安装 Zookeeper 启动报错

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Error contacting service. It is probably not running.

• 记录在安装启动Zookeeper 3.6.1 时遇到的问题与解决方法

环境信息:

CentOS Linux release 7.8.2003

java version “1.8.0_161”

apache-zookeeper-3.6.1-bin.tar.gz

• 安装过程

  tar -zxvf /opt/apache-zookeeper-3.6.1-bin.tar.gz -C ./
  mv apache-zookeeper-3.6.1-bin zookeeper-3.6.1
  cd zookeeper-3.6.1
  " 创建 dataDir, 在 zoo.cfg 中修改 dataDir"
  mkdir data
  cd zookeeper-3.6.1/conf
  cp zoo_sample.cfg zoo.cfg
  vim zoo.cfg
  " 修改 dataDir 为上面创建的 data 目录"
  

  • 至此, 安装结束, 进行启动

  [zookeeper-3.6.1]# ./bin/zkServer.sh start
  ZooKeeper JMX enabled by default
  Using config: /usr/local/zookeeper/zookeeper-3.6.1/bin/../conf/zoo.cfg
  Starting zookeeper ... STARTED
  

  • 启动正常, 查看状态

  [zookeeper-3.6.1]# ./bin/zkServer.sh status
  ZooKeeper JMX enabled by default
  Using config: /usr/local/zookeeper/zookeeper-3.6.1/bin/../conf/zoo.cfg
  Client port found: 2181. Client address: localhost.
  Error contacting service. It is probably not running
  

  • 查看状态错误, 使用 ps 命令和 netstat 命令查看2181端口均没有显示, 说明启动失败

  查阅相关资料后, 解释的原因有下面几种:

  1. 没有创建dataDir目录
  2. 没有关闭防火墙
  3. 2181端口被占用
  4. zoo.cfg文件中主机名出错
  5. myid文件中的整数格式不对，或者与zoo.cfg中的server整数不对应

• 经过排查上述原因, 均为解决

解决方法

• 最终发现, 直接查看日志文件即可

  查看位于zookeeper-3.6.1/logs下的.out文件

  [myid:] - ERROR [main:ZooKeeperServerMain@85] - Unable to start AdminServer, exiting abnormally                
  org.apache.zookeeper.server.admin.AdminServer$AdminServerException: Problem starting AdminServer on address 0.0.0.0, port 8080 and comm
  and URL /commands
      at org.apache.zookeeper.server.admin.JettyAdminServer.start(JettyAdminServer.java:176)
      at org.apache.zookeeper.server.ZooKeeperServerMain.runFromConfig(ZooKeeperServerMain.java:153)
      at org.apache.zookeeper.server.ZooKeeperServerMain.initializeAndRun(ZooKeeperServerMain.java:112)
      at org.apache.zookeeper.server.ZooKeeperServerMain.main(ZooKeeperServerMain.java:67)
      at org.apache.zookeeper.server.quorum.QuorumPeerMain.initializeAndRun(QuorumPeerMain.java:140)
      at org.apache.zookeeper.server.quorum.QuorumPeerMain.main(QuorumPeerMain.java:90)
  Caused by: java.io.IOException: Failed to bind to /0.0.0.0:8080
      at org.eclipse.jetty.server.ServerConnector.openAcceptChannel(ServerConnector.java:346)
      at org.eclipse.jetty.server.ServerConnector.open(ServerConnector.java:307)
      at org.eclipse.jetty.server.AbstractNetworkConnector.doStart(AbstractNetworkConnector.java:80)
      at org.eclipse.jetty.server.ServerConnector.doStart(ServerConnector.java:231)
      at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:72)
      at org.eclipse.jetty.server.Server.doStart(Server.java:385)
      at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:72)
      at org.apache.zookeeper.server.admin.JettyAdminServer.start(JettyAdminServer.java:167)
      ... 5 more
  Caused by: java.net.BindException: 地址已在使用
      at sun.nio.ch.Net.bind0(Native Method)
      at sun.nio.ch.Net.bind(Net.java:433)
      at sun.nio.ch.Net.bind(Net.java:425)
      at sun.nio.ch.ServerSocketChannelImpl.bind(ServerSocketChannelImpl.java:223)
      at sun.nio.ch.ServerSocketAdaptor.bind(ServerSocketAdaptor.java:74)
      at org.eclipse.jetty.server.ServerConnector.openAcceptChannel(ServerConnector.java:342)
      ... 12 more
  Unable to start AdminServer, exiting abnormally
  

  • 显而易见, 是因为8080端口被占用, 解决端口占用后, 即可正常启动

  ZooKeeper JMX enabled by default
  Using config: /usr/local/zookeeper/zookeeper-3.6.1/bin/../conf/zoo.cfg
  Client port found: 2181. Client address: localhost.
  Mode: standalone
  

总结

以后出现问题, 不要忙着百度, 看看日志文件, 就可以解决大部分问题, 如果不行再百度