Nginx+keepalived双机热备踩坑实践

先准备好两台服务器上的nginx

更改/usr/local/nginx/html/index.html，增加ip的显示

keepalived下载及编译安装

wget http://www.keepalived.org/software/keepalived-2.0.13.tar.gz
tar -xzvf keepalived-2.0.13.tar.gz
./configure验证配置
出现提示
configure: error:
  !!! OpenSSL is not properly installed on your system. !!!
  !!! Can not include OpenSSL headers files.            !!!

yum -y install openssl-devel解决

再次./configure验证配置
又提示
*** WARNING - this build will not support IPVS with IPv6. Please install libnl/libnl-3 dev libraries to support IPv6 with IPVS.

按照提示安装libnl及libnl-devel

yum -y install libnl libnl-devel

./configure没有问题
make && make install编译安装

更改配置
vim /etc/keepalived/keepalived.conf

 主keepalived配置

! Configuration File for keepalived

vrrp_script check_nginx_alive {
    script "/data/check_nginx_alive.sh" #检测nginx进程是否存在的脚本
    interval 2 #每2s检查一次
    weight -10 

}

global_defs {
   notification_email {
     [email protected]
     [email protected]
     [email protected]
   }
   notification_email_from [email protected]
   smtp_server 192.168.200.1
   smtp_connect_timeout 30
   router_id LVS_DEVEL_1 #标识，这个需要全局唯一，其他邮件什么的默认不改
   vrrp_skip_check_adv_addr
   #vrrp_strict
   vrrp_garp_interval 0
   vrrp_gna_interval 0
}

vrrp_instance VI_1 {
    state MASTER #主从设置 MASTER/BACKUP
    interface ens33 #网卡名称
    virtual_router_id 51 #master和slave的值需要相同
    priority 101 #优先级，从节点 配置，需要小于主节点
    advert_int 1
    authentication {  #这是主从之间的认证，需要相同
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.76.100  #设置的虚拟ip地址
    }
    track_script {
        check_nginx_alive   #调用的脚本 vrrp_script后面的名称
    }
}

virtual_server 192.168.76.100 80 {
    delay_loop 6
    lb_algo rr
    lb_kind NAT
#    persistence_timeout 50
    protocol TCP

    real_server 192.168.76.130 80 {#实际的服务地址
        weight 1
        TCP_CHECK {
           connect_timeout 3
           nb_get_retry 3
           delay_before_retry 3
           connect_port 80
        }
    }
}

脚本check_nginx_alive.sh（检测nginx进程是否存在，若不存在关闭本机上的keepalived,切换到从服务器）

#!/bin/bash

A=`ps -C nginx --no-header |wc -l`
if [ $A -eq 0 ]
then
echo 'nginx server is died'
killall keepalived
else
echo 'nginx server is alived do nothing'
fi

重启keepalived

 systemctl restart keepalived
ip addr

从keepalived配置

! Configuration File for keepalived

vrrp_script check_nginx_alive {
    script "/data/check_nginx_alive.sh"
    interval 2
    weight -10

}

global_defs {
   notification_email {
     [email protected]
     [email protected]
     [email protected]
   }
   notification_email_from [email protected]
   smtp_server 192.168.200.1
   smtp_connect_timeout 30
   router_id LVS_DEVEL_2
#   vrrp_skip_check_adv_addr
#   vrrp_strict
#   vrrp_garp_interval 0
#   vrrp_gna_interval 0
}

vrrp_instance VI_1 {
    state BUCKUP
    interface ens33
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.76.100
    }
    track_script {
        check_nginx_alive
    }
}

virtual_server 192.168.76.100 80 {
    delay_loop 6
    lb_algo rr
    lb_kind NAT
#    persistence_timeout 50
    protocol TCP

    real_server 192.168.76.129 80 {
        weight 1
        TCP_CHECK {
           connect_timeout 3
          # nb_get_retry 3
           delay_before_retry 3
           connect_port 80
        }
    }
}

可以看到，已经多个虚拟ip

访问192.168.76.100看看 

关闭130上的nginx

查看日志tail -100f /var/log/messages

 keepalived已关闭

此时访问192.168.76.100

vip偏移到了129上。

最后总结一下错误经验

一、首先keepalived的配置文件是放在/etc/keepalived/keepalived.conf，启动失败看日志才发现

二、启动成功后，vip生成成功后，访问不了vip,也ping不通，查询发现是vrrp_strict没有注释

 

对于Keepalived中Master和Backup角色选举策略还不太清楚，学习完成后再来分享

##############################20190418更新

virtual_server配多个，可以支持虚拟路径映射其他的端口

参考文章：http://www.linuxde.net/2013/04/13381.html