ZooKeeper集群

系统版本：CentOS Linux release 8.3.2011

JDK版本：1.8

Zookpeer版本：3.7.0

此次搭建的集群为伪集群，即在一台机器上开3个实例。

下载安装包

[root@i-h0xe1oiq tools]# wget https://dlcdn.apache.org/zookeeper/zookeeper-3.7.0/apache-zookeeper-3.7.0-bin.tar.gz

解压安装包

[root@i-h0xe1oiq tools]# tar xf apache-zookeeper-3.7.0-bin.tar.gz -C /application/

查看解压后的目录

[root@i-h0xe1oiq apache-zookeeper-3.7.0-bin]# tree -L 1
.
├── bin
├── conf
├── docs
├── lib
├── LICENSE.txt
├── NOTICE.txt
├── README.md
└── README_packaging.md

4 directories, 4 files

准备配置文件，进入conf目录，创建zoo.cfg文件，内容可复制conf/zoo_sample.cfg。
```
[root@i-h0xe1oiq conf]# cp zoo_sample.cfg zoo.cfg
```

配置文件说明

# The number of milliseconds of each tick
tickTime=2000
# CS通信心跳数，Zookeeper 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。tickTime以毫秒为单位。
# The number of ticks that the initial 
# synchronization phase can take
initLimit=10
# LF初始通信时限，集群中的follower服务器(F)与leader服务器(L)之间初始连接时能容忍的最多心跳数（tickTime的数量）。
# The number of ticks that can pass between 
# sending a request and getting an acknowledgement
syncLimit=5
# LF同步通信时限，集群中的follower服务器与leader服务器之间请求和应答之间能容忍的最多心跳数（tickTime的数量）。
# the directory where the snapshot is stored.
# do not use /tmp for storage, /tmp here is just 
# example sakes.
dataDir=/tmp/zookeeper
# 数据文件目录，Zookeeper保存数据的目录，默认情况下，Zookeeper将写数据的日志文件也保存在这个目录里。
# the port at which the clients will connect
clientPort=2181
# 客户端连接端口，客户端连接 Zookeeper 服务器的端口，Zookeeper 会监听这个端口，接受客户端的访问请求。
# 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

## Metrics Providers
#
# https://prometheus.io Metrics Exporter
#metricsProvider.className=org.apache.zookeeper.metrics.prometheus.PrometheusMetricsProvider
#metricsProvider.httpPort=7000
#metricsProvider.exportJvmInfo=true

# 服务器名称与地址：集群信息（服务器编号，服务器地址，LF通信端口，选举端口）
# 这个配置项的书写格式比较特殊，规则如下：

# server.N=YYY:A:B  

# 其中N表示服务器编号，YYY表示服务器的IP地址，A为LF通信端口，表示该服务器与集群中的leader交换的信息的端口。B为选举端口，表示选举新leader时服务器间相互通信的端口（当leader挂掉时，其余服务器会相互通信，选择出新的leader）。一般来说，集群中每个服务器的A端口都是一样，每个服务器的B端口也是一样。但是当所采用的为伪集群时，IP地址都一样，只能时A端口和B端口不一样。

伪集群准备三份zookeeper实例

[root@i-h0xe1oiq application]# ll -h
total 12K
drwxr-xr-x 17 cloud-user cloud-user 4.0K Mar 17  2021 apache-zookeeper-3.7.0-2181
drwxr-xr-x 17 root       root       4.0K Oct 25 14:54 apache-zookeeper-3.7.0-2182
drwxr-xr-x 17 root       root       4.0K Oct 25 14:54 apache-zookeeper-3.7.0-2183

各实例配置文件

# 实例1
tickTime=2000
initLimit=10
syncLimit=5
dataDir=/application/apache-zookeeper-3.7.0-2181/data
clientPort=2181
server.1=127.0.0.1:12888:13888
server.2=127.0.0.1:14888:15888
server.3=127.0.0.1:16888:17888

# 实例2
tickTime=2000
initLimit=10
syncLimit=5
dataDir=/application/apache-zookeeper-3.7.0-2182/data
clientPort=2182
server.1=127.0.0.1:12888:13888
server.2=127.0.0.1:14888:15888
server.3=127.0.0.1:16888:17888

# 实例3
tickTime=2000
initLimit=10
syncLimit=5
dataDir=/application/apache-zookeeper-3.7.0-2183/data
clientPort=2183
server.1=127.0.0.1:12888:13888
server.2=127.0.0.1:14888:15888
server.3=127.0.0.1:16888:17888

配置实例ID以区分

# 实例1
[root@i-h0xe1oiq application]# mkdir -p apache-zookeeper-3.7.0-2181/data/ && echo 1 > apache-zookeeper-3.7.0-2181/data/myid

# 实例2
[root@i-h0xe1oiq application]# mkdir -p apache-zookeeper-3.7.0-2182/data/ && echo 2 > apache-zookeeper-3.7.0-2182/data/myid

# 实例3
[root@i-h0xe1oiq application]# mkdir -p apache-zookeeper-3.7.0-2183/data/ && echo 3 > apache-zookeeper-3.7.0-2183/data/myid

启动节点

[root@i-h0xe1oiq application]# ./apache-zookeeper-3.7.0-2181/bin/zkServer.sh start
ZooKeeper JMX enabled by default
Using config: /application/apache-zookeeper-3.7.0-2181/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED
[root@i-h0xe1oiq application]# ./apache-zookeeper-3.7.0-2182/bin/zkServer.sh start
ZooKeeper JMX enabled by default
Using config: /application/apache-zookeeper-3.7.0-2182/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED
[root@i-h0xe1oiq application]# ./apache-zookeeper-3.7.0-2183/bin/zkServer.sh start
ZooKeeper JMX enabled by default
Using config: /application/apache-zookeeper-3.7.0-2183/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED

查看节点状态

[root@i-h0xe1oiq application]# ./apache-zookeeper-3.7.0-2181/bin/zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /application/apache-zookeeper-3.7.0-2181/bin/../conf/zoo.cfg
Client port found: 2181. Client address: localhost. Client SSL: false.
Mode: follower
[root@i-h0xe1oiq application]# ./apache-zookeeper-3.7.0-2182/bin/zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /application/apache-zookeeper-3.7.0-2182/bin/../conf/zoo.cfg
Client port found: 2182. Client address: localhost. Client SSL: false.
Mode: leader
[root@i-h0xe1oiq application]# ./apache-zookeeper-3.7.0-2183/bin/zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /application/apache-zookeeper-3.7.0-2183/bin/../conf/zoo.cfg
Client port found: 2183. Client address: localhost. Client SSL: false.
Mode: follower