[大数据学习研究] 4. Zookeeper-分布式服务的协同管理神器
本来这一节想写Hadoop的分布式高可用环境的搭建，写到一半，发现还是有必要先介绍一下ZooKeeper这个东西。
ZooKeeper理念介绍
ZooKeeper是为分布式应用来提供协同服务的，而且ZooKeeper本身也是分布式的，由分布在至少三台机器上，这几台机器形成一个Quorum，就像一个剧团一样。这个团里有个团长，就是leader的角色，其他的是follower。这个剧团里的每个人脑子里都记住同样的东西（ZooKeeper是基于内存的），并且及时和leader保持同步，所有client可连接任何一个server即可。剧团里的每个人都有一个编号myid。如果剧团里的leader挂断后，剩下的几个要重新选举出新的leader来确保服务正常运行。
![[大数据学习研究] 4. Zookeeper-分布式服务的协同管理神器_第1张图片](http://img.e-com-net.com/image/info8/3953cc5d779a463a96fabc4e69e04c5c.jpg)
1. ZooKeepe的安装
ZooKeeper的安装挺简单，就是解压，设置环境变量就可以了
[root@hadoop100 bin]# tar -zxvf /opt/software/zookeeper-3.4.10.tar.gz -C /opt/modules/
打开/ect/profile 编辑环境变量，加上下面的内容：
#JAVA_HOME export JAVA_HOME=/opt/modules/jdk1.8.0_121 export PATH=$PATH:$JAVA_HOME/bin #HADOOP_HOME export HADOOP_HOME=/opt/modules/hadoop-2.7.3 export PATH=$PATH:$HADOOP_HOME/bin:$HADOOP_HOME/sbin #ZOOKEEPER export ZOOKEEPER_HOME=/opt/modules/zookeeper-3.4.10 export PATH=$PATH:ZOOKEEPER_HOME/bin
然后 source /ect/profile 让更改生效。记得用xsync 和xcall超级脚本，把更改同步到整个集群。
[root@hadoop100 bin]# xsync /etc/profile
[root@hadoop100 bin]# xcall source /etc/profile
2. ZooKeeper的配置
1. Zookeeper 需要一个data目录，用于存储zookeeper内存数据库的镜像和日志。然后更改zoo.cfg文件。ZooKeeper解压后提供了一个/opt/modules/zookeeper-3.4.10/conf/zoo_sample.cfg文件，把这个复制一下或者改个名字叫zoo.cfg, 修改一下里面的dataDir的指向。
# 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=/opt/modules/zookeeper-3.4.10/zkData # 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 # # Be sure to read the maintenance section of the # administrator guide before turning on autopurge. # # http://zookeeper.apache.org/doc/current/zookeeperAdmin.html#sc_maintenance # # The number of snapshots to retain in dataDir #autopurge.snapRetainCount=3 # Purge task interval in hours # Set to "0" to disable auto purge feature #autopurge.purgeInterval=1 ~
要搭建ZooKeeper的机器环境，zookeeper服务器的数量应该是奇数台。最少要3台。
# 连接到leader 服务器的tick数，超过这个tick数 这台服务器还没有连接上leader，那这台机 器就被认为是死掉了 initLimit = 5 # 在和leader同步过程中所允许落后的最大tick数，如果超过这个，那就是掉队了 syncLimit = 2 server.100=hadoop100:2888:3888 server.101=hadoop101:2888:3888 server.102=hadoop102:2888:3888 server.103=hadoop103:2888:3888 server.104=hadoop104:2888:3888
机器的参数配置的格式是这样的：
Server.A=B:C:D。
A是一个数字，表示这个是第几号服务器；
B是这个服务器的ip地址；
C是这个服务器与集群中的Leader服务器交换信息的端口；
D是万一集群中的Leader服务器挂了，需要一个端口来重新进行选举，选出一个新的Leader，而这个端口就是用来执行选举时服务器相互通信的端口。
注意更改完毕后别忘了分发到集群中。zookeeper本身是也分布式的。先把相关文件分发到集群中的其他机器上。
[root@hadoop100 modules]# xsync zookeeper-3.4.10/
然后为每台机器做上独特的标记，在data目录里创建myId文件，内容就是上面配置文件中的数字
[root@hadoop100 zookeeper-3.4.10]# cd zkData/ [root@hadoop100 zkData]# echo 100 > myid
在集群的其他几台机器上修改myid文件的内容，让myid的内容和配置文件中的编号一致。这时候只能麻烦点，依次登录到每台机器上创建 data目录下的myid文件了。
[root@hadoop100 zkData]# ssh hadoop101
Last login: Thu Sep 19 14:10:35 2019 from gateway [root@hadoop101 ~]# echo 101 > /opt/modules/zookeeper-3.4.10/zkData/myid
[root@hadoop101 ~]#exit
[root@hadoop100 zkData]# ssh hadoop101
Last login: Thu Sep 19 14:10:35 2019 from gateway
[root@hadoop101 ~]# echo 101 > /opt/modules/zookeeper-3.4.10/zkData/myid
[root@hadoop101 ~]# exit
logout
Connection to hadoop101 closed.
[root@hadoop100 zkData]# ssh hadoop102
Last login: Tue Sep 17 13:26:48 2019 from hadoop100
[root@hadoop102 ~]# echo 102 > /opt/modules/zookeeper-3.4.10/zkData/myid
[root@hadoop102 ~]# exit
logout
Connection to hadoop102 closed.
[root@hadoop100 zkData]# ssh hadoop103
Last login: Tue Sep 17 13:17:00 2019 from hadoop100
[root@hadoop103 ~]# echo 103 > /opt/modules/zookeeper-3.4.10/zkData/myid
[root@hadoop103 ~]# exit
logout
Connection to hadoop103 closed.
[root@hadoop100 zkData]# ssh hadoop104
Last login: Tue Sep 17 11:04:38 2019 from hadoop100
[root@hadoop104 ~]# echo 104 > /opt/modules/zookeeper-3.4.10/zkData/myid
[root@hadoop104 ~]# exit
logout
Connection to hadoop104 closed.
检查一下确保没问题
[root@hadoop100 bin]# xcall cat /opt/modules/zookeeper-3.4.10/zkData/myid ---------running at localhost-------- 100 ---------running at hadoop101------- 101 ---------running at hadoop102------- 102 ---------running at hadoop103------- 103 ---------running at hadoop104------- 104 [root@hadoop100 bin]#
好了，基本配置好了，准备启动了，ZooKeeper集群都要启动ZooKeeper服务。我用之前介绍过的超级脚本xcall. (后来发现用这种方式靠不住，说是启动了，其实没启动 ;;;)
[root@hadoop100 zkData]# xcall /opt/modules/zookeeper-3.4.10/bin/zkServer.sh start ---------running at localhost-------- ZooKeeper JMX enabled by default Using config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfg Starting zookeeper ... STARTED ---------running at hadoop101------- ZooKeeper JMX enabled by default Using config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfg Starting zookeeper ... STARTED ---------running at hadoop102------- ZooKeeper JMX enabled by default Using config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfg Starting zookeeper ... STARTED ---------running at hadoop103------- ZooKeeper JMX enabled by default Using config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfg Starting zookeeper ... STARTED ---------running at hadoop104------- ZooKeeper JMX enabled by default Using config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfg Starting zookeeper ... STARTED [root@hadoop100 zkData]#
错误排查：Error contacting service. It is probably not running.
查看一下运行状态, 啊哦，怎么没启动呢？
[root@hadoop100 bin]# xcall /opt/modules/zookeeper-3.4.10/bin/zkServer.sh status ---------running at localhost-------- ZooKeeper JMX enabled by default Using config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfg Error contacting service. It is probably not running. ---------running at hadoop101------- ZooKeeper JMX enabled by default Using config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfg Error contacting service. It is probably not running. ---------running at hadoop102------- ZooKeeper JMX enabled by default Using config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfg Error contacting service. It is probably not running. ---------running at hadoop103------- ZooKeeper JMX enabled by default Using config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfg Error contacting service. It is probably not running. ---------running at hadoop104------- ZooKeeper JMX enabled by default Using config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfg Error contacting service. It is probably not running. [root@hadoop100 bin]#
后来发现需要单独ssh到每台机器上单独启动就可以了，可能是xcall神器有的时候不可靠。不过提示一点，zkServer.sh start-foreground 命令，可以在查看详细启动过程，方便排查错误。
[root@hadoop101 ~]# /opt/modules/zookeeper-3.4.10/bin/zkServer.sh start-foreground ZooKeeper JMX enabled by default Using config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfg 2019-09-19 14:52:29,093 [myid:] - INFO [main:QuorumPeerConfig@134] - Reading configuration from: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfg 2019-09-19 14:52:29,122 [myid:] - INFO [main:QuorumPeer$QuorumServer@167] - Resolved hostname: hadoop104 to address: hadoop104/192.168.56.104 2019-09-19 14:52:29,123 [myid:] - INFO [main:QuorumPeer$QuorumServer@167] - Resolved hostname: hadoop103 to address: hadoop103/192.168.56.103 2019-09-19 14:52:29,123 [myid:] - INFO [main:QuorumPeer$QuorumServer@167] - Resolved hostname: hadoop102 to address: hadoop102/192.168.56.102 2019-09-19 14:52:29,124 [myid:] - INFO [main:QuorumPeer$QuorumServer@167] - Resolved hostname: hadoop101 to address: hadoop101/192.168.56.101 2019-09-19 14:52:29,124 [myid:] - INFO [main:QuorumPeer$QuorumServer@167] - Resolved hostname: hadoop100 to address: hadoop100/192.168.56.100 2019-09-19 14:52:29,124 [myid:] - INFO [main:QuorumPeerConfig@396] - Defaulting to majority quorums 2019-09-19 14:52:29,134 [myid:101] - INFO [main:DatadirCleanupManager@78] - autopurge.snapRetainCount set to 3 2019-09-19 14:52:29,135 [myid:101] - INFO [main:DatadirCleanupManager@79] - autopurge.purgeInterval set to 0 2019-09-19 14:52:29,135 [myid:101] - INFO [main:DatadirCleanupManager@101] - Purge task is not scheduled. 2019-09-19 14:52:29,150 [myid:101] - INFO [main:QuorumPeerMain@127] - Starting quorum peer 2019-09-19 14:52:29,171 [myid:101] - INFO [main:NIOServerCnxnFactory@89] - binding to port 0.0.0.0/0.0.0.0:2181 2019-09-19 14:52:29,172 [myid:101] - ERROR [main:QuorumPeerMain@89] - Unexpected exception, exiting abnormally java.net.BindException: Address already in use 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 sun.nio.ch.ServerSocketAdaptor.bind(ServerSocketAdaptor.java:67) at org.apache.zookeeper.server.NIOServerCnxnFactory.configure(NIOServerCnxnFactory.java:90) at org.apache.zookeeper.server.quorum.QuorumPeerMain.runFromConfig(QuorumPeerMain.java:130) at org.apache.zookeeper.server.quorum.QuorumPeerMain.initializeAndRun(QuorumPeerMain.java:111) at org.apache.zookeeper.server.quorum.QuorumPeerMain.main(QuorumPeerMain.java:78) [root@hadoop101 ~]#
如果jps命令能看到QuorumPeerMain就是已经启动成功了。
[root@hadoop100 bin]# jps 1885 QuorumPeerMain 2029 Jps
SSH单独登录到各个服务器上依次启动，并查看状态，可以发现我现在的集群环境中hadoop102是leader，其他几台是follower：
[root@hadoop100 bin]# /opt/modules/zookeeper-3.4.10/bin/zkServer.sh status ZooKeeper JMX enabled by default Using config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfg Mode: follower [root@hadoop100 bin]# ssh hadoop101 Last login: Thu Sep 19 15:04:12 2019 from hadoop100 [root@hadoop101 ~]# /opt/modules/zookeeper-3.4.10/bin/zkServer.sh status ZooKeeper JMX enabled by default Using config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfg Mode: follower [root@hadoop101 ~]# exit logout Connection to hadoop101 closed. [root@hadoop100 bin]# ssh hadoop102 Last login: Thu Sep 19 15:04:48 2019 from hadoop100 [root@hadoop102 ~]# /opt/modules/zookeeper-3.4.10/bin/zkServer.sh status ZooKeeper JMX enabled by default Using config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfg Mode: leader [root@hadoop102 ~]# exit logout Connection to hadoop102 closed. [root@hadoop100 bin]# ssh hadoop103 Last login: Thu Sep 19 15:05:07 2019 from hadoop100 [root@hadoop103 ~]# /opt/modules/zookeeper-3.4.10/bin/zkServer.sh status ZooKeeper JMX enabled by default Using config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfg Mode: follower [root@hadoop103 ~]# exit logout Connection to hadoop103 closed. [root@hadoop100 bin]# ssh hadoop104 Last login: Thu Sep 19 15:05:51 2019 from hadoop100 [root@hadoop104 ~]# /opt/modules/zookeeper-3.4.10/bin/zkServer.sh status ZooKeeper JMX enabled by default Using config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfg Mode: follower [root@hadoop104 ~]# exit logout Connection to hadoop104 closed. [root@hadoop100 bin]#
好了，到现在为止，我的ZooKeeper集群环境已经搭建成功了。
题外话
学习研究的话可以用虚拟机，真要认真做点事还是要上云，比如阿里云。如果你需要，可以用我的下面这个链接，有折扣返现。
https://promotion.aliyun.com/ntms/yunparter/invite.html?userCode=vltv9frd