Centos 7+Docker+Nginx+KeepAlived实现高可用

Docker安装全过程：

拉取centos7镜像：

docker pull centos:7

创建容器：

docker run -it -d --name centos1 -d centos:7

进入容器：

docker exec -it centos1 bash

安装一些常用工具：

yum update
yum install -y vim wget gcc-c++ pcre pcre-devel zlib zlib-devel openssl openssl--develyum popt-develyum initscripts net-tools

打包镜像,方便以后使用：

docker commit -a 'cfh' -m 'centos with common tools' centos1 centos_base

删除以前创建的镜像：

docker rm -f centos1

创建新的镜像：

#容器内需要使用systemctl服务，需要加上/usr/sbin/init
docker run -it --name centos7_1 -d --privileged centos_base /usr/sbin/init
docker exec -it centos7_1 bash

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

下载并安装keepalived：

wget http://www.keepalived.org/software/keepalived-1.2.18.tar.gz
# 解压到/usr/local下
tar -zxvf keepalived-1.2.18.tar.gz -C /usr/local/
# 安装https需要的包
yum install -y openssl openssl-devel
# 编译keepalived
cd /usr/local/keepalived-1.2.18/ && ./configure --prefix=/usr/local/keepalived
make && make install

# 将keepalived 安装成系统服务
cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
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

systemctl start keepalived.service 
# 如果启动报错则执行下面的命令
cd /usr/sbin/
rm -f keepalived 
cp /usr/local/keepalived/sbin/keepalived /usr/sbin/

修改keepalived配置文件：

# 备个份
cp /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.backup
vim /etc/keepalived/keepalived.conf
# 文件配置如下：

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
  }
}

编辑检测脚本：

vim /etc/keepalived/nginx_check.sh
# 脚本如下：

#!/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

添加执行权限：

chmod +x /etc/keepalived/nginx_check.sh

开启keepalived(开启过则需要重启启动一下)：

systemctl enable keepalived.service
# 开启keepalived
systemctl start keepalived.service
# 检查虚拟IP是否绑定成功
curl 172.17.0.100(确保nginx运行) 或者 ip a(现在是在容器里面)

重新打包镜像，环境都已经配置好了，方便以后使用：

docker commit -a 'cfh' -m 'centos with keepalived and nginx' centos7_1 centos_nginx_keepalived

删除所有容器：

docker rm -f `docker ps -a -q`

创建master：

docker run --privileged -tid --name centos_master --restart=always centos_nginx_keepalived /usr/sbin/init
docker exec -it centos_master bash

# 修改index.html让他们看起来不太一样：
vim /usr/share/nginx/html/index.html

创建slave：

docker run --privileged -tid --name centos_slave --restart=always centos_nginx_keepalived /usr/sbin/init
docker exec -it centos_slave bash

# 更改keepalived的配置文件，把priority改小一点，当前是从机
vim /etc/keepalived/keepalived.conf,当前图是 master的(偷个懒)，slave改到80

# 修改index.html让他们看起来不太一样，当前是salve节点：
vim /usr/share/nginx/html/index.html

重新加载(nginx没重启的重启一下，主从机都执行一下)：

systemctl daemon-reload
systemctl restart keepalived.service

测试：

curl 172.17.0.100

进入master，主动停掉keepalived，再执行：

curl 172.17.0.100

现在返回的就是slave的信息了

最后

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