Nginx+keepalived负载均衡篇

Question

由于nginx的url hash功能可以很好的提升squid的性能，所以我把squid前端的负载均衡器更换为nginx，但是一台nginx就形成了单点，现在使用keepalived来解决这个问题，keepalived的故障转移时间很短，而且配置简单，这也是选择keepalived的一个主要原因，建议日PV值小的中小型企业web均可采用如下方案实行，下面直接上安装步骤：

一、环境：
centos5.3、nginx-0.7.51、keepalived-1.1.19
主nginx负载均衡器：192.168.0.154
辅nginx负载均衡器：192.168.9.155
vip：192.168.0.188

二、安装keepalived

#tar zxvf keepalived-1.1.19.tar.gz
#cd keepalived-1.1.19
#./configure --prefix=/usr/local/keepalived
#make
#make install
#cp /usr/local/keepalived/sbin/keepalived /usr/sbin/
#cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
#cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/
#mkdir /etc/keepalived
#cd /etc/keepalived/

vim keepalived.conf

! Configuration File for keepalived
global_defs {
    notification_email {
    yuhongchun027@163.com
         }
    notification_email_from keepalived@chtopnet.com
    smtp_server 127.0.0.1
    smtp_connect_timeout 30
    router_id LVS_DEVEL
}
vrrp_instance VI_1 {
     state MASTER
     interface eth0
     virtual_router_id 51
     mcast_src_ip 192.168.0.154    <==主nginx的IP地址
     priority 100
     advert_int 1
     authentication {
         auth_type PASS
         auth_pass chtopnet
     }
     virtual_ipaddress {
         192.168.0.188                      <==VIP地址
     }
}

#service keepalived start
我们来看一下日志：
[root@ltos ~]# tail /var/log/messages

Oct 6 03:25:03 ltos avahi-daemon[2306]: Registering new address record for 192.168.0.188 on eth0.
Oct 6 03:25:03 ltos avahi-daemon[2306]: Registering new address record for 192.168.0.154 on eth0.
Oct 6 03:25:03 ltos avahi-daemon[2306]: Registering HINFO record with values 'I686'/'LINUX'.
Oct 6 03:25:23 ltos avahi-daemon[2306]: Withdrawing address record for fe80::20c:29ff:feb9:eeab on eth0.
Oct 6 03:25:23 ltos avahi-daemon[2306]: Withdrawing address record for 192.168.0.154 on eth0.
Oct 6 03:25:23 ltos avahi-daemon[2306]: Host name conflict, retrying with <ltos-31>
Oct 6 03:25:23 ltos avahi-daemon[2306]: Registering new address record for fe80::20c:29ff:feb9:eeab on eth0.
Oct 6 03:25:23 ltos avahi-daemon[2306]: Registering new address record for 192.168.0.188 on eth0.
Oct 6 03:25:23 ltos avahi-daemon[2306]: Registering new address record for 192.168.0.154 on eth0.
Oct 6 03:25:23 ltos avahi-daemon[2306]: Registering HINFO record with values 'I686'/'LINUX'.

很显然vrrp已经启动，我们还可以通过命令：#ip a 来检查

[root@ltos html]# ip a

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue
     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
     inet 127.0.0.1/8 scope host lo
     inet6 ::1/128 scope host
        valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
     link/ether 00:0c:29:ba:9b:e7 brd ff:ff:ff:ff:ff:ff
     inet 192.168.0.154/24 brd 192.168.0.255 scope global eth0
     inet 192.168.0.188/32 scope global eth0
     inet6 fe80::20c:29ff:feba:9be7/64 scope link
        valid_lft forever preferred_lft forever
3: sit0: <NOARP> mtu 1480 qdisc noop
     link/sit 0.0.0.0 brd 0.0.0.0

说明vip已经启动，这样主服务器就配置好了，辅机的配置大致一样，除了配置文件有少部分的变化，下面贴出辅机的配置文件：

! Configuration File for keepalived
global_defs {
    notification_email {
    yuhongchun027@163.com
         }
    notification_email_from keepalived@chtopnet.com
    smtp_server 127.0.0.1
    smtp_connect_timeout 30
    router_id LVS_DEVEL
}
vrrp_instance VI_1 {
     state BACKUP
     interface eth0
     virtual_router_id 51
     mcast_src_ip 192.168.0.155             <==从nginx的IP的地址
     priority 100
     advert_int 1
     authentication {
         auth_type PASS
         auth_pass chtopnet
     }
     virtual_ipaddress {
         192.168.0.188
     }
}

检查其配置
[root@ltos html]# ip a

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue
     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
     inet 127.0.0.1/8 scope host lo
     inet6 ::1/128 scope host
        valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
     link/ether 00:0c:29:ba:9b:e7 brd ff:ff:ff:ff:ff:ff
     inet 192.168.0.155/24 brd 192.168.0.255 scope global eth0
     inet 192.168.0.188/32 scope global eth0
     inet6 fe80::20c:29ff:feba:9be7/64 scope link
        valid_lft forever preferred_lft forever
3: sit0: <NOARP> mtu 1480 qdisc noop
     link/sit 0.0.0.0 brd 0.0.0.0

测试其效果方法很简单，分别在主辅机上建立不同的主页，index.html的内容分别为192.168.0.154,192.168.0.155，然后用客户机上elinks http://192.168.0.188,主机down掉后辅机会马上接替提供服务，间隔时间几乎无法感觉出来,

Answer 1

还是做一个脚本来检测服务，可以去查询一下 keepalived 中执行脚本就可以解决楼上的问题

Answer 2

这么做我发现了一个问题 就是假如服务DOWN了 但网络正常通信 服务是不会飘过来的