一、所需资源

两台虚拟机：172.20.53.85，172.20.53.87。在两台机器上装上nginx+keepalived

VIP：172.20.53.250

二、安装nginx

1.创建安装目录

mkdir -p /usr/soft

2.进入安装目录并下载nginx

wget http://nginx.org/download/nginx-1.14.0.tar.gz

3.解压

tar -zxvf nginx-1.14.0

4.新建用于安装nginx的文件夹

mkdir nginx

5.将安装路径指定到新建的文件夹

（检查过程可能会因确少某些依赖包报错，根据需要先安装完依赖包再执行）

./configure --prefix=/usr/soft/nginx

6.编译安装

make
make install

三、安装配置keepalived

1.安装

yum install -y keepalived

2.配置

# 172.20.53.85(主机)
$ vim /etc/keepalived/keepalived.conf
vrrp_instance VI_1 {
  state MASTER  #主从标志
  interface ens0  #网卡标志
  virtual_router_id 51 
  priority 100  #权重，主机必须比备机大
  advert_int 1
  authentication {
      auth_type PASS
      auth_pass 1111
  }
  virtual_ipaddress {
      172.20.53.250  #虚拟ip
  }
}
# 172.20.53.87(备机)
$ vim /etc/keepalived/keepalived.conf
vrrp_instance VI_1 {
  state BACKUP
  interface eth0
  virtual_router_id 51
  priority 90
  advert_int 1
  authentication {
      auth_type PASS
      auth_pass 1111
  }
  virtual_ipaddress {
      172.20.53.250
  }
}

3.开启服务

systemctl enable keepalived.service
systemctl start keepalived.service

4.查看虚拟IP是否绑定主机

ip addr show eth0

eth0为网卡标识，可通过ifconfig查看。

 此时虚拟IP已绑定主机，若发现备机也同时绑定了，先关闭防火墙和selinux再重试

5.结合nginx

• 为方便区分主备机，修改一下nginx首页标题

vim /usr/soft/nginx/html/index.html








Welcome to nginx!(85)
If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.

For online documentation and support please refer to
nginx.org.

Commercial support is available at
nginx.com.

Thank you for using nginx.

• 访问虚拟IP

已经访问到主机（85）的nginx。关闭主机（85）的keepalived服务再重新访问，则跳转到备机（87）了

•  高可用思路

　　　可以编写脚本检测主机nginx是否挂掉，当挂掉尝试启动nginx，如果启动失败则关闭keepalived服务，虚拟ip自动跳转到备机

• 添加检测脚本

vim /data/script/nginx_check.sh

A=`ps -C nginx --no-header |wc -l`
if [ $A -eq 0 ];then
  systemctl start nginx
  sleep 2
  if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then
      systemctl stop keepalived.service
  fi
fi

• 配置keepalived配置文件

# 主机(85)配置
global_defs {
 router_id LVS_DEVEL
}
vrrp_script chk_nginx {
  script "/data/script/nginx_check.sh"
  interval 2
  weight -20
}
vrrp_instance VI_1 {
  state MASTER
  interface eth0
  virtual_router_id 51
  priority 100
  advert_int 1
  authentication {
      auth_type PASS
      auth_pass 1111
  }
  track_script {
      chk_nginx
  }
  virtual_ipaddress {
      172.20.53.250
  }
}

# 备机（87）配置
global_defs {
 router_id dreamer1
}
vrrp_script chk_nginx {
  script "/etc/keepalived/nginx_check.sh" 
  interval 2 
  weight -20
}
vrrp_instance VI_1 {
  state BACKUP
  interface eth0
  virtual_router_id 51
  priority 90
  advert_int 1
  authentication {
      auth_type PASS
      auth_pass 1111
  }
  track_script {
      chk_nginx 
  }
  virtual_ipaddress {
      172.20.53.250
  }
}

• 重启并查看keepalived日志

tailf /var/log/messages -n 50 | grep 'Keepalive'

 成功加载脚本