用Keepalived搭建高可用集群

一、集群介绍

1、根据功能划分为两大类：高可用和负载均衡

2、高可用：一台工作，另一台冗余，当一台服务器故障宕机时，另一台服务器提供服务。开源软件有heartbeat，keepalived.

3、负载均衡：有一台服务器做分发器，负责把用户的请求发送给后端处理，其他的服务器给用户提供服务。开源软件有LVS，keepalived,haproxy,nginx.商业的有F5，Netscaler.

二、keepalived介绍

1、keepalived 是采用VRRP协议实现高可用。keepalived 有三个模块，core ，check，vrrp。core模块是keepalived的核心，负责主进程启动，维护和全局模块的加载和解析，check模块负责健康检查，vrrp模块用来实现VRRP协议。

三、用keepalived搭建高可用集群。

1、为两台机器安装keepalived

yum install -y keepalived

2、为两台机器安装nginx,其中IP为130的主机已经在之前安装过，只需为另一台安装

yum install -y nginx

用Keepalived搭建高可用集群

3、编辑130主机的keepalived的配置文件 vim /etc/keepalived/keepalived.conf

1)首先清空keepalived.conf

> keepalived.conf

2)加入以下内容：

global_defs {

notification_email {

aming @aminglinux.com

}

notification_email_from root @aminglinux.com

smtp_server 127.0.0.1

smtp_connect_timeout 30

router_id LVS_DEVEL

}

vrrp_script chk_nginx {

script "/usr/local/sbin/check_ng.sh"

interval 3

}

vrrp_instance VI_1 {

state MASTER

interface ens33

virtual_router_id 51

priority 100

advert_int 1

authentication {

auth_type PASS

auth_pass aminglinux>com

}

virtual_ipaddress {

192.168.134.100

}

track_script {

chk_nginx

}

4、定义130主机上的监控脚本 vim /usr/local/sbin/check_ng.sh

 
  #!/bin/bash 
 
   d=`date --date today +%Y%m%d_%H:%M:%S` 
 
   n=`ps -C nginx --no-heading|wc 
  -l` 
 
  if [ $n -eq "0" ]; then 
 
   /etc/init.d/nginx start 
 
   n2=`ps -C nginx --no-heading|wc 
  -l` 
 
  if [ $n2 -eq "0" ]; then 
 
  echo "$d nginx down,keepalived will stop" >> /var/log/check_ng.log 
 
   systemctl stop keepalived 
 
  fi 
 
  fi

5、给 check_ng.sh 权限，启动keepalived服务

chmod 755 /usr/local/sbin/check_ng.sh

systemctl start keepalived

6、停止nginx服务，查看nginx是否启动，查看日志 /var/log/message 和 IP ip add 。

7、关闭主从机器的防火墙和 SELinux

systemctl stop firewalld

setenforce 0

8、配置IP 为150的从服务器，

1）先清空keepalived.conf文件

> /etc/keepalived/keepalived.conf

2)添加以下内容:

   global_defs { 
 
   notification_email { 
 
   aming 
  @aminglinux.com 
 
   } 
 
   notification_email_from root 
  @aminglinux.com 
 
   smtp_server 
  127.0.0.1 
 
   smtp_connect_timeout 
  30 
 
   router_id LVS_DEVEL 
 
   } 
 
   vrrp_script chk_nginx { 
 
   script 
  "/usr/local/sbin/check_ng.sh" 
 
   interval 
  3 
 
   } 
 
   vrrp_instance VI_1 { 
 
   state BACKUP 
 
  interface ens33 
 
  virtual_router_id 51 
 
  priority 90 
 
  advert_int 1 
 
  authentication { 
 
   auth_type PASS 
 
   auth_pass aminglinux>com 
 
   } 
 
   virtual_ipaddress { 
 
  192.168.134.100 
 
   } 
 
   track_script { 
 
   chk_nginx 
 
   } 
 
   } 
 
   9、编辑定义150的监控脚本 
 
   #!/bin/bash 
  
    d=`date --date today +%Y%m%d_%H:%M:%S` 
  
    n=`ps -C nginx --no-heading|wc 
   -l 
  
   if [ 
   $n 
   -eq 
   "0" ]; 
   then 
  
    systemctl start nginx 
  
    n2=`ps -C nginx --no-heading|wc 
   -l` 
  
   if [ 
   $n2 
   -eq 
   "0" ]; 
   then 
  
   echo 
   "$d nginx down,keepalived will stop" >> /var/ 
   log/check_ng.log 
  
    systemctl stop keepalived 
  
   fi 
  
   fi