在CentOS 7 上安装Zookeeper集群

在CentOS 7 上安装Zookeeper集群

测试机上需要安装java软件
$ rpm -qa|grep java
$ sudo yum install -y java-1.8.0-openjdk.x86_64
$ java -version
openjdk version "1.8.0_65"
OpenJDK Runtime Environment (build 1.8.0_65-b17)
OpenJDK 64-Bit Server VM (build 25.65-b01, mixed mode)

1、创建用户：bjrenrui0001~0003
sudo groupadd zookeeper
sudo useradd -g zookeeper zookeeper
echo "zookeeper@1234"|sudo passwd zookeeper —stdin

2、创建工作目录
bjrenrui0001:
sudo mkdir /yanfa/mq
sudo ln -s /yanfa/mq /mq
sudo chown -R dreamjobs.dreamjobs /mq

bjrenrui0002~0003:
sudo mkdir mq
sudo chown dreamjobs.dreamjobs mq
sudo ln -s /home/backupfile/mq /mq
sudo chown dreamjobs.dreamjobs mq

1. 单机模式(Standalone mode)
下载，解压
cd /mq
wget http://mirror.bit.edu.cn/apache/zookeeper/zookeeper-3.4.7/zookeeper-3.4.7.tar.gz
tar zxvf zookeeper-3.4.7.tar.gz -C /mq
ln -s /mq/zookeeper-3.4.7 zookeeper

启动
默认就是单机模式
cd /mq/zookeeper/
cp ./conf/zoo_sample.cfg ./conf/zoo.cfg
sh ./bin/zkServer.sh start

防火墙开启2181端口

检查服务状态：
[dreamjobs@bjrenrui0001 bin]$ sh zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /mq/zookeeper/bin/../conf/zoo.cfg
Mode: standalone

使用java 客户端连接ZooKeeper
./bin/zkCli.sh -server 127.0.0.1:2181
然后就可以使用各种命令了，跟文件操作命令很类似，输入help可以看到所有命令。

关闭
sh bin/zkServer.sh stop

2 分布式模式(Replicated mode)
在生产环境中，要配置成分布式模式，才能发挥威力。
ZooKeeper集群一般被称为ZooKeeper ensemble(集成)，或者 quorum(法定人数).

准备3台机器

假设有三台机器，hostname和ip对应关系是：
192.168.100.200 bjrenrui0001
192.168.100.201 bjrenrui0002
192.168.100.202 bjrenrui0003

ZooKeeper不存在明显的master/slave关系，各个节点都是服务器，leader挂了，会立马从follower中选举一个出来作为leader.
由于没有主从关系，也不用配置SSH无密码登录了，各个zk服务器是自己启动的，互相之间通过TCP端口来交换数据。

创建日志和数据目录:
bjrenrui0001~0003
cd /mq/zookeeper
mkdir -p zookeeperdatadir/{logs,data}

修改bjrenrui0001的配置文件conf/zoo.cfg:
[dreamjobs@bjrenrui0001 conf]$ grep -vE '^($|#)' zoo.cfg
tickTime=2000
initLimit=10
syncLimit=5
dataDir=/mq/zookeeper/zookeeperdatadir/data
dataLogDir=/mq/zookeeper/zookeeperdatadir/logs
clientPort=2181
server.1=bjrenrui0001:2888:3888
server.2=bjrenrui0002:2888:3888
server.3=bjrenrui0003:2888:3888
修改完后拷贝到 bjrenrui0002,以及 bjrenrui0003上

myid文件:
要在每台机器的dataDir下，新建一个myid文件，里面存放一个数字，用来标识当前主机
bjrenrui0001: echo "1" >> /mq/zookeeper/zookeeperdatadir/data/myid
bjrenrui0002: echo "2" >> /mq/zookeeper/zookeeperdatadir/data/myid
bjrenrui0003: echo "3" >> /mq/zookeeper/zookeeperdatadir/data/myid

每台机器上启动zookeeper服务:
bjrenrui0001: sh /mq/zookeeper/bin/zkServer.sh start
bjrenrui0002: sh /mq/zookeeper/bin/zkServer.sh start
bjrenrui0003: sh /mq/zookeeper/bin/zkServer.sh start
每台机器上停止zookeeper服务:
bjrenrui0001: sh /mq/zookeeper/bin/zkServer.sh stop
bjrenrui0002: sh /mq/zookeeper/bin/zkServer.sh stop
bjrenrui0003: sh /mq/zookeeper/bin/zkServer.sh stop
因为3个节点的启动是有顺序的，所以在陆续启动三个节点的时候，前面先启动的节点连接未启动的节点的时候会报出一些错误,可以忽略。

防火墙开启2181端口：
sudo vi /etc/sysconfig/iptables
-A INPUT -p tcp -s 192.168.100.0/24 -j ACCEPT
sudo systemctl restart iptables.service

查看状态
[dreamjobs@bjrenrui0001 conf]$ gmbjyf.sh bjyfnbserver "cat /mq/zookeeper/zookeeperdatadir/data/myid"
bjrenrui0001
1
bjrenrui0002
2
bjrenrui0003
3
$ gmbjyf.sh bjyfnbserver "sh /mq/zookeeper/bin/zkServer.sh restart"
bjrenrui0001
ZooKeeper JMX enabled by default
Using config: /mq/zookeeper/bin/../conf/zoo.cfg
ZooKeeper JMX enabled by default
Using config: /mq/zookeeper/bin/../conf/zoo.cfg
Stopping zookeeper ... STOPPED
ZooKeeper JMX enabled by default
Using config: /mq/zookeeper/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED
bjrenrui0002
ZooKeeper JMX enabled by default
Using config: /mq/zookeeper/bin/../conf/zoo.cfg
ZooKeeper JMX enabled by default
Using config: /mq/zookeeper/bin/../conf/zoo.cfg
Stopping zookeeper ... STOPPED
ZooKeeper JMX enabled by default
Using config: /mq/zookeeper/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED
bjrenrui0003
ZooKeeper JMX enabled by default
Using config: /mq/zookeeper/bin/../conf/zoo.cfg
ZooKeeper JMX enabled by default
Using config: /mq/zookeeper/bin/../conf/zoo.cfg
Stopping zookeeper ... STOPPED
ZooKeeper JMX enabled by default
Using config: /mq/zookeeper/bin/../conf/zoo.cfg
Starting zookeeper … STARTED

$ gmbjyf.sh bjyfnbserver "sh /mq/zookeeper/bin/zkServer.sh status"
bjrenrui0001
ZooKeeper JMX enabled by default
Using config: /mq/zookeeper/bin/../conf/zoo.cfg
Mode: follower
bjrenrui0002
ZooKeeper JMX enabled by default
Using config: /mq/zookeeper/bin/../conf/zoo.cfg
Mode: leader
bjrenrui0003
ZooKeeper JMX enabled by default
Using config: /mq/zookeeper/bin/../conf/zoo.cfg
Mode: follower

使用java客户端连接ZooKeeper集群
找一台机器，解压zookeeper压缩包，不用配置，就可以使用java客户端连接ZooKeeper集群中的任意一台服务器了。
$ sh /mq/zookeeper/bin/zkCli.sh -server bjrenrui0001:2181
$ sh /mq/zookeeper/bin/zkCli.sh -server bjrenrui0002:2181
$ sh /mq/zookeeper/bin/zkCli.sh -server bjrenrui0003:2181