Docker+keepalived+nginx实现主从热备的方法示例

前言

为解决单点故障，我们需要配置主从热备方案，服务器数量有限，故使用Docker模拟安装配置。

本次配置默认已经安装了Docker。

配置环境:centos7 64位

docker版本:Docker version 17.12.1-ce, build 7390fc6


1，拉取centos7镜像

docker pull centos:7
2,创建容器

docker run -it -d –name centos1 -d centos:7
3,进入容器centos1

docker exec -it centos1 bash
4,安装常用工具

yum updateyum install -y vimyum install -y wgetyum install -y gcc-c++ yum install -y pcre pcre-devel yum install -y zlib zlib-devel yum install -y openssl openssl–develyum install -y popt-develyum install -y initscripts

yum install -y net-tools
5，将容器打包成新的镜像，以后直接以该镜像创建容器

docker commit -a ‘cfh’ -m ‘centos with common tools’ centos1 centos_base
6,删除之前创建的centos1 容器，重新以基础镜像创建容器，安装keepalived+nginx

docker rm -f centos1

#容器内需要使用systemctl服务，需要加上/usr/sbin/init

docker run -it –name centos_temp -d –privileged centos_base /usr/sbin/init

docker exec -it centos_temp bash

作者：江湖救急

链接：https://juejin.im/post/5dc517386fb9a04a9272110b

来源：掘金

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7,安装nginx

#使用yum安装nginx需要包括Nginx的库，安装Nginx的库

rpm -Uvh http://nginx.org/packages/centos/7/noarch/RPMS/nginx-release-centos-7-0.el7.ngx.noarch.rpm

# 使用下面命令安装nginx

yum install -y nginx

#启动nginx

systemctl start nginx.service

#查看是否启动成功,出现nginx欢迎界面表示安装成功

curl 172.17.0.2
8,安装keepalived

1.下载keepalived wget http://www.keepalived.org/software/keepalived-1.2.18.tar.gz

2.解压安装：tar -zxvf keepalived-1.2.18.tar.gz -C /usr/local/

3.下载插件openssl yum install -y openssl openssl-devel（需要安装一个软件包）

4.开始编译keepalivedcd /usr/local/keepalived-1.2.18/ && ./configure –prefix=/usr/local/keepalived

5.make一下 make && make install


9,将keepalived 安装成系统服务

mkdir /etc/keepalivedcp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/然后复制keepalived脚本文件：cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/ln -s /usr/local/sbin/keepalived /usr/sbin/可以设置开机启动：chkconfig keepalived on，到此我们安装完毕!

#若启动报错，则执行下面命令

cd /usr/sbin/

rm -f keepalived

cp /usr/local/keepalived/sbin/keepalived /usr/sbin/

#常用命令

systemctl daemon-reload 重新加载systemctl enable keepalived.service 设置开机自动启动systemctl disable keepalived.service 取消开机自动启动systemctl start keepalived.service 启动systemctl stop keepalived.service停止systemctl status keepalived.service 查看服务状态
10,修改/etc/keepalived/keepalived.conf文件

#备份配置文件

cp /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.backup

rm -f keepalived.conf

vim keepalived.conf

#配置文件如下

vrrp_script chk_nginx {

  script “/etc/keepalived/nginx_check.sh”

  interval 2

  weight -20

}

vrrp_instance VI_1 {

  state MASTER

  interface eth0

  virtual_router_id 121

  mcast_src_ip 172.17.0.6

  priority 100

  nopreempt

  advert_int 1

  authentication {

    auth_type PASS

    auth_pass 1111

  }

  track_script {

    chk_nginx

  }

  virtual_ipaddress {

    172.17.0.100

  }

}
11,添加心跳检测文件

vim nginx_check.sh

#以下是脚本内容

#!/bin/bash

A=`ps -C nginx –no-header |wc -l`

if [ $A -eq 0 ];then

  /usr/local/nginx/sbin/nginx

  sleep 2

  if [ `ps -C nginx –no-header |wc -l` -eq 0 ];then

    killall keepalived

  fi

fi
12,给脚本赋予执行权限

chmod +x nginx_check.sh
13,设置开机启动

systemctl enable keepalived.service

#开启keepalived

systemctl start keepalived.service


14,检测虚拟IP是否成功,在宿主机里面执行下面命令，如果出现nginx欢迎界面表示成功

curl 172.17.0.100
15，将centos_temp 容器重新打包成镜像，然后利用这个新镜像再创建两个容器，实现热备效果

docker commit -a ‘cfh’ -m ‘centos with keepalived nginx’ centos_temp centos_kn
16,删除所有容器

docker rm -f `docker ps -a -q`
17，用centos_kn 镜像创建主服务器容器

docker run –privileged -tid –name centos_master –restart=always centos_kn /usr/sbin/init

docker exec -it centos_master bash
18，修改centos_master里面nginx 欢迎页,

vim /usr/share/nginx/html/index.html

19,创建从服务器容器

docker run –privileged -tid –name centos_slave –restart=always centos_kn /usr/sbin/init

docker exec -it centos_slave bash

#修改keepalived.conf 配置文件,主要是state和priority两个参数的调整，其中master节点的priority值一定要比slave大才行

vrrp_script chk_nginx {

  script “/etc/keepalived/nginx_check.sh”

  interval 2

  weight -20

}

vrrp_instance VI_1 {

  state SLАVE

  interface eth0

  virtual_router_id 121

  mcast_src_ip 172.17.0.6

  priority 80

  nopreempt

  advert_int 1

  authentication {

    auth_type PASS

    auth_pass 1111

  }

  track_script {

    chk_nginx

  }

  virtual_ipaddress {

    172.17.0.100

  }

}
20,修改完成之后重新加载

systemctl daemon-reload

systemctl restart keepalived.service
21,修改nginx欢迎页（若nginx没启动则执行 systemctl start nginx.service）

vim /usr/share/nginx/html/index.html

22,测试

A> 分别在宿主机，centos_master,centos_slave中进行一下命令测试,如果显示都为Master的欢迎页面，说明配置成功1/3

curl 172.17.0.100B> 此时停止centos_master容器( docker stop centos_master )，保留centos_slave容器，执行以下命令,若切换到Slave页面，则说明keepalived配置成功2/3

curl 172.17.0.100C> 重启centos_master 容器，此时执行以下命令,看是从Slave切换到了Master,如果切换成功，说明我们配置到此成功了。

curl 172.17.0.100说明，测试过程中，重启容器之后，nginx没有启动，需要进入容器启动一下，不然访问不到Master页面了，但是可以Ping通。

执行下面命令，配置nginx随机启动,这样不用每次重启容器还需要手动启动nginx

chkconfig nginx on以上就是整个配置过程，希望对大家的学习有所帮助，也希望大家多多支持共生网络。