本來這一節想寫Hadoop的分布式高可用環境的搭建，寫到一半，發現還是有必要先介紹一下ZooKeeper這個東西，
ZooKeeper理念介紹
ZooKeeper是為分布式應用來提供協同服務的，而且ZooKeeper本身也是分布式的，由分布在至少三臺機器上，這幾臺機器形成一個Quorum，就像一個劇團一樣，這個團里有個團長，就是leader的角色，其他的是follower，這個劇團里的每個人腦子里都記住同樣的東西（ZooKeeper是基于記憶體的），并且及時和leader保持同步，所有client可連接任何一個server即可，劇團里的每個人都有一個編號myid，如果劇團里的leader掛斷后，剩下的幾個要重新選舉出新的leader來確保服務正常運行，
1. ZooKeepe的安裝
ZooKeeper的安裝挺簡單，就是解壓，設定環境變數就可以了
[root@hadoop100 bin]# tar -zxvf /opt/software/zookeeper-3.4.10.tar.gz -C /opt/modules/
打開/ect/profile 編輯環境變數，加上下面的內容：
#JAVA_HOMEexport JAVA_HOME=/opt/modules/jdk1.8.0_121export PATH=$PATH:$JAVA_HOME/bin#HADOOP_HOMEexport HADOOP_HOME=/opt/modules/hadoop-2.7.3export PATH=$PATH:$HADOOP_HOME/bin:$HADOOP_HOME/sbin#ZOOKEEPERexport ZOOKEEPER_HOME=/opt/modules/zookeeper-3.4.10export PATH=$PATH:ZOOKEEPER_HOME/bin
然后 source /ect/profile 讓更改生效，記得用xsync 和xcall超級腳本，把更改同步到整個集群，
[root@hadoop100 bin]# xsync /etc/profile[root@hadoop100 bin]# xcall source /etc/profile2. ZooKeeper的配置
1. Zookeeper 需要一個data目錄，用于存盤zookeeper記憶體資料庫的鏡像和日志，然后更改zoo.cfg檔案，ZooKeeper解壓后提供了一個/opt/modules/zookeeper-3.4.10/conf/zoo_sample.cfg檔案，把這個復制一下或者改個名字叫zoo.cfg, 修改一下里面的dataDir的指向，
# The number of milliseconds of each ticktickTime=2000# The number of ticks that the initial# synchronization phase can takeinitLimit=10# The number of ticks that can pass between# sending a request and getting an acknowledgementsyncLimit=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 connectclientPort=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的機器環境，zookeeper服務器的數量應該是奇數臺，最少要3臺，
# 連接到leader 服務器的tick數，超過這個tick數 這臺服務器還沒有連接上leader，那這臺機器就被認為是死掉了initLimit = 5# 在和leader同步程序中所允許落后的最大tick數，如果超過這個，那就是掉隊了syncLimit = 2server.100=hadoop100:2888:3888server.101=hadoop101:2888:3888server.102=hadoop102:2888:3888server.103=hadoop103:2888:3888server.104=hadoop104:2888:3888
機器的引數配置的格式是這樣的：
Server.A=B:C:D，
A是一個數字，表示這個是第幾號服務器；
B是這個服務器的ip地址；
C是這個服務器與集群中的Leader服務器交換資訊的埠；
D是萬一集群中的Leader服務器掛了，需要一個埠來重新進行選舉，選出一個新的Leader，而這個埠就是用來執行選舉時服務器相互通信的埠，
注意更改完畢后別忘了分發到集群中，zookeeper本身是也分布式的，先把相關檔案分發到集群中的其他機器上，
[root@hadoop100 modules]# xsync zookeeper-3.4.10/
然后為每臺機器做上獨特的標記，在data目錄里創建myId檔案，內容就是上面組態檔中的數字
[root@hadoop100 zookeeper-3.4.10]# cd zkData/[root@hadoop100 zkData]# echo 100 > myid
在集群的其他幾臺機器上修改myid檔案的內容，讓myid的內容和組態檔中的編號一致，這時候只能麻煩點，依次登錄到每臺機器上創建 data目錄下的myid檔案了，
[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.
檢查一下確保沒問題
[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，準備啟動了，ZooKeeper集群都要啟動ZooKeeper服務，我用之前介紹過的超級腳本xcall. (后來發現用這種方式靠不住，說是啟動了，其實沒啟動 ;;;)
[root@hadoop100 zkData]# xcall /opt/modules/zookeeper-3.4.10/bin/zkServer.sh start---------running at localhost--------ZooKeeper JMX enabled by defaultUsing config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfgStarting zookeeper ... STARTED---------running at hadoop101-------ZooKeeper JMX enabled by defaultUsing config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfgStarting zookeeper ... STARTED---------running at hadoop102-------ZooKeeper JMX enabled by defaultUsing config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfgStarting zookeeper ... STARTED---------running at hadoop103-------ZooKeeper JMX enabled by defaultUsing config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfgStarting zookeeper ... STARTED---------running at hadoop104-------ZooKeeper JMX enabled by defaultUsing config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfgStarting zookeeper ... STARTED[root@hadoop100 zkData]#
錯誤排查：Error contacting service. It is probably not running.
查看一下運行狀態, 啊哦，怎么沒啟動呢？
[root@hadoop100 bin]# xcall /opt/modules/zookeeper-3.4.10/bin/zkServer.sh status---------running at localhost--------ZooKeeper JMX enabled by defaultUsing config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfgError contacting service. It is probably not running.---------running at hadoop101-------ZooKeeper JMX enabled by defaultUsing config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfgError contacting service. It is probably not running.---------running at hadoop102-------ZooKeeper JMX enabled by defaultUsing config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfgError contacting service. It is probably not running.---------running at hadoop103-------ZooKeeper JMX enabled by defaultUsing config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfgError contacting service. It is probably not running.---------running at hadoop104-------ZooKeeper JMX enabled by defaultUsing config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfgError contacting service. It is probably not running.[root@hadoop100 bin]#
后來發現需要單獨ssh到每臺機器上單獨啟動就可以了，可能是xcall神器有的時候不可靠，不過提示一點，zkServer.sh start-foreground 命令，可以在查看詳細啟動程序，方便排查錯誤，
[root@hadoop101 ~]# /opt/modules/zookeeper-3.4.10/bin/zkServer.sh start-foregroundZooKeeper JMX enabled by defaultUsing config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfg2019-09-19 14:52:29,093 [myid:] - INFO [main:QuorumPeerConfig@134] - Reading configuration from: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfg2019-09-19 14:52:29,122 [myid:] - INFO [main:QuorumPeer$QuorumServer@167] - Resolved hostname: hadoop104 to address: hadoop104/192.168.56.1042019-09-19 14:52:29,123 [myid:] - INFO [main:QuorumPeer$QuorumServer@167] - Resolved hostname: hadoop103 to address: hadoop103/192.168.56.1032019-09-19 14:52:29,123 [myid:] - INFO [main:QuorumPeer$QuorumServer@167] - Resolved hostname: hadoop102 to address: hadoop102/192.168.56.1022019-09-19 14:52:29,124 [myid:] - INFO [main:QuorumPeer$QuorumServer@167] - Resolved hostname: hadoop101 to address: hadoop101/192.168.56.1012019-09-19 14:52:29,124 [myid:] - INFO [main:QuorumPeer$QuorumServer@167] - Resolved hostname: hadoop100 to address: hadoop100/192.168.56.1002019-09-19 14:52:29,124 [myid:] - INFO [main:QuorumPeerConfig@396] - Defaulting to majority quorums2019-09-19 14:52:29,134 [myid:101] - INFO [main:DatadirCleanupManager@78] - autopurge.snapRetainCount set to 32019-09-19 14:52:29,135 [myid:101] - INFO [main:DatadirCleanupManager@79] - autopurge.purgeInterval set to 02019-09-19 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 peer2019-09-19 14:52:29,171 [myid:101] - INFO [main:NIOServerCnxnFactory@89] - binding to port 0.0.0.0/0.0.0.0:21812019-09-19 14:52:29,172 [myid:101] - ERROR [main:QuorumPeerMain@89] - Unexpected exception, exiting abnormallyjava.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就是已經啟動成功了，
[root@hadoop100 bin]# jps1885 QuorumPeerMain2029 Jps
SSH單獨登錄到各個服務器上依次啟動，并查看狀態，可以發現我現在的集群環境中hadoop102是leader，其他幾臺是follower：
[root@hadoop100 bin]# /opt/modules/zookeeper-3.4.10/bin/zkServer.sh statusZooKeeper JMX enabled by defaultUsing config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfgMode: follower[root@hadoop100 bin]# ssh hadoop101Last login: Thu Sep 19 15:04:12 2019 from hadoop100[root@hadoop101 ~]# /opt/modules/zookeeper-3.4.10/bin/zkServer.sh statusZooKeeper JMX enabled by defaultUsing config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfgMode: follower[root@hadoop101 ~]# exitlogoutConnection to hadoop101 closed.[root@hadoop100 bin]# ssh hadoop102Last login: Thu Sep 19 15:04:48 2019 from hadoop100[root@hadoop102 ~]# /opt/modules/zookeeper-3.4.10/bin/zkServer.sh statusZooKeeper JMX enabled by defaultUsing config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfgMode: leader[root@hadoop102 ~]# exitlogoutConnection to hadoop102 closed.[root@hadoop100 bin]# ssh hadoop103Last login: Thu Sep 19 15:05:07 2019 from hadoop100[root@hadoop103 ~]# /opt/modules/zookeeper-3.4.10/bin/zkServer.sh statusZooKeeper JMX enabled by defaultUsing config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfgMode: follower[root@hadoop103 ~]# exitlogoutConnection to hadoop103 closed.[root@hadoop100 bin]# ssh hadoop104Last login: Thu Sep 19 15:05:51 2019 from hadoop100[root@hadoop104 ~]# /opt/modules/zookeeper-3.4.10/bin/zkServer.sh statusZooKeeper JMX enabled by defaultUsing config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfgMode: follower[root@hadoop104 ~]# exitlogoutConnection to hadoop104 closed.[root@hadoop100 bin]#
好了，到現在為止，我的ZooKeeper集群環境已經搭建成功了，
題外話
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https://promotion.aliyun.com/ntms/yunparter/invite.html?userCode=vltv9frd
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