Nginx+keepalived負載均衡篇
由於nginx的url hash功能可以很好的提升squid的性能，所以我把squid前端的負載均衡器更換為nginx，但是一台nginx就形成了單點，現在使用keepalived來解決這個問題，keepalived的故障轉移時間很短，而且配置簡單，這也是選擇keepalived的一個主要原因，建議日PV值小的中小型企業web均可採用如下方案實行，下面直接上安裝步驟：
一、環境：
centos5.3、nginx-0.7.51、keepalived-1.1.19
主nginx負載均衡器：192.168.0.154
輔nginx負載均衡器：192.168.9.155
vip：192.168.0.188
二、安裝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
我們來看一下日誌：
# tail /var/log/messages
Oct 6 03:25:03 ltos avahi-daemon: Registering new address record for 192.168.0.188 on eth0.
Oct 6 03:25:03 ltos avahi-daemon: Registering new address record for 192.168.0.154 on eth0.
Oct 6 03:25:03 ltos avahi-daemon: Registering HINFO record with values 'I686'/'LINUX'.
Oct 6 03:25:23 ltos avahi-daemon: Withdrawing address record for fe80::20c:29ff:feb9:eeab on eth0.
Oct 6 03:25:23 ltos avahi-daemon: Withdrawing address record for 192.168.0.154 on eth0.
Oct 6 03:25:23 ltos avahi-daemon: Host name conflict, retrying with
Oct 6 03:25:23 ltos avahi-daemon: Registering new address record for fe80::20c:29ff:feb9:eeab on eth0.
Oct 6 03:25:23 ltos avahi-daemon: Registering new address record for 192.168.0.188 on eth0.
Oct 6 03:25:23 ltos avahi-daemon: Registering new address record for 192.168.0.154 on eth0.
Oct 6 03:25:23 ltos avahi-daemon: Registering HINFO record with values 'I686'/'LINUX'.
很顯然vrrp已經啟動，我們還可以通過命令：#ip a 來檢查
# 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
說明vip已經啟動，這樣主伺服器就配置好了，輔機的配置大致一樣，除了配置文件有少部分的變化，下面貼出輔機的配置文件：
! 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 <==從nginx的IP的地址
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass chtopnet
}
virtual_ipaddress {
192.168.0.188
}
}
檢查其配置
# 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
測試其效果方法很簡單，分別在主輔機上建立不同的主頁，index.html的內容分別為192.168.0.154,192.168.0.155，然後用客戶機上elinks http://192.168.0.188,主機down掉后輔機會馬上接替提供服務，間隔時間幾乎無法感覺出來, 《解決方案》
這麼做我發現了一個問題 就是假如服務DOWN了 但網路正常通信 服務是不會飄過來的 《解決方案》
還是做一個腳本來檢測服務，可以去查詢一下 keepalived 中執行腳本就可以解決樓上的問題
