zookeeper集群安装
我们首先准备三台服务器，IP地址分别如下（前提是要先安装JDK）
192.168.100.101 192.168.100.102 192.168.100.103
1、配置主机名到IP地址的映射(此步骤不是必须的,我们可以直接在zk的配置文件中填写IP地址)，这样配置的好处是如果某个IP地址发生了变化，我们不需要重启zookeeper，直接修改主机对应的IP地址即可。
直接修改/etc/hosts文件，设置主机zoo-1映射到192.168.100.101，设置主机zoo-2映射到192.168.100.102，设置主机zoo-3映射到192.168.100.103
[root@localhost zookeeper]# vi /etc/hosts
然后在文件末尾追加
192.168.100.101 zoo-1 192.168.100.102 zoo-2 192.168.100.103 zoo-3
这里的映射关系，保存后立即生效的。
2、在其中一台机器上安装zookeeper，下载zookeeper到zoo-1的机器上，此处使用的zookeeper-3.4.9，zookeeper下载解压后，修改配置文件即可使用。
[root@localhost zookeeper]# tar zxvf /usr/local/download/zookeeper-3.4.9.tar.gz /usr/local/soft/zookeeper
进入conf目录下，将zoo_sample.cfg复制一份重命名为zoo.cfg(zookeeper启动时默认寻找conf下名字为zoo.cfg的配置文件)
[root@localhost zookeeper]# cd /usr/local/soft/zookeeper/zookeeper-3.4.9/ [root@localhost conf]# cp zoo_sample.cfg zoo.cfg
修改zoo.cfg中的配置信息
[root@localhost conf]# vi zoo.cfg
修改配置文件信息如下
# The number of milliseconds of each tick tickTime=2000 # The number of ticks that the initial # synchronization phase can take initLimit=10 # The number of ticks that can pass between # sending a request and getting an acknowledgement syncLimit=5 # the directory where the snapshot is stored. # do not use /tmp for storage, /tmp here is just # example sakes. dataDir=/usr/local/data/zookeeper #zookeeper数据目录 # the port at which the clients will connect clientPort=2181 # the maximum number of client connections. # increase this if you need to handle more clients #maxClientCnxns=60 #设置集群信息,此处的zoo-x可以用ip地址代替 server.1=zoo-1:2888:3888 server.2=zoo-2:2888:3888 server.3=zoo-3:2888:3888
创建zookeeper的数据目录，即我们zoo.cfg中的dataDir对应的目录
[root@localhost conf]# mkdir /usr/local/data/zookeeper
在dataDir目录中，创建一个名为myid的文件，并写入机器对应的数字值，比如我们是在zoo-1的机器上，就将该值设置为1，即集群中sever.1=zoo-1:2888:3888中server.后对应的数字。这是zookeeper用来识别是那一台集群机器的标识。
[root@localhost conf]# echo "1" > /usr/local/data/zookeeper/myid
此时我们集群中的一台服务器就配置好了
3、在其余两台机器上也安装zookeeper，可以通过scp命令直接拷贝文件即可。每个机器的都是用相同的配置信息。
[root@localhost conf]# scp -r /usr/local/soft/zookeeper/zookeeper-3.4.9/ root@192.168.100.102:/usr/local/soft/zookeeper root@192.168.100.102's password:
输入密码即可将对应的文件传输到要其他集群机器上。
注：此处唯一不同的地方是每个dataDir下的myid中的内容要按照zoo.cfg配置文件中的集群信息设置。比如：192.168.100.102对应集群中的server.2，所以在myid中写入2
到此为止，集群相关配置已经完毕了。下面就可以启动集群了
4、启动zookeeper集群
我的启动顺序是：zoo-1 -> zoo-2 --> zoo-3
[root@localhost zookeeper]# pwd /usr/local/soft/zookeeper [root@localhost zookeeper]# zookeeper-3.4.9/bin/zkServer.sh start ZooKeeper JMX enabled by default Using config: /usr/local/soft/zookeeper/zookeeper-3.4.9/bin/../conf/zoo.cfg Starting zookeeper ... STARTED
这样表明zoo-1的服务器已经启动，同时在我们当前操作路径下回生成一个zookeeper的日志文件，zookeeper.out
[root@localhost zookeeper]# pwd /usr/local/soft/zookeeper [root@localhost zookeeper]# ll 总用量 24 drwxr-xr-x. 10 1001 1001 4096 8月 23 2016 zookeeper-3.4.9 -rw-r--r--. 1 root root 19350 10月 27 23:54 zookeeper.out
文件中记录了集群的日志信息，当只启动zoo-1服务器的时候，日志中会出现异常，应为集群其他服务没启动，所以这个异常是没问题的。大概信息如下
[root@localhost zookeeper]# tailf zookeeper.out
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:381)
at org.apache.zookeeper.server.quorum.QuorumCnxManager.connectAll(QuorumCnxManager.java:426)
at org.apache.zookeeper.server.quorum.FastLeaderElection.lookForLeader(FastLeaderElection.java:843)
at org.apache.zookeeper.server.quorum.QuorumPeer.run(QuorumPeer.java:822)
2017-10-27 23:35:29,886 [myid:1] - INFO [QuorumPeer[myid=1]/0:0:0:0:0:0:0:0:2181:QuorumPeer$QuorumServer@149] - Resolved hostname: zoo-3 to address: zoo-3/192.168.100.103
2017-10-27 23:35:29,886 [myid:1] - INFO [QuorumPeer[myid=1]/0:0:0:0:0:0:0:0:2181:FastLeaderElection@852] - Notification time out: 3200
2017-10-27 23:35:33,088 [myid:1] - WARN [QuorumPeer[myid=1]/0:0:0:0:0:0:0:0:2181:QuorumCnxManager@400] - Cannot open channel to 2 at election address zoo-2/192.168.100.102:3888
java.net.ConnectException: 拒绝连接 (Connection refused)
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
at java.net.Socket.connect(Socket.java:589)
at org.apache.zookeeper.server.quorum.QuorumCnxManager.connectOne(QuorumCnxManager.java:381)
at org.apache.zookeeper.server.quorum.QuorumCnxManager.connectAll(QuorumCnxManager.java:426)
at org.apache.zookeeper.server.quorum.FastLeaderElection.lookForLeader(FastLeaderElection.java:843)
at org.apache.zookeeper.server.quorum.QuorumPeer.run(QuorumPeer.java:822)
2017-10-27 23:35:33,089 [myid:1] - INFO [QuorumPeer[myid=1]/0:0:0:0:0:0:0:0:2181:QuorumPeer$QuorumServer@149] - Resolved hostname: zoo-2 to address: zoo-2/192.168.100.102
2017-10-27 23:35:33,091 [myid:1] - WARN [QuorumPeer[myid=1]/0:0:0:0:0:0:0:0:2181:QuorumCnxManager@400] - Cannot open channel to 3 at election address zoo-3/192.168.100.103:3888
接着启动zoo-2和zoo-3,全部启动完毕后，集群会自动选举出一台服务器作为leader，其余服务器为follower。
可以在每台服务器上使用命令查看服务器是什么类型的:
[root@zoo-1 zookeeper]# zookeeper-3.4.9/bin/zkServer.sh status ZooKeeper JMX enabled by default Using config: /usr/local/soft/zookeeper/zookeeper-3.4.9/bin/../conf/zoo.cfg Mode: follower
[root@zoo-2 zookeeper]# zookeeper-3.4.9/bin/zkServer.sh status ZooKeeper JMX enabled by default Using config: /usr/local/soft/zookeeper/zookeeper-3.4.9/bin/../conf/zoo.cfg Mode: leader
[root@zoo-3 zookeeper]# zookeeper-3.4.9/bin/zkServer.sh status ZooKeeper JMX enabled by default Using config: /usr/local/soft/zookeeper/zookeeper-3.4.9/bin/../conf/zoo.cfg Mode: follower
通过上面状态查询结果可见，zoo-2是集群的Leader，其余的两个结点是Follower。可以通过客户端，连接到ZooKeeper集群上。对于客户端来说，ZooKeeper是一个整体（ensemble），你可以在任何一个结点上建立到服务集群的连接，例如：
[root@localhost zookeeper]# zookeeper-3.4.9/bin/zkCli.sh -server 192.168.100.101:2181 Connecting to 192.168.100.101:2181 2017-10-28 01:24:49,345 [myid:] - INFO [main:Environment@100] - Client environment:zookeeper.version=3.4.9-1757313, built on 08/23/2016 06:50 GMT 2017-10-28 01:24:49,350 [myid:] - INFO [main:Environment@100] - Client environment:host.name=localhost 2017-10-28 01:24:49,350 [myid:] - INFO [main:Environment@100] - Client environment:java.version=1.8.0_151 2017-10-28 01:24:49,358 [myid:] - INFO [main:Environment@100] - Client environment:java.vendor=Oracle Corporation 2017-10-28 01:24:49,358 [myid:] - INFO [main:Environment@100] - Client environment:java.home=/usr/local/soft/java/jdk1.8.0_151/jre 2017-10-28 01:24:49,359 [myid:] - INFO [main:Environment@100] - Client environment:java.class.path=/usr/local/soft/zookeeper/zookeeper-3.4.9/bin/../build/classes:/usr/local/soft/zookeeper/zookeeper-3.4.9/bin/../build/lib/*.jar:/usr/local/soft/zookeeper/zookeeper-3.4.9/bin/../lib/slf4j-log4j12-1.6.1.jar:/usr/local/soft/zookeeper/zookeeper-3.4.9/bin/../lib/slf4j-api-1.6.1.jar:/usr/local/soft/zookeeper/zookeeper-3.4.9/bin/../lib/netty-3.10.5.Final.jar:/usr/local/soft/zookeeper/zookeeper-3.4.9/bin/../lib/log4j-1.2.16.jar:/usr/local/soft/zookeeper/zookeeper-3.4.9/bin/../lib/jline-0.9.94.jar:/usr/local/soft/zookeeper/zookeeper-3.4.9/bin/../zookeeper-3.4.9.jar:/usr/local/soft/zookeeper/zookeeper-3.4.9/bin/../src/java/lib/*.jar:/usr/local/soft/zookeeper/zookeeper-3.4.9/bin/../conf: 2017-10-28 01:24:49,359 [myid:] - INFO [main:Environment@100] - Client environment:java.library.path=/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib 2017-10-28 01:24:49,359 [myid:] - INFO [main:Environment@100] - Client environment:java.io.tmpdir=/tmp 2017-10-28 01:24:49,359 [myid:] - INFO [main:Environment@100] - Client environment:java.compiler=<NA> 2017-10-28 01:24:49,359 [myid:] - INFO [main:Environment@100] - Client environment:os.name=Linux 2017-10-28 01:24:49,359 [myid:] - INFO [main:Environment@100] - Client environment:os.arch=amd64 2017-10-28 01:24:49,359 [myid:] - INFO [main:Environment@100] - Client environment:os.version=3.10.0-693.el7.x86_64 2017-10-28 01:24:49,359 [myid:] - INFO [main:Environment@100] - Client environment:user.name=root 2017-10-28 01:24:49,359 [myid:] - INFO [main:Environment@100] - Client environment:user.home=/root 2017-10-28 01:24:49,359 [myid:] - INFO [main:Environment@100] - Client environment:user.dir=/usr/local/soft/zookeeper 2017-10-28 01:24:49,360 [myid:] - INFO [main:ZooKeeper@438] - Initiating client connection, connectString=192.168.100.101:2181 sessionTimeout=30000 watcher=org.apache.zookeeper.ZooKeeperMain$MyWatcher@67424e82 2017-10-28 01:24:49,400 [myid:] - INFO [main-SendThread(192.168.100.101:2181):ClientCnxn$SendThread@1032] - Opening socket connection to server 192.168.100.101/192.168.100.101:2181. Will not attempt to authenticate using SASL (unknown error) Welcome to ZooKeeper! JLine support is enabled 2017-10-28 01:24:49,544 [myid:] - INFO [main-SendThread(192.168.100.101:2181):ClientCnxn$SendThread@876] - Socket connection established to 192.168.100.101/192.168.100.101:2181, initiating session 2017-10-28 01:24:49,560 [myid:] - INFO [main-SendThread(192.168.100.101:2181):ClientCnxn$SendThread@1299] - Session establishment complete on server 192.168.100.101/192.168.100.101:2181, sessionid = 0x15f5ed84b260001, negotiated timeout = 30000 WATCHER:: WatchedEvent state:SyncConnected type:None path:null [zk: 192.168.100.101:2181(CONNECTED) 0] ls / [zookeeper]
