Zookeeper安装与使用-01Java环境安装搜索安装包安装jdk11查看当前版本配置环境变量编辑配置文件:vim/

Java环境安装

搜索安装包
```
yum -y list java-11*
```
安装jdk11
```
yum -y install java-11*
```
查看当前版本
```
java -version
```

配置环境变量

编辑配置文件: vim /etc/profile

export JAVA_HOME=/usr/lib/jvm/java-11-openjdk-11.0.10.0.9-0.el7_9.x86_64
export CLASSPATH=.:$JAVA_HOME/jre/lib/rt.jar:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
export PATH=$PATH:$JAVA_HOME/bin

刷新配置到内存,使其生效: source /etc/profile
测试是否生效: echo $JAVA_HOME

Zookeeper的安装

下载bin压缩包:

wget https://archive.apache.org/dist/zookeeper/zookeeper-3.5.6/apache-zookeeper-3.5.6-bin.tar.gz

解压:

tar  -zxvf apache-zookeeper-3.5.6-bin.tar.gz

移动到指定文件并重命名目录:

mv apache-zookeeper-3.5.6-bin/ /opt/zookeeper

配置环境变量:

编辑配置文件: vim /etc/profile

export JAVA_HOME=/usr/lib/jvm/java-11-openjdk-11.0.10.0.9-0.el7_9.x86_64
export CLASSPATH=.:$JAVA_HOME/jre/lib/rt.jar:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
export ZOOKEEPER_HOME=/opt/zookeeper
export PATH=$PATH:$JAVA_HOME/bin:$ZOOKEEPER_HOME/bin

刷新配置到内存,使其生效: source /etc/profile
测试是否生效: echo $ZOOKEEPER_HOME

单机模式

配置文件:
- 切换到指定目录: cd /opt/zookeeper/conf/
- 拷贝一份配置文件,一定得命名为zoo.cfg:
```
cp zoo_sample.cfg zoo.cfg
```
启动服务:
```
zkServer.sh start
```
验证服务:
- 使用telnet与stat两个命令验证服务是否正常
  - yum install telnet
```
telnet 127.0.0.1 2181
输入 stat
```
  - 解决白名单问题:
    - 打开vim /opt/zookeeper/bin/zkServer.sh并添加一行代码：
```
ZOOMAIN="-Dzookeeper.4lw.commands.whitelist=* ${ZOOMAIN}"
```
    - zkServer.sh restart重启服务:
    - 再次验证服务:

配置文件

# The number of milliseconds of each tick
# 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。
tickTime=2000
# The number of ticks that the initial 
# synchronization phase can take
# 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）
initLimit=10
# The number of ticks that can pass between 
# sending a request and getting an acknowledgement
# 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）
syncLimit=5
# the directory where the snapshot is stored.
# do not use /tmp for storage, /tmp here is just 
# example sakes.
# 配置持久化的文件目录
dataDir=/var/zookeeper
# 配置日志文件目录
dataLogDir=/opt/zookeeper/logs
# 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

集群模式

配置文件调整:

配置文件底部增加

# 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）
server.1=node01:2888:3888
server.2=node02:2888:3888
server.3=node03:2888:3888
server.4=node04:2888:3888

在/var/zookeeper目录下增加myid文件,内容如下:
```
1
```

前台阻塞启动服务:
```
 zkServer.sh start-foreground
```
- node01先启动,观察现象:报错，但是并未退出
- node02第二个启动,LOOKING状态
- node03第三个启动,leader产生,node01,node02也随之running起来了
- node03挂掉,node04选举出leader
- cZxid在每一个session连接的时候也算了一次