Zookeeper深入理解（一）搭建与测试
Zookeeper 分布式服务框架是 Apache Hadoop 的一个子项目，它主要是用来解决分布式应用中经常遇到的一些数据管理问题，如：统一命名服务、状态同步服务、集群管理、分布式应用配置项的管理等。现在openstack的项目已经有开始使用zookeeper来实现分布式开发，例如Ceilometer的Central Agent。在SDN控制器开发领域，对于控制器的高可用和负载均衡的需求也需要引用zookeeper工具。因此作为openstack架构师和开发人员，有必要深入研究zookeeper的原理和开发技巧。由于zookeeper是基于java开发项目，作为openstack的python开发语言，现在已经有一些成熟的接口api和项目，例如kazoo、tooz等。
首先我们要搭建一套zookeeper的学习研究环境
单机搭建见
http://www.cnblogs.com/liujianzuo888/articles/6088655.html
1.获取zookeeper包 wget http://mirror.nus.edu.sg/apache/zookeeper/zookeeper-3.4.6/zookeeper-3.4.6.tar.gz 2.创建三节点环境 server1 ├── data ├── dataLog ├── logs ├── zookeeper-3.4.6 └── zookeeper-3.4.6.tar.gz server2 ├── data ├── dataLog ├── logs ├── zookeeper-3.4.6 └── zookeeper-3.4.6.tar.gz server3 ├── data ├── dataLog ├── logs ├── zookeeper-3.4.6 └── zookeeper-3.4.6.tar.gz Server主配置zoo.cfg # 心跳间隔时间(ms) tickTime=2000 # Follower与Leader初始化时能容忍的时间(initLimit * tickTime) initLimit=10 # Follower与Leader请求响应时能容忍的时间(syncLimit * tickTime) syncLimit=5 # server1数据目录，每个server各自配置 dataDir=/path/to/server1/data # 客户端连接端口 clientPort=2182 # server列表: # # .n(标记server)=(server地址):(投票时所用端口):(选举Leader时所用端口) server.1=127.0.0.1:2889:3889 server.2=127.0.0.1:2990:3990 server.3=127.0.0.1:2991:3991 在每个Server/data目录下建立一个myid文件，标识自己是哪个Server(对应zoo.cfg的server列表) 现在启动server1 server1/zookeeper-3.4.6/bin/zkServer.sh start-foreground # # 输出 2015-03-02 19:56:47,485 [myid:1] - INFO [QuorumPeer[myid=1]/0:0:0:0:0:0:0:0:2182:QuorumPeer@714] - LOOKING 2015-03-02 19:56:47,486 [myid:1] - INFO [QuorumPeer[myid=1]/0:0:0:0:0:0:0:0:2182:FastLeaderElection@815] - New election. My id = 1, proposed zxid=0x1a00000006 2015-03-02 19:56:47,488 [myid:1] - INFO [WorkerReceiver[myid=1]:FastLeaderElection@597] - Notification: 1 (message format version), 1 (n.leader), 0x1a00000006 (n.zxid), 0x1 (n.round), LOOKING (n.state), 1 (n.sid), 0x1a (n.peerEpoch) LOOKING (my state) 2015-03-02 19:56:47,510 [myid:1] - WARN [WorkerSender[myid=1]:QuorumCnxManager@382] - Cannot open channel to 2 at election address /127.0.0.1:3990 java.net.ConnectException: Connection refused at java.net.PlainSocketImpl.socketConnect(Native Method) at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:345) at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206) at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188) at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392) at java.net.Socket.connect(Socket.java:589) at org.apache.zookeeper.server.quorum.QuorumCnxManager.connectOne(QuorumCnxManager.java:368) at org.apache.zookeeper.server.quorum.QuorumCnxManager.toSend(QuorumCnxManager.java:341) at org.apache.zookeeper.server.quorum.FastLeaderElection$Messenger$WorkerSender.process(FastLeaderElection.java:449) at org.apache.zookeeper.server.quorum.FastLeaderElection$Messenger$WorkerSender.run(FastLeaderElection.java:430) at java.lang.Thread.run(Thread.java:744) 2015-03-02 19:56:47,560 [myid:1] - WARN [WorkerSender[myid=1]:QuorumCnxManager@382] - Cannot open channel to 3 at election address /127.0.0.1:3991 server1尝试连接zoo.cfg中配置的server列表，这时server2，server3还没启动，因此连接失败， 将server2，server3一并启动后，可以看到server1已经成为Follower 2015-03-02 20:02:41,487 [myid:1] - INFO [/127.0.0.1:3889:QuorumCnxManager$Listener@511] - Received connection request /127.0.0.1:65469 2015-03-02 20:02:41,492 [myid:1] - INFO [WorkerReceiver[myid=1]:FastLeaderElection@597] - Notification: 1 (message format version), 3 (n.leader), 0x1a00000006 (n.zxid)0x1 (n.round), LOOKING (n.state), 3 (n.sid), 0x1a (n.peerEpoch) FOLLOWING (my state) 于是，可以使用客户端尝试连接这个集群，并且客户端会被随机分配到一个server zookeeper-3.4.6/bin/zkCli.sh -server 127.0.0.1:2182,127.0.0.1:2183,127.0.0.1:2184 3.简单测试 列出节点信息： [zk: 127.0.0.1:2182,127.0.0.1:2183,127.0.0.1:2184(CONNECTED) 11] ls / [dubbo, zookeeper, pampas, pubsub] 创建/workers节点： [zk: 127.0.0.1:2182,127.0.0.1:2183,127.0.0.1:2184(CONNECTED) 11] create /workers "" [zk: 127.0.0.1:2182,127.0.0.1:2183,127.0.0.1:2184(CONNECTED) 11] ls / [dubbo, zookeeper, workers, pampas, pubsub] 删除/workers节点： [zk: 127.0.0.1:2182,127.0.0.1:2183,127.0.0.1:2184(CONNECTED) 11] delete /workers [zk: localhost:2181(CONNECTED) 4] ls / [zk: 127.0.0.1:2182,127.0.0.1:2183,127.0.0.1:2184(CONNECTED) 11] [zk: localhost:2181(CONNECTED) 5] quit 通过以上步骤，我们就成功搭建出一套三节点zookeeper伪集群环境，为后面原理验证和python接口开发打好基础。
