使用 Apache Curator 时，为什么创建 zNode 会导致 NoNodeException

Question

我正在尝试像这样在 Zookeeper 中创建一个“目录”：

curatorFramework = CuratorFrameworkFactory.newClient(
    "ip-111-11-111-1.us-west-2.compute.internal/111.11.111.1:2181",
    zkInfo.getSessionTimeoutMs(),
    zkInfo.getConnectionTimeoutMs(),
    new RetryNTimes(zkInfo.getRetryAttempts(), 
    zkInfo.getRetryIntervalMs())
);
curatorFramework.start();

byte[] byteArray = new byte[1];
byteArray[0] = (byte) 7;

curatorFramework.create()
    .withMode(CreateMode.PERSISTENT)
    .withACL(ZooDefs.Ids.OPEN_ACL_UNSAFE)
    .forPath("/my_node", byteArray); 

令人困惑的是，它在我尝试创建的节点上给了我一个“NoNodeException”。

Caused by: org.apache.zookeeper.KeeperException$NoNodeException: KeeperErrorCode = NoNode for /my_node
        at org.apache.zookeeper.KeeperException.create(KeeperException.java:111) ~[stormjar.jar:?]
        at org.apache.zookeeper.KeeperException.create(KeeperException.java:51) ~[stormjar.jar:?]
        at org.apache.zookeeper.ZooKeeper.create(ZooKeeper.java:783) ~[stormjar.jar:?]
        at org.apache.curator.framework.imps.CreateBuilderImpl$17.call(CreateBuilderImpl.java:1176) ~[stormjar.jar:?]
        at org.apache.curator.framework.imps.CreateBuilderImpl$17.call(CreateBuilderImpl.java:1156) ~[stormjar.jar:?]
        at org.apache.curator.connection.StandardConnectionHandlingPolicy.callWithRetry(StandardConnectionHandlingPolicy.java:64) ~[stormjar.jar:?]
        at org.apache.curator.RetryLoop.callWithRetry(RetryLoop.java:100) ~[stormjar.jar:?]
        at org.apache.curator.framework.imps.CreateBuilderImpl.pathInForeground(CreateBuilderImpl.java:1153) ~[stormjar.jar:?]
        at org.apache.curator.framework.imps.CreateBuilderImpl.protectedPathInForeground(CreateBuilderImpl.java:607) ~[stormjar.jar:?]
        at org.apache.curator.framework.imps.CreateBuilderImpl.forPath(CreateBuilderImpl.java:597) ~[stormjar.jar:?]
        at org.apache.curator.framework.imps.CreateBuilderImpl$3.forPath(CreateBuilderImpl.java:362) ~[stormjar.jar:?]
        at org.apache.curator.framework.imps.CreateBuilderImpl$3.forPath(CreateBuilderImpl.java:310) ~[stormjar.jar:?]

请注意，我可以连接到 Zookeeper：

Socket connection established to ip-111-11-111-1.us-west-2.compute.internal/111.11.111.1:2181, initiating session
Session establishment complete on server ip-111-11-111-1.us-west-2.compute.internal/111.11.111.1:2181, sessionid = 0x100000363b13354, negotiated timeout = 20000        

请注意，Zookeeper 服务器位于远程机器上，并且该帖子中的 ip ("111.11.111.1") 已更改。

Answer 1

于是我尝试用 zkCli 连接，发现问题出在我的 connectString 上：

/opt/zookeeper-3.6.1/bin/zkCli.sh -server ip-111-11-111-1.us-west-2.compute.internal/111.11.111.1:2181
Welcome to ZooKeeper!
[myid:ip-111-11-111-1.us-west-2.compute.internal:2181] - INFO  [main-SendThread(ip-111-11-111-1.us-west-2.compute.internal:2181):ClientCnxn$SendThread@1154] - Opening socket connection to server ip-111-11-111-1.us-west-2.compute.internal/111.11.111.1:2181.
[myid:ip-111-11-111-1.us-west-2.compute.internal:2181] - INFO  [main-SendThread(ip-111-11-111-1.us-west-2.compute.internal:2181):ClientCnxn$SendThread@986] - Socket connection established, initiating session, client: /111.11.111.2:43736, server: ip-111-11-111-1.us-west-2.compute.internal/111.11.111.1:2181
[myid:ip-111-11-111-1.us-west-2.compute.internal:2181] - INFO  [main-SendThread(ip-111-11-111-1.us-west-2.compute.internal:2181):ClientCnxn$SendThread@1420] - Session establishment complete on server ip-111-11-111-1.us-west-2.compute.internal/111.11.111.1:2181, session id = 0x100000363b1d2e8, negotiated timeout = 30000

[zk: ip-111-11-111-1.us-west-2.compute.internal/111.11.111.1:2181(CONNECTED) 0] ls /
Node does not exist: /
[zk: ip-111-11-111-1.us-west-2.compute.internal/111.11.111.1:2181(CONNECTED) 1] create /my_node
Node does not exist: /my_node

如您所见，尝试创建节点会在 zkCli 中出现 NoNode 错误。

原来ip-111-11-111-1.us-west-2.compute.internal/111.11.111.1:2181不是一个正确的连接字符串，但我很困惑，因为zkCli允许我连接到它。

Answer 2

似乎与 ACL 相关，只是为了确定，您可以手动创建它。

找到您的本地 zk 二进制文件（不需要在远程主机上）并启动指向您的服务器的客户端 (zkCli)。连接后，创建新的 znode：

bin/zkCli.sh -server 111.11.111.1:2181

[zkshell:x] create /my_node
>>Created /mynode

shell 应该输出最后一句话以保证节点已经创建。完成后，再次启动 Curator 进程。

查看here 了解有关 zk 客户端的更多详细信息。