keepalived对nginx进行高可用搭建及原理详解

[root@localhost ~]# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {                                     #全局定义部分
    notification_email {                          #设置报警邮件地址，可设置多个
        acassen@firewall.loc                      #接收通知的邮件地址
    }
    notification_email_from test0@163.com         #设置 发送邮件通知的地址
    smtp_server smtp.163.com                      #设置 smtp server 地址，可是ip或域名.可选端口号 （默认25）
    smtp_connect_timeout 30                       #设置 连接 smtp server的超时时间
    router_id LVS_DEVEL                           #主机标识，用于邮件通知
    vrrp_skip_check_adv_addr
    vrrp_strict                                   #严格执行VRRP协议规范，此模式不支持节点单播
    vrrp_garp_interval 0
    vrrp_gna_interval 0
    script_user keepalived_script                 #指定运行脚本的用户名和组。默认使用用户的默认组。如未指定，默认为keepalived_script 用户，如无此用户，则使用root
    enable_script_security                        #如过路径为非root可写，不要配置脚本为root用户执行。
}
vrrp_instance VI_1 {                              #vrrp 实例部分定义，VI_1自定义名称
    state MASTER                                  #指定 keepalived 的角色，必须大写 可选值：MASTER|BACKUP
    interface ens33                               #网卡设置，lvs需要绑定在网卡上，realserver绑定在回环口。区别：lvs对访问为外，realserver为内不易暴露本机信息
    virtual_router_id 51                          #虚拟路由标识，是一个数字，同一个vrrp 实例使用唯一的标识，MASTER和BACKUP 的 同一个 vrrp_instance 下 这个标识必须保持一致
    priority 100                                  #定义优先级，数字越大，优先级越高。
    advert_int 1                                  #设定 MASTER 与 BACKUP 负载均衡之间同步检查的时间间隔，单位为秒，两个节点设置必须一样
    authentication {                              #设置验证类型和密码，两个节点必须一致
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {                           #设置虚拟IP地址，可以设置多个虚拟IP地址，每行一个
        192.168.119.130
    }
    track_script {                                #脚本监控状态
        chk_nginx_service                         #可加权重，但会覆盖声明的脚本权重值。chk_nginx_service weight -20
    }
        notify_master "/etc/keepalived/start_haproxy.sh start"  #当前节点成为master时，通知脚本执行任务
        notify_backup "/etc/keepalived/start_haproxy.sh stop"   #当前节点成为backup时，通知脚本执行任务
        notify_fault  "/etc/keepalived/start_haproxy.sh stop"   #当当前节点出现故障，执行的任务;
}
virtual_server 192.168.119.130 80  {          #定义RealServer对应的VIP及服务端口，IP和端口之间用空格隔开
    delay_loop 6                              #每隔6秒查询realserver状态
    lb_algo rr                                #后端调试算法（load balancing algorithm）
    lb_kind DR                                #LVS调度类型NAT/DR/TUN
    #persistence_timeout 60                   同一IP的连接60秒内被分配到同一台realserver
    protocol TCP                              #用TCP协议检查realserver状态
    real_server 192.168.119.120 80 {
        weight 1                              #权重，最大越高，lvs就越优先访问
        TCP_CHECK {                           #keepalived的健康检查方式HTTP_GET | SSL_GET | TCP_CHECK | SMTP_CHECK | MISC
            connect_timeout 10                #10秒无响应超时
            retry 3                           #重连次数3次
            delay_before_retry 3              #重连间隔时间
            connect_port 80                   #健康检查realserver的端口
        }
    }
}
}

[root@localhost ~]# yum -y install nginx
[root@localhost ~]# cd /usr/share/nginx/html/
[root@localhost html]# mv index.html index.html.back
[root@localhost html]# echo "I am 192.168.73.136" > index.html
[root@localhost html]# systemctl start nginx
[root@localhost html]# curl 192.168.73.136
I am 192.168.73.136

[root@localhost ~]# yum install keepalived -y
[root@localhost ~]# rpm -ql keepalived
/etc/keepalived
/etc/keepalived/keepalived.conf  # 主配置文件
/etc/sysconfig/keepalived
/usr/bin/genhash
/usr/lib/systemd/system/keepalived.service
/usr/libexec/keepalived
/usr/sbin/keepalived

[root@localhost ~]# vim /etc/keepalived/check_port.sh
#!/bin/bash
#keepalived 监控端口脚本
#使用方法：
#在keepalived的配置文件中
#vrrp_script check_port {#创建一个vrrp_script脚本,检查配置
#    script "/etc/keepalived/check_port.sh 80" #配置监听的端口
#    interval 2 #检查脚本的频率,单位（秒）
#}
CHK_PORT=$1
if [ -n "$CHK_PORT" ];then
        PORT_PROCESS=`ss -lnt|grep $CHK_PORT|wc -l`
        if [ $PORT_PROCESS -eq 0 ];then
                echo "Port $CHK_PORT Is Not Used,End."
                exit 1
        fi
else
        echo "Check Port Cant Be Empty!"
fi
[root@localhost ~]# chmod  +x /etc/keepalived/check_port.sh

[root@localhost ~]# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
   router_id 192.168.73.136
}
vrrp_script chk_nginx {
    script "/etc/keepalived/check_port.sh 80"
    interval 2
    weight -20
}
vrrp_instance VI_1 {
    state MASTER
    interface ens33
    virtual_router_id 251
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 11111111
    }
    track_script {
         chk_nginx
    }
    virtual_ipaddress {
        192.168.73.100
    }
}

! Configuration File for keepalived
global_defs {
        router_id 192.168.73.135
}
vrrp_script chk_nginx {
        script "/etc/keepalived/check_port.sh 80"
        interval 2
        weight -20
}
vrrp_instance VI_1 {
        state BACKUP
        interface ens33
        virtual_router_id 251
        priority 90
        advert_int 1
        authentication {
                auth_type PASS
                auth_pass 11111111
        }
        track_script {
                chk_nginx
        }
        virtual_ipaddress {
                192.168.73.100
        }
}

[root@localhost ~]]systemctl start keepalived && systemctl enable keepalive

[root@localhost keepalived]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:6f:74:0a brd ff:ff:ff:ff:ff:ff
    inet 192.168.73.136/24 brd 192.168.73.255 scope global noprefixroute ens33
       valid_lft forever preferred_lft forever
    inet 192.168.73.100/32 scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::af0e:a936:d997:18da/64 scope link noprefixroute
       valid_lft forever preferred_lft forever

# 关闭主nginx
[root@localhost ~]# systemctl stop nginx
# 查看备上的IP信息，我们发现vip已经偏移到备机上了
[root@localhost ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:6f:74:0a brd ff:ff:ff:ff:ff:ff
    inet 192.168.73.136/24 brd 192.168.73.255 scope global noprefixroute ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::af0e:a936:d997:18da/64 scope link noprefixroute
       valid_lft forever preferred_lft forever

[root@zdd211-11 ~]# vim /etc/keepalived/check_keepalived.sh
#!/bin/bash
NGINX_SBIN="which nginx"
NGINX_PORT=80
function check_nginx(){
     NGINX_STATUS="nmap localhost -p ${NGINX_PORT} | grep "80/tcp open" | awk '{print $2}'"
     NGINX_PROCESS="ps -ef | grep nginx|grep -v grep|wc -l"
}
check_nginx
if [ "$NGINX_STATUS" != "open"  -o  $NGINX_PROCESS -lt 2 ]
then
    ${NGINX_SBIN} -s stop
    ${NGINX_SBIN}
    sleep 3
    check_nginx
    if [ "$NGINX_STATUS" != "open"  -o  $NGINX_PROCESS -lt 2 ];then
        systemctl stop keepalived
    fi
 fi
 [root@localhost ~]# chmod  +x /etc/keepalived/check_port.sh

[root@localhost ~]# yum install nmap -y

[root@localhost ~]# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
   router_id 192.168.73.136
}
vrrp_script chk_nginx {
    script "/etc/keepalived/check_port.sh 80"
    interval 2
    weight -20
}
vrrp_script chk_nginx {
    script "/etc/keepalived/check_keepalive.sh" # 脚本路径
    interval 2                                  # 执行时间间隔
    weight -5                                   # 计算权重值，脚本结果导致的优先级变更，检测失败（脚本返回非0）则优先级 -5
    fall 3                                      # 检测连续3次失败才算确定是真失败。会用weight减少优先级（1-255之间）
    rise 2                                      # 检测2次成功就算成功。但不修改优先级
vrrp_instance VI_1 {
    state MASTER
    interface ens33
    virtual_router_id 251
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 11111111
    }
    track_script {
         chk_nginx
    }
    virtual_ipaddress {
        192.168.73.100
    }
}

! Configuration File for keepalived
global_defs {
        router_id 192.168.73.135
}
vrrp_script chk_nginx {
    script "/etc/keepalived/check_keepalive.sh"
    interval 2                     # 执行时间间隔
    weight -5                      # 计算权重值，脚本结果导致的优先级变更，检测失败（脚本返回非0）则优先级 -5
    fall 3                         # 检测连续3次失败才算确定是真失败。会用weight减少优先级（1-255之间）
    rise 2                         # 检测2次成功就算成功。但不修改优先级
vrrp_instance VI_1 {
        state BACKUP
        interface ens33
        virtual_router_id 251
        priority 90
        advert_int 1
        authentication {
                auth_type PASS
                auth_pass 11111111
        }
        track_script {
                chk_nginx
        }
        virtual_ipaddress {
                192.168.73.100
        }
}

[root@localhost ~]# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
   router_id 192.168.73.136
}
vrrp_script chk_nginx {
    script "/etc/keepalived/check_keepalive.sh" # 脚本路径
    interval 2                                  # 执行时间间隔
    weight -5                                   # 计算权重值，脚本结果导致的优先级变更，检测失败（脚本返回非0）则优先级 -5
    fall 3                                      # 检测连续3次失败才算确定是真失败。会用weight减少优先级（1-255之间）
    rise 2                                      # 检测2次成功就算成功。但不修改优先级
}
vrrp_instance VI_1 {
    state MASTER
    interface ens33
    virtual_router_id 251
    priority 100
    advert_int 1
    nopreempt    ##不抢VIP 机制
    authentication {
        auth_type PASS
        auth_pass 11111111
    }
    track_script {
         chk_nginx
    }
    virtual_ipaddress {
        192.168.73.100
    }
}

global_defs
{
  ``router_id LVS_19
  ``vrrp_mcast_group4 224.0.0.19` `#指定多播地址
}