Docker环境搭建ZooKeeper集群

序

本文将介绍如何在docker中部署zookeeper集群。

部署环境

CentOS 7 host A 192.168.199.200

CentOS 7 host B 192.168.199.201

CentOS 7 host C 192.168.199.202

部署

host A 部署zookeeper

docker run -d \
 --name=zookeeper \
 --net=host \
 -e SERVER_ID=1 \
 -e ADDITIONAL_ZOOKEEPER_1=server.1=192.168.199.200:2888:3888 \
 -e ADDITIONAL_ZOOKEEPER_2=server.2=192.168.199.201:2888:3888 \
 -e ADDITIONAL_ZOOKEEPER_3=server.3=192.168.199.202:2888:3888 \
 -e ADDITIONAL_ZOOKEEPER_4=clientPort=2181 \
 garland/zookeeper

host B 部署zookeeper

docker run -d \
 --name=zookeeper \
 --net=host \
 -e SERVER_ID=2 \
 -e ADDITIONAL_ZOOKEEPER_1=server.1=192.168.199.200:2888:3888 \
 -e ADDITIONAL_ZOOKEEPER_2=server.2=192.168.199.201:2888:3888 \
 -e ADDITIONAL_ZOOKEEPER_3=server.3=192.168.199.202:2888:3888 \
 -e ADDITIONAL_ZOOKEEPER_4=clientPort=2181 \
 garland/zookeeper

host C 部署zookeeper

docker run -d \
 --name=zookeeper \
 --net=host \
 -e SERVER_ID=3 \
 -e ADDITIONAL_ZOOKEEPER_1=server.1=192.168.199.200:2888:3888 \
 -e ADDITIONAL_ZOOKEEPER_2=server.2=192.168.199.201:2888:3888 \
 -e ADDITIONAL_ZOOKEEPER_3=server.3=192.168.199.202:2888:3888 \
 -e ADDITIONAL_ZOOKEEPER_4=clientPort=2181 \
 garland/zookeeper

查看部署结果

host A follower

[root@localhost zookeeper]# echo stat | nc 127.0.0.1 2181
Zookeeper version: 3.4.6-1569965, built on 02/20/2014 09:09 GMT
Clients:
 /127.0.0.1:60706[0](queued=0,recved=1,sent=0)

Latency min/avg/max: 0/0/0
Received: 2
Sent: 1
Connections: 1
Outstanding: 0
Zxid: 0x0
Mode: follower
Node count: 4

host B leader

[root@localhost ~]# echo stat | nc 127.0.0.1 2181
Zookeeper version: 3.4.6-1569965, built on 02/20/2014 09:09 GMT
Clients:
 /127.0.0.1:38910[0](queued=0,recved=1,sent=0)

Latency min/avg/max: 0/0/0
Received: 2
Sent: 1
Connections: 1
Outstanding: 0
Zxid: 0x100000000
Mode: leader
Node count: 4

host C follower

[root@localhost ~]# echo stat | nc 127.0.0.1 2181
Zookeeper version: 3.4.6-1569965, built on 02/20/2014 09:09 GMT
Clients:
 /127.0.0.1:38236[0](queued=0,recved=1,sent=0)

Latency min/avg/max: 0/0/0
Received: 2
Sent: 1
Connections: 1
Outstanding: 0
Zxid: 0x100000000
Mode: follower
Node count: 4

踩坑

坑1

WARNING IPv4 forwarding is disabled. Networking will not work

解决办法：

# vi /etc/sysctl.conf
或者
# vi /usr/lib/sysctl.d/00-system.conf
添加如下代码：
    net.ipv4.ip_forward=1

重启network服务
# systemctl restart network

查看是否修改成功
# sysctl net.ipv4.ip_forward

如果返回为“net.ipv4.ip_forward = 1”则表示成功了

坑2

This ZooKeeper instance is not currently serving requests

解决办法：
zookeeper配置中除了 2181 端口还有 2888 和 3888 把这三个端口都开放，然后重加载firewall防火墙配置，重启zookeeper果然集群成功启动。

firewall-cmd --zone=public --add-port=2181/tcp --permanent
firewall-cmd --zone=public --add-port=2888/tcp --permanent
firewall-cmd --zone=public --add-port=3888/tcp --permanent
firewall-cmd --reload

后续进阶

后续将使用swarm + docker-compose 在overlay network 模式下进行一键构建，请听下回分解。