Zookeeper（二、分布式集群安装与命令行操作）

原文链接： Zookeeper（二、分布式集群安装与命令行操作）.

1. 前置条件

安装Hadoop集群
链接： Hadoop（二、安装Hadoop-3.2.1集群）.
在hadoop100、hadoop101和hadoop102三个节点上部署Zookeeper。

使用的是Zookeeper-3.6.1版本
链接：https://pan.baidu.com/s/1PKpjntrFyT-yiF20EdlL_Q
提取码：c0ol

2．解压安装

1. 上传压缩包到centos7 ，hadoop100机器上

# 使用rz命令上传压缩包
[root@hadoop100 ~]# cd /opt/tar.gz/
[root@hadoop100 tar.gz]# rz 

2. 解压Zookeeper安装包到/opt/module/目录下

[root@hadoop100 tar.gz]# ls
apache-zookeeper-3.6.1-bin.tar.gz  hadoop-3.2.1.tar.gz  jdk-8u251-linux-x64.tar.gz
[root@hadoop100 tar.gz]# tar -zxvf apache-zookeeper-3.6.1-bin.tar.gz -C /opt/software/
[root@hadoop100 tar.gz]# cd /opt/software/
[root@hadoop100 software]# ls
apache-zookeeper-3.6.1-bin  hadoop-3.2.1  jdk1.8.0_251

3. 同步**/opt/software/apache-zookeeper-3.6.1-bin**目录内容到hadoop101、hadoop102

[root@hadoop100 software]# xsync apache-zookeeper-3.6.1-bin/
[root@hadoop100 software]# ssh hadoop101
Last login: Fri Jun 19 00:29:21 2020 from hadoop100
[root@hadoop101 ~]# cd /opt/software/
[root@hadoop101 software]# ls
apache-zookeeper-3.6.1-bin  hadoop-3.2.1  jdk1.8.0_251
[root@hadoop101 software]# ssh hadoop102
Last login: Fri Jun 19 00:29:30 2020 from hadoop101
[root@hadoop102 ~]# cd /opt/software/
[root@hadoop102 software]# ls
apache-zookeeper-3.6.1-bin  hadoop-3.2.1  jdk1.8.0_251
[root@hadoop102 software]# 

3. 配置服务器编号

1. 在**/opt/software/apache-zookeeper-3.6.1-bin这个目录下创建zkData**，在目录下下创建一个myid的文件

[root@hadoop102 software]# ssh hadoop100
[root@hadoop100 ~]# cd /opt/software/apache-zookeeper-3.6.1-bin/
[root@hadoop100 apache-zookeeper-3.6.1-bin]# mkdir zkData
[root@hadoop100 apache-zookeeper-3.6.1-bin]# ls
bin  conf  docs  lib  LICENSE.txt  NOTICE.txt  README.md  README_packaging.md  zkData
[root@hadoop100 apache-zookeeper-3.6.1-bin]# cd zkData/
[root@hadoop100 zkData]# touch myid
[root@hadoop100 zkData]# ls
myid

2. 编辑myid文件，在文件中添加与server对应的编号。

[root@hadoop100 zkData]# cd ..
[root@hadoop100 apache-zookeeper-3.6.1-bin]# xsync zkData/ # 分发文件到hadoop101,hadoop102
[root@hadoop100 apache-zookeeper-3.6.1-bin]# cd zkData/
[root@hadoop100 zkData]# vi myid 
100

:wq
[root@hadoop100 zkData]# ssh hadoop101
Last login: Tue Jun 23 23:15:35 2020 from hadoop100
[root@hadoop101 ~]# cd /opt/software/apache-zookeeper-3.6.1-bin/zkData/
[root@hadoop101 zkData]# vi myid 
101

:wq
[root@hadoop101 zkData]# ssh hadoop102
Last login: Tue Jun 23 23:15:55 2020 from hadoop101
[root@hadoop102 ~]# cd /opt/software/apache-zookeeper-3.6.1-bin/zkData/
[root@hadoop102 zkData]# vi myid 
102

:wq

4. 配置

4.1 配置参数解读

Zookeeper中的配置文件zoo.cfg中参数含义解读如下：

1. tickTime =2000：通信心跳数，Zookeeper服务器与客户端心跳时间，单位毫秒
   Zookeeper使用的基本时间，服务器之间或客户端与服务器之间维持心跳的时间间隔，也就是每个tickTime时间就会发送一个心跳，时间单位为毫秒。
   它用于心跳机制，并且设置最小的session超时时间为两倍心跳时间。(session的最小超时时间是2*tickTime)
2. initLimit =10：LF初始通信时限
   集群中的Follower跟随者服务器与Leader领导者服务器之间初始连接时能容忍的最多心跳数（tickTime的数量），用它来限定集群中的Zookeeper服务器连接到Leader的时限。
3. syncLimit =5：LF同步通信时限
   集群中Leader与Follower之间的最大响应时间单位，假如响应超过syncLimit * tickTime，Leader认为Follwer死掉，从服务器列表中删除Follwer。
4. dataDir：数据文件目录+数据持久化路径
   主要用于保存Zookeeper中的数据。
5. clientPort =2181：客户端连接端口
   监听客户端连接的端口。
6. server.A=B:C:D：
   A是一个数字，表示这个是第几号服务器；
   集群模式下配置一个文件myid，这个文件在dataDir目录下，这个文件里面有一个数据就是A的值，Zookeeper启动时读取此文件，拿到里面的数据与zoo.cfg里面的配置信息比较从而判断到底是哪个server。
   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。

4.2 配置zoo.cfg文件

1. 重命名**/opt/software/apache-zookeeper-3.6.1-bin/conf目录下的zoo_sample.cfg为zoo.cfg**

[root@hadoop100 ~]# cd /opt/software/apache-zookeeper-3.6.1-bin/conf/
[root@hadoop100 conf]# ls
configuration.xsl  log4j.properties  zoo_sample.cfg
[root@hadoop100 conf]# mv zoo_sample.cfg zoo.cfg
[root@hadoop100 conf]# ls
configuration.xsl  log4j.properties  zoo.cfg

2. 打开zoo.cfg文件，修改数据存储路径配置

vi zoo.cfg

增加如下配置

3. 同步zoo.cfg

[root@hadoop100 conf]# xsync zoo.cfg 

5. 集群操作

1. 分别启动Zookeeper

[root@hadoop100 apache-zookeeper-3.6.1-bin]# bin/zkServer.sh start
[root@hadoop101 apache-zookeeper-3.6.1-bin]# bin/zkServer.sh start
[root@hadoop102 apache-zookeeper-3.6.1-bin]# bin/zkServer.sh start

2. 查看状态

[root@hadoop100 bin]# ./zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /opt/software/apache-zookeeper-3.6.1-bin/bin/../conf/zoo.cfg
Client port found: 2181. Client address: localhost.
Mode: follower
[root@hadoop101 bin]# ./zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /opt/software/apache-zookeeper-3.6.1-bin/bin/../conf/zoo.cfg
Client port found: 2181. Client address: localhost.
Mode: leader
[root@hadoop102 apache-zookeeper-3.6.1-bin]# bin/zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /opt/software/apache-zookeeper-3.6.1-bin/bin/../conf/zoo.cfg
Client port found: 2181. Client address: localhost.
Mode: follower

看到当前hadoop100，hadoop102是follower；hadoop101是leader说明Zookeeper选举机制正常运行
有关Zookeeper的基础和原理可以看我上一篇文章：
链接：Zookeeper（一、大数据之ZooKeeper基础与原理）.

6. 客户端命令行操作

6.1 启动客户端

[root@hadoop100 apache-zookeeper-3.6.1-bin]# bin/zkCli.sh

6.2 显示所有操作命令

6.3 查看当前znode中所包含的内容

zk: localhost:2181(CONNECTED) 2] ls /
[zookeeper]

6.4 查看当前节点详细数据

[zk: localhost:2181(CONNECTED) 4] ls -s /
[zookeeper]
cZxid = 0x0
ctime = Thu Jan 01 08:00:00 CST 1970
mZxid = 0x0
mtime = Thu Jan 01 08:00:00 CST 1970
pZxid = 0x0
cversion = -1
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 0
numChildren = 1

6.5. 创建2个普通节点（默认创建持久节点）

[zk: localhost:2181(CONNECTED) 1] create /sanguo "jinlian"
Created /sanguo
[zk: localhost:2181(CONNECTED) 2] create /sanguo/shuguo "liubei"
Created /sanguo/shuguo
[zk: localhost:2181(CONNECTED) 3] ls /
[sanguo, zookeeper]
[zk: localhost:2181(CONNECTED) 4] ls /sanguo
[shuguo]

6.6 获得节点的值

[zk: localhost:2181(CONNECTED) 5] get /sanguo
jinlian
[zk: localhost:2181(CONNECTED) 6] get /sanguo/shuguo
liubei
[zk: localhost:2181(CONNECTED) 7] get -s /sanguo
jinlian
cZxid = 0x100000004
ctime = Wed Jun 24 00:04:51 CST 2020
mZxid = 0x100000004
mtime = Wed Jun 24 00:04:51 CST 2020
pZxid = 0x100000005
cversion = 1
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 7
numChildren = 1
[zk: localhost:2181(CONNECTED) 8] get -s /sanguo/shuguo
liubei
cZxid = 0x100000005
ctime = Wed Jun 24 00:05:10 CST 2020
mZxid = 0x100000005
mtime = Wed Jun 24 00:05:10 CST 2020
pZxid = 0x100000005
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 6
numChildren = 0

6.7 创建短暂节点

[zk: localhost:2181(CONNECTED) 9] create -e /sanguo/wuguo
Created /shuguo
[zk: localhost:2181(CONNECTED) 10] ls /sanguo
[shuguo, wuguo]
[zk: localhost:2181(CONNECTED) 10] quit
[root@hadoop100 apache-zookeeper-3.6.1-bin]# bin/zkCli.sh
[zk: localhost:2181(CONNECTED) 1] ls /sanguo
[shuguo]

发现客户端退出之后，刚刚创建的节点 /shuguo 就被删除了

6.8 创建带序号的节点

A. 先创建一个普通的根节点/sanguo/weiguo

[zk: localhost:2181(CONNECTED) 0] create /sanguo/weiguo
Created /sanguo/weiguo
[zk: localhost:2181(CONNECTED) 1] ls /sanguo
[shuguo, weiguo]

B. 创建带序号的节点

[zk: localhost:2181(CONNECTED) 2] create -s /sanguo/weiguo "caocao"
Created /sanguo/weiguo0000000003
[zk: localhost:2181(CONNECTED) 3] create -s /sanguo/weiguo "caocao"
Created /sanguo/weiguo0000000004
[zk: localhost:2181(CONNECTED) 4] create -s /sanguo/weiguo "caocao"
Created /sanguo/weiguo0000000005

如果原来没有序号节点，序号从0开始依次递增。如果原节点下已有2个节点，则再排序时从2开始，以此类推。

6.9 修改节点数据值

[zk: localhost:2181(CONNECTED) 8] set /sanguo/shuguo "diaocan"
[zk: localhost:2181(CONNECTED) 9] get -s /sanguo/shuguo
diaocan
cZxid = 0x100000005
ctime = Wed Jun 24 00:05:10 CST 2020
mZxid = 0x100000011
mtime = Wed Jun 24 00:22:34 CST 2020
pZxid = 0x100000005
cversion = 0
dataVersion = 1
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 7
numChildren = 0
[zk: localhost:2181(CONNECTED) 10] set /sanguo/shuguo "lvbu"
[zk: localhost:2181(CONNECTED) 11] get -s /sanguo/shuguo
lvbu
cZxid = 0x100000005
ctime = Wed Jun 24 00:05:10 CST 2020
mZxid = 0x100000012
mtime = Wed Jun 24 00:23:26 CST 2020
pZxid = 0x100000005
cversion = 0
dataVersion = 2
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 4
numChildren = 0

6.10 节点的值变化监听

在 hadoop102 上注册监听 /sanguo 节点数据变化

[zk: localhost:2181(CONNECTED) 3] get -s -w /sanguo 
jinlian
cZxid = 0x100000004
ctime = Wed Jun 24 00:04:51 CST 2020
mZxid = 0x100000004
mtime = Wed Jun 24 00:04:51 CST 2020
pZxid = 0x10000000f
cversion = 7
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 7
numChildren = 5

发现在这时候的值还是刚开始创建的值**“jinlian”**

在hadoop100上修改**/sanguo**节点的数据

[zk: localhost:2181(CONNECTED) 13] set /sanguo "guanyu"

回到hadoop102上发现提示有数据，但是此时为一次性监听，之后再次修改不会提示。（之后在Zookeeper工程中可以根据逻辑进行永久监听）！

6.11 删除节点

[zk: localhost:2181(CONNECTED) 18] ls /sanguo
[shuguo, weiguo, weiguo0000000003, weiguo0000000004, weiguo0000000005]
[zk: localhost:2181(CONNECTED) 19] delete /sanguo/weiguo0000000003
[zk: localhost:2181(CONNECTED) 20] ls /sanguo
[shuguo, weiguo, weiguo0000000004, weiguo0000000005]
[zk: localhost:2181(CONNECTED) 21] deleteall /sanguo
[zk: localhost:2181(CONNECTED) 22] ls /
[zookeeper]

6.12 查看节点状态

[zk: localhost:2181(CONNECTED) 25] stat /zookeeper
cZxid = 0x0
ctime = Thu Jan 01 08:00:00 CST 1970
mZxid = 0x0
mtime = Thu Jan 01 08:00:00 CST 1970
pZxid = 0x0
cversion = -2
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 0
numChildren = 2

参考资料：
链接：尚硅谷Zookeeper教程(zookeeper框架精讲).