client.

      Therefore, a more appropriate approach is to use proxy user so that NameNode can retrieving edits on behalf of the client.

      I will attach a patch to fix it. This patch has been verified to work for a CDH5.10.2 cluster, however it seems impossible to craft a unit test for this fix because the way Hadoop UGI handles Kerberos credentials (I can't have a single process that logins as two Kerberos principals simultaneously and let them establish connection)

      A possible workaround is for the inotify client to use the active NameNode's server principal. However, that's not going to work when there's a namenode failover, because then the client's principal will not be consistent with the active NN's one, and then fails to authenticate.

      Credit: this bug was confirmed and reproduced by pifta and r1pp3rj4ck


        1. HDFS-13040.branch-2.01.patch
          6 kB
          Xiao Chen
        2. HDFS-13040.07.patch
          16 kB
          Xiao Chen
        3. HDFS-13040.06.patch
          20 kB
          Xiao Chen
        4. HDFS-13040.05.patch
          20 kB
          Xiao Chen
        5. HDFS-13040.04.patch
          13 kB
          Xiao Chen
        6. HDFS-13040.03.patch
          15 kB
          Xiao Chen
        7. HDFS-13040.half.test.patch
          11 kB
          Xiao Chen
        8. HDFS-13040.02.patch
          0.9 kB
          Xiao Chen
        9. TestDFSInotifyEventInputStreamKerberized.java
          7 kB
          István Fajth
        10. TransactionReader.java
          2 kB
          Wei-Chiu Chuang
        11. HDFS-13040.001.patch
          2 kB
          Wei-Chiu Chuang

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              xiaochen Xiao Chen
              weichiu Wei-Chiu Chuang
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