Details

    • Type: Bug
    • Status: Resolved
    • Priority: Blocker
    • Resolution: Fixed
    • Affects Version/s: 3.5.0, 3.5.1, 3.5.3
    • Fix Version/s: 3.5.4, 3.6.0
    • Component/s: server
    • Labels:
      None

      Description

      ZOOKEEPER-1506 fixed a DNS resolution issue in 3.4. Some portions of the fix haven't yet been ported to 3.5.

      To recap the outstanding problem in 3.5, if a given ZK server is started before all peer addresses are resolvable, that server may cache a negative lookup result and forever fail to resolve the address. For example, deploying ZK 3.5 to Kubernetes using a StatefulSet plus a Service (headless) may fail because the DNS records are created lazily.

      2018-02-18 09:11:22,583 [myid:0] - WARN  [QuorumPeer[myid=0](plain=/0:0:0:0:0:0:0:0:2181)(secure=disabled):Follower@95] - Exception when following the leader
      java.net.UnknownHostException: zk-2.zk.default.svc.cluster.local
              at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:184)
              at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
              at java.net.Socket.connect(Socket.java:589)
              at org.apache.zookeeper.server.quorum.Learner.sockConnect(Learner.java:227)
              at org.apache.zookeeper.server.quorum.Learner.connectToLeader(Learner.java:256)
              at org.apache.zookeeper.server.quorum.Follower.followLeader(Follower.java:76)
              at org.apache.zookeeper.server.quorum.QuorumPeer.run(QuorumPeer.java:1133)
      

      In the above example, the address `zk-2.zk.default.svc.cluster.local` was not resolvable when the server started, but became resolvable shortly thereafter. The server should eventually succeed but doesn't.

        Attachments

        1. 3.5.3-beta.zip
          17 kB
          Eron Wright
        2. fixed.log
          59 kB
          Eron Wright

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              • Assignee:
                fpj Flavio Junqueira
                Reporter:
                eronwright Eron Wright
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                • Created:
                  Updated:
                  Resolved: