nginx+keepalive主从双机热备+自动切换解决方案

安装

安装必要环境组件及应用

yum -y install gcc openssl-devel popt-devel libnl* kernel-devel ipvsadm libnfnetlink libnfnetlink-devel net-snmp-agent-libs

下载keepalived

wget http://www.keepalived.org/software/keepalived-1.3.5.tar.gz

建立内核软连接

ln -s /usr/src/kernels/$(uname -r)/ /usr/src/linux

解压并进行编译安装

tar xvf keepalived-1.3.5.tar.gz
cd keepalived-1.3.5
./configure
make && make install

为方便以后操作给应用部分文件创建软连接

ln -s /usr/local/etc/keepalived/ /etc/
ln -s /usr/local/etc/sysconfig/keepalived /etc/sysconfig/
ln -s /usr/local/sbin/keepalived /usr/sbin/

==#也可以用yum直接安装==

配置文件解析

/etc/keepalived/keepalived.conf

global_defs {
#                       全局配置模块
            }

vrrp_instance VI_1 {
#                       VRRP配置模块
                    ｝

virtual_server 192.168.111.100 80 {

#                       LVS配置模块
                                    }

配置实例

---

服务器	IP地址	说明
主LVS调度器	192.168.40.11	用于访问WEB服务器负载均衡
副LVS调度器	192.168.40.12	使用Keepalived做双机备份，保证LVS负载均衡稳定性
LVS调度器VIP	192.168.111.100	在Keepalibed配置文件中写入VIP
WEB服务器	192.168.40.135	使用LNMP环境的后端WEB服务器
WEB服务器2	192.168.40.136	使用LAMP环境的后端WEB服务器

配置主LVS服务器 vim /etc/keepalived/keepalived.conf

! Configuration File for keepalived

global_defs {
   notification_email {
     [email protected]
   }
   notification_email_from [email protected]
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id LVS_DEVEL
   vrrp_skip_check_adv_addr
   vrrp_strict
   vrrp_garp_interval 0
   vrrp_gna_interval 0
}

vrrp_instance VI_1 {
    state MASTER
    #主服务器参数
    interface eno16777736
    #网卡接口参数
    virtual_router_id 51
    #VRID，主备服务器要保持一致
    priority 100
    #优先级ID越大优先级越高
    advert_int 1
    #心跳线检验时间
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.111.100
        #VIP地址
    }
}

virtual_server 192.168.111.100 80 {
#LVS服务器地址，使用VIP地址
    delay_loop 6
    #健康检查时间
    lb_algo rr
    #LVS调度算法
    lb_kind DR
    #LVS工作模式
    #persistence_timeout 50
    #保持客户端的请求在这个时间段内全部发到同一个真实服务器，单位为秒
    protocol TCP
    #使用协议

    real_server 192.168.40.135 80 {
    #后端真实WEB服务器1
        weight 1
        #配置节点权重值，值高权重
    TCP_CHECK	{
	connect_timeout=20
	connect_prot 80
	nb_get_retry 3
		}
				  }
    real_server 192.168.40.136 80 {
    #后端真实WEB服务器2
        weight 1
    TCP_CHECK   {
        connect_timeout=20
        connect_prot 80
        nb_get_retry 3
                }
                                  }      
		
}

配置备份服务器 vim /etc/keepalived/keepalived.conf

! Configuration File for keepalived

global_defs {
   notification_email {
     [email protected]
   }
   notification_email_from [email protected]
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id LVS_DEVEL
   vrrp_skip_check_adv_addr
   vrrp_strict
   vrrp_garp_interval 0
   vrrp_gna_interval 0
}

vrrp_instance VI_1 {
    state BACKUP
    #备份服务器参数
    interface ens33
    #网卡接口参数
    virtual_router_id 51
    #VRID，主备服务器要保持一致
    priority 99
    #优先级ID越大优先级越高
    advert_int 1
    #心跳线检验时间
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.111.100
        #VIP地址
    }
}

virtual_server 192.168.111.100 80 {
#LVS服务器地址，使用VIP地址
    delay_loop 6
    #健康检查时间
    lb_algo rr
    #LVS调度算法
    lb_kind DR
    #LVS工作模式
    #persistence_timeout 50
    #保持客户端的请求在这个时间段内全部发到同一个真实服务器，单位为秒
    protocol TCP
    #使用协议

    real_server 192.168.40.135 80 {
    #后端真实WEB服务器1
        weight 1
        #配置节点权重值，值高权重
    TCP_CHECK	{
	connect_timeout=20
	connect_prot 80
	nb_get_retry 3
		}
				  }
    real_server 192.168.40.136 80 {
    #后端真实WEB服务器2
        weight 1
    TCP_CHECK   {
        connect_timeout=20
        connect_prot 80
        nb_get_retry 3
                }
                                  }      
		
}

配置完成启用keepalived服务，并加入开机自启

/usr/sbin/keepalived
echo '/usr/sbin/keepalived' >> /etc/rc.local

==#若用systemctl启动，提示PID file /usr/local/var/run/keepalived.pid not readable (yet?) after start.无法启用服务，可手动建立PID文件，并写入进程值（ps aux查看keepalived进程）再启动==

此时，就可以测试Keepalived高可用性了，可以用ip add查看主LVS服务器是否有192.168.111.100公网VIP地址，如果有再看备用LVS服务器是否有，备用服务器应该是没有的，把主LVS服务器的keepalived服务停用，再看备用LVS如果有公网VIP地址，说明Keepalived可以使用即可往下边看。

---

WEB服务器配置

两个WEB服务器分别都添加回环VIP地址 cat /etc/sysconfig/network-scripts/ifcfg-lo:0

DEVICE=lo:0
BOOTPROTO=static
IPADDR=192.168.111.100
NETMASK=255.255.255.0
NETWORK=192.168.111.10
ONBOOT=yes

多个设备均被设置了VIP地址，为防止地址冲突，修改内核ARP参数 ==#注意此处eth0网卡，部分根据不同主机网卡信息变动，如果想永久生效还需要将网卡配置信息写入到配置文件中==

#!/bin/bash
#description: config realserver lo  and  apply noarp

WEB_VIP=192.168.111.100 #填写对应的公网VIP地址
. /etc/rc.d/init.d/functions

case "$1" in

start)
   ifconfig lo:0 $WEB_VIP netmask 255.255.255.255 broadcast $WEB_VIP
   /sbin/route add -host $WEB_VIP dev lo:0
   echo "1" >/proc/sys/net/ipv4/conf/lo/arp_ignore
   echo "2" >/proc/sys/net/ipv4/conf/lo/arp_announce
   echo "1" >/proc/sys/net/ipv4/conf/all/arp_ignore
   echo "2" >/proc/sys/net/ipv4/conf/all/arp_announce
   echo "1" > /proc/sys/net/ipv4/conf/eth0/arp_ignore
   echo "2" > /proc/sys/net/ipv4/conf/eth0/arp_announce
   echo "1" > /proc/sys/net/ipv4/conf/default/arp_ignore
   echo "2" > /proc/sys/net/ipv4/conf/default/arp_announce
   sysctl -p >/dev/null 2>&1
   echo "RealServer Start OK"
   ;;
stop)
   ifconfig lo:0 down
   route del $WEB_VIP >/dev/null 2>&1
   echo "0" >/proc/sys/net/ipv4/conf/lo/arp_ignore
   echo "0" >/proc/sys/net/ipv4/conf/lo/arp_announce
   echo "0" >/proc/sys/net/ipv4/conf/all/arp_ignore
   echo "0" >/proc/sys/net/ipv4/conf/all/arp_announce
   echo "0" > /proc/sys/net/ipv4/conf/eth0/arp_ignore
   echo "0" > /proc/sys/net/ipv4/conf/eth0/arp_announce
   echo "0" > /proc/sys/net/ipv4/conf/default/arp_ignore
   echo "0" > /proc/sys/net/ipv4/conf/default/arp_announce
   echo "RealServer Stoped"
   ;;
status)
       # Status of LVS-DR real server.
       islothere=`/sbin/ifconfig lo:0 | grep $WEB_VIP`
       isrothere=`netstat -rn | grep "lo:0" | grep $WEB_VIP`
       if [ ! "$islothere" -o ! "isrothere" ];then
         # Either the route or the lo:0 device
         # not found.
         echo "LVS-DR real server Stopped."
       else
         echo "LVS-DR Running."
       fi
;;
*)
       # Invalid entry.
       echo "$0: Usage: $0 {start|status|stop}"
       exit 1
;;
esac
exit 0

开启路由转发功能

sed -i '/ip_forward/s/0/1/' /etc/sysctl.conf

重新加载sysctl文件

sysctl -p

---

核查检验

在主备Keepalived服务器上查看ipvsadm此时状态

ipvsadm -Ln

Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  192.168.111.100:80 rr
  -> 192.168.40.135:80            Route   1      0          0         
  -> 192.168.40.136:80            Route   1      0          0         

此时就可以访问VIP地址测试结果了

注：主写配置信息，测试服务因图片总是失效故截取至此，可自行依照案例做服务测试