Linux配置Keepalived,实现nginx主备切换

一、下载Keepalived

1、下载依赖软件

yum install -y gcc
yum install -y openssl-devel
yum install -y libnl libnl-devel
yum install -y libnfnetlink-devel
yum install -y net-tools
yum install -y vim wget

2、下载压缩包到/usr/local（我以keepalived-2.0.10为例），解压安装

  cd /use/local/src
  tar -zxvf keepalived-2.0.10.tar.gz
  mv keepalived-2.0.10 keepalived 　　# 修改文件名
  cd /use/local/keepalived/
  ./configure　　　　　　　　
  make && make install

3、将配置文件复制到默认路径

mkdir /etc/keepalived
cp /usr/local/keepalived/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
cp /usr/local/keepalived/keepalived/etc/init.d/keepalived /etc/rc.d/init.d/         # 启动文件，用于开机自启
cp /usr/local/keepalived/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
cp /usr/local/sbin/keepalived /usr/sbin/

4、设置开机自启

chkconfig keepalived on
service keepalived start   #启动服务
service keepalived stop    #停止服务
service keepalived restart #重启服务

二、创建随Nginx服务停止而停止的脚本（主备两台都要配置）

1、在/etc/keeplived路径下创建check_nginx.sh脚本文件，内容如下：

#!/bin/bash
A=`ps -C nginx --no-header | wc -l`
if [ $A -eq 0 ];then
service keepalived stop
fi

2、修改该脚本的权限

chmod 777 check_nginx.sh

3、修改/etc/keepalived下的keepalived.conf如下（红色部分）

三、脑裂

原因：如果你用的是firewall防火墙，考虑是Firewall没配置支持vrrp协议，方法如下：

firewall-cmd --direct --permanent --add-rule ipv4 filter INPUT 0 --destination 224.0.0.18 --protocol vrrp -j ACCEPT
firewall-cmd --direct --permanent --add-rule ipv4 filter OUTPUT 0 --destination 224.0.0.18 --protocol vrrp -j ACCEPT
firewall-cmd --reload

Keepalived使用vrrp组播，默认地址是224.0.0.18，因此要配置防火墙放过。

四、其他

1、keepalived配置文件参考：https://www.cnblogs.com/kevingrace/p/6248941.html

2、如果加入LVS，参考：https://lupengfei.blog.csdn.net/article/details/86514445