配置Keepalived+Nginx高可用

陳斯托洛夫斯記

发布于 2024-08-07 13:20:51

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发布于 2024-08-07 13:20:51

文章被收录于专栏：XBD

1 Keepalived 简介

1.1、简介

Keepalived 软件起初是专为LVS负载均衡软件设计的，用来管理并监控LVS集群系统中各个服务节点的状态，后来又加入了可以实现高可用的VRRP功能。VRRP是Virtual Router RedundancyProtocol(虚拟路由器冗余协议）的缩写，VRRP出现的目的就是为了解决静态路由单点故障问题的，它能够保证当个别节点宕机时，整个网络可以不间断地运行。

Keepalived软件主要是通过VRRP协议实现高可用功能的。

1.2、Keepalived 故障转移的原理

在 Keepalived 服务正常工作时，主 Master 节点会不断地向备节点发送（多播的方式）心跳消息，用以告诉备节点自己还活看，当主节点发生故障时，就无法发送心跳消息，备节点也就因此无法继续检测到来自主节点的心跳了，于是调用自身的接管程序，接管主节点的 IP 资源及服务。而当主节点恢复时，备节点又会释放自身接管的IP资源及服务，恢复到原来的备用角色。

2 Keepalived 配置文件详解

默认配置文件

[root@iZ8vb9s0vuz4tjn90xrzo2Z ~]# vim /etc/keepalived/keepalived.conf

! Configuration File for keepalived

global_defs {       		# 全局配置
   notification_email {      # 定义报警收件人邮件地址
     acassen@firewall.loc
     failover@firewall.loc
     sysadmin@firewall.loc
   }
   notification_email_from xxx@xxx.com  # 定义报警发件人邮箱
   smtp_server 192.168.200.1    # 邮箱服务器地址
   smtp_connect_timeout 30      # 定义邮箱超时时间
   router_id LVS_DEVEL          # 定义路由标识信息，同局域网内唯一
   vrrp_skip_check_adv_addr
   vrrp_strict
   vrrp_garp_interval 0
   vrrp_gna_interval 0
}

vrrp_instance VI_1 {        # 定义实例
    state MASTER            # 指定keepalived节点的初始状态，可选值为MASTER|BACKUP
    interface eth0          # VRRP实例绑定的网卡接口，用户发送VRRP包
    virtual_router_id 51    # 虚拟路由的ID，同一集群要一致
    priority 100            # 定义优先级，按优先级来决定主备角色，优先级越大越优先
    nopreempt               # 设置不抢占，默认是抢占
    advert_int 1            # 主备通讯时间间隔
    authentication {        # 配置认证
        auth_type PASS      # 认证方式，此处为密码
        auth_pass 1111      # 同一集群中keepalived配置里的此处必须一致，推荐使用8位随机数
    }
    virtual_ipaddress {     # 虚拟 VIP 地址
        192.168.200.16
    }
}

3 Keepalived 实现 Nginx 高可用

3.1 环境

OS	角色	IP	VIP
CentOS7	Master	192.168.1.100	192.168.1.200
CentOS7	Slave	192.168.1.101

3.2 安装配置 Keepalived

在主备节点上安装 Keepalived

yum install keepalived -y

在主备节点上安装 Nginx

yum install nginx -y

配置 Master Keepalived

[root@iZ8vb9s0vuz4tjn90xrzo2Z ~]# vim /etc/keepalived/keepalived.conf

 ! Configuration File for keepalived
 global_defs {
    router_id lb01		# 标识本节点的名称
    vrrp_gna_interval 0
    vrrp_gna_interval 0
 }

 vrrp_script check_nginx {		# 健康检测
   script "/root/check_nginx.sh"
   interval 2				# 间隔多久运行一次检测脚本
   weight -20				# 脚本返回结果非0，优先级减20
   fall 3				# 连续监测失败3次，才认为真的检查失败
 }
 
 vrrp_instance VI_1 {
     state MASTER
     interface eth0
     virtual_router_id 51
     mcast_src_ip 192.168.1.101	# 发送心跳包的源IP，本机IP
     priority 100			# 优先级值越大越高
     nopreempt				# 非抢占模式，需要把state都设置为BACKUP，否则nopreempt无效
     advert_int 1			# 主备之间通讯的间隔秒数，用于判断主节点是否存活
     authentication {
         auth_type PASS
         auth_pass 123456
     }

     track_script {
check_nginx			# 对应上面的检测脚本
     }

     virtual_ipaddress {
         192.168.1.200
     }
 }

配置 Slave Keepalived

[root@iZ8vb9s0vuz4tjn90xrzo2Z ~]# vim /etc/keepalived/keepalived.conf

! Configuration File for keepalived
global_defs {
   router_id lb02		# 标识本节点的名称
   vrrp_garp_interval 0
   vrrp_garp_interval 0
}

vrrp_script check_nginx {
    vrrp_script check_nginx {
    interval 2
    weight -20
    fall 3
}

vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 51
    mcast_src_ip 192.168.1.102	# 发送心跳包的源IP，本机IP
    priority 90
    nopreempt
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }

    track_script {
 check_nginx
    }

    virtual_ipaddress {
        192.168.1.200
    }
}

3.3 Keepalived 监控 Nginx 负载均衡

Keepalived 通过脚本来监控 Nginx 负载均衡状态

在 Master 上编写脚本

创建检测 Nginx 状态脚本

[root@iZ8vb9s0vuz4tjn90xrzo2Z ~]# vim /etc/keepalived/scripts/check_nginx.sh

#!/bin/bash
nginx_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bnginx\b'|wc -l)
if [ $nginx_status -lt 1 ];then
    systemctl stop keepalived
fi

添加执行权限

chmod +x /etc/keepalived/scripts/check_nginx.sh

创建脚本

[root@iZ8vb9s0vuz4tjn90xrzo2Z ~]# vim /etc/keepalived/scripts/notify.sh

#!/bin/bash
VIP=$2
sendmail (){
        subject="${VIP}'s server keepalived state is translate"
        content="`date +'%F %T'`: `hostname`'s state change to master"
        echo $content | mail -s "$subject" xxx@qq.com
}
case "$1" in
  master)
        nginx_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bnginx\b'|wc -l)
        if [ $nginx_status -lt 1 ];then
            systemctl start nginx
        fi
        sendmail
  ;;
  backup)
        nginx_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bnginx\b'|wc -l)
        if [ $nginx_status -gt 0 ];then
            systemctl stop nginx
        fi
  ;;
  *)
        echo "Usage:$0 master|backup VIP"
  ;;
esac

添加执行权限

[root@iZ8vb9s0vuz4tjn90xrzo2Z ~]# chmod +x /etc/keepalived/scripts/notify.sh

在Slave 上缩写脚本

创建脚本

[root@iZ8vb9s0vuz4tjn90xrzo2Z ~]# vim /etc/keepalived/scripts/notify.sh

#!/bin/bash
VIP=$2
sendmail (){
        subject="${VIP}'s server keepalived state is translate"
        content="`date +'%F %T'`: `hostname`'s state change to master"
        echo $content | mail -s "$subject" xxx@qq.com
}
case "$1" in
  master)
        nginx_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bnginx\b'|wc -l)
        if [ $nginx_status -lt 1 ];then
            systemctl start nginx
        fi
        sendmail
  ;;
  backup)
        nginx_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bnginx\b'|wc -l)
        if [ $nginx_status -gt 0 ];then
            systemctl stop nginx
        fi
  ;;
  *)
        echo "Usage:$0 master|backup VIP"
  ;;
esac

添加执行权限

[root@iZ8vb9s0vuz4tjn90xrzo2Z ~]# chmod +x /etc/keepalived/scripts/notify.sh

3.4 配置 Keepalived 加入监控脚本

配置 Master

修改 keepalived.conf 配置文件

[root@iZ8vb9s0vuz4tjn90xrzo2Z ~]# vim /etc/keepalived/keepalived.conf

! Configuration File for keepalived
global_defs {
   router_id lb01
}

vrrp_script nginx_check {
    script "/etc/keepalived/scripts/check_nginx.sh"
    interval 1
    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 123456
    }
    virtual_ipaddress {
        192.168.1.200
    }
    track_script {
        nginx_check
    }
    notify_master "/etc/keepalived/scripts/notify.sh master 192.168.1.200"
    notify_backup "/etc/keepalived/scripts/notify.sh backup 192.168.1.200"
}

启动 Keepalived 服务

systemctl start keepalived

配置 Slave

SLave 无需检测 Nginx 进程是否正常，当升级为 Master 时启动 Nginx，当降为 Slave 时，关闭 Nginx

修改 keepalived.conf 配置文件

[root@iZ8vb9s0vuz4tjn90xrzo2Z ~]# vim /etc/keepalived/keepalived.conf

! Configuration File for keepalived
global_defs {
   router_id lb02
}

vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        192.168.1.200
    }
    notify_master "/etc/keepalived/scripts/notify.sh master 192.168.1.200"
    notify_backup "/etc/keepalived/scripts/notify.sh backup 192.168.1.200"
}

启动 Keepalived 服务