Nginx+keepalived负载均衡高可用篇第③版

对付中、小型企业，假如没有资金去购买昂贵的四/七层负载均衡交换机，那么Nginx是不错的七层负载均衡选择，并且可以通过Nginx + Keepalived实现Nginx 负载均衡器双机互备，恣意一台呆板发生妨碍，对方都可以或许将假造IP吸取已往。以下内容为第三次更新了，下面将其安装步调具体阐发下：


一、拓扑环境：
二、安装keepalived
wget
tar zxvf keepalived-1.1.15.tar.gz
cd keepalived-1.1.15
./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 {

}
notification_email_from
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所在
 priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass chtopnet
}
virtual_ipaddress {
192.168.0.188 <==vip所在
 }
}
#service keepalived start
我们来看一下日记：
[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
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，我们还可以通过下令来反省
[root@ltos html]# ip a
1: lo: 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: 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: mtu 1480 qdisc noop
link/sit 0.0.0.0 brd 0.0.0.0

阐发vip已经启动，如许主理事器就设置好了，辅机的设置大抵一样，除了设置文件有少部分的变动，下
面贴出辅机的设置文件：
! Configuration File for keepalived
global_defs {
notification_email {

}
notification_email_from
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 <==辅nginx的IP的所在
 priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass chtopnet
}
virtual_ipaddress {
192.168.0.188 <==vip所在
}
}

反省其设置
[root@ltos html]# ip a
1: lo: 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: 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: mtu 1480 qdisc noop
link/sit 0.0.0.0 brd 0.0.0.0

测试其效果行动很大略，判别在主辅机上/var/www/html/下成立差别的主页及内容文件index.html，内容判别为192.168.0.154,192.168.0.155，然后用客户机上elinks ,主机down掉后辅机会立刻接替供给做事，隔断工夫险些无法感伤出来；但假如是停掉master的nginx做事，keepalived就不能主动启动nginx做事了，这个也是相对付heartbeat2.X不完美的地方，即它不能做到做事级别-Nginx的HA。


※这里要阐发的是：一、怎样让master状况的主机挂掉后不抢占的办法：可将二台Nginx负载均衡器均设成backup状况是由于nopreempt(不抢占)只支持backup模式，而让哪一台backup成为master，这个由优先级priority为决议，这个设置是参考了《Keepalived权势巨子指南》做法，二、此种架构的错误是备机做事器处于闲置状况，浪费了硬件资源，假如要有效的操作二台nginx负载均衡器，可参考张宴的金山悠闲网nginx负载均衡的双机热备的做法；三、keepalived比拟heartbeat2.X而言，它如今不能做nginx做事的HA，但由于如今nginx作反向署理/负载均衡器非常稳定，出现宕机的机率微乎其乎(关键是nginx的master进程超稳定)，我做的一些基于nginx负载均衡的小项目已在线稳定一年以上(险些从来没出现单nginx负载均衡挂掉的情况)，以是这个可以操纵于成熟的生产环境(譬喻新浪)；在生产环境下，比起用shell脚本监控nginx的master状况，反而效果不如采用nagios/手机短信报警的行动更为高效。

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