通過ip地址漂移技術(keepalived)實現高可用和雙主節點負載均衡

Master：192.168.1.1 #提供負載均衡

Backup：192.168.1.2 #均衡備機

VIP：192.168.1.250 ：虛IP

原理：虛IP 是外網訪問的IP地址，通過 keepalived 設置，以及 VRRP 將 VIP 綁定到主機和備機上，通過權重實現控制。當主機宕掉後，keepalived 釋放對主機的控制，備機接管虛IP。

1.安裝Nginx

http://www.cnblogs.com/wazy/p/8108824.html

2.安裝Keepalived

wget http://www.keepalived.org/software/keepalived-1.2.7.tar.gz
tar -zxf keepalived-1.2.7.tar.gz
cd keepalived-1.2.7
./configure --prefix=/usr/local/keepalived --with-kernel-dir=/usr/src/kernels/3.10.0-514.el7.x86_64/

#可能會出現configure: error: Popt libraries is required
解決方法：
    yum -y install popt-devel
再次./configure

make && make install

設置成為服務並開機啟動:
cp /usr/local/keepalived/sbin/keepalived /usr/sbin/
cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/
cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
cp /usr/local/keepalived/etc/keepalived/   /etc
 
/etc/rc.d/init.d/keepalived status
chkconfig --add keepalived
chkconfig keepalived on

3.修改配置文件

　　1）Master

vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 51
    mcast_src_ip 192.168.1.1
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.1.250
    }
}

　　2）Backup

vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 51
    mcast_src_ip 192.168.1.2
    priority 99
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.1.250
    }
}

啟動keepalivd，然後查看Master的網卡，有兩個ip，一個本機ip一個VIP

這時候ping 192.168.1.250應該是通的
實際上這時候 108 是被綁到主機上的。在主機上：

查看系統日誌
#tailf /var/log/messages
Dec 26 15:30:59 localhost Keepalived_healthcheckers[38737]: Timeout connect, timeout server [192.168.201.100]:443.
Dec 26 15:30:59 localhost Keepalived_healthcheckers[38737]: Timeout connect, timeout server [192.168.200.2]:1358.
Dec 26 15:30:59 localhost Keepalived_healthcheckers[38737]: Timeout connect, timeout server [192.168.200.3]:1358.
Dec 26 15:30:59 localhost Keepalived_healthcheckers[38737]: Timeout connect, timeout server [192.168.200.4]:1358.
Dec 26 15:30:59 localhost Keepalived_healthcheckers[38737]: Timeout connect, timeout server [192.168.200.5]:1358.
Dec 26 15:31:05 localhost Keepalived_healthcheckers[38737]: Timeout connect, timeout server [192.168.201.100]:443.
Dec 26 15:31:05 localhost Keepalived_healthcheckers[38737]: Timeout connect, timeout server [192.168.200.2]:1358.
......
可以看到.VRRP(虛擬路由冗余協議)已經啟動.我們可以通過命令 ip addr 來檢查主 Nginx 上的 IP 分配情況.

#ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    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 state UP qlen 1000
    link/ether 00:0c:29:d4:83:a4 brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.1/24 brd 192.168.1.255 scope global eth0
    inet 192.168.1.250/32 scope global eth0
    inet6 fe80::20c:29ff:fed4:83a4/64 scope link 
       valid_lft forever preferred_lft forever

#tcpdump 抓包
tcpdump vrrp
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
22:16:37.890619 IP ACA832B0.ipt.aol.com > vrrp.mcast.net: VRRPv2, Advertisement, vrid 51, prio 100, authtype simple, intvl 1s, length 20
22:16:38.892503 IP ACA832B0.ipt.aol.com > vrrp.mcast.net: VRRPv2, Advertisement, vrid 51, prio 100, authtype simple, intvl 1s, length 20
22:16:39.900436 IP ACA832B0.ipt.aol.com > vrrp.mcast.net: VRRPv2, Advertisement, vrid 51, prio 100, authtype simple, intvl 1s, length 20
22:16:40.902613 IP ACA832B0.ipt.aol.com > vrrp.mcast.net: VRRPv2, Advertisement, vrid 51, prio 100, authtype simple, intvl 1s, length 20
22:16:41.905640 IP ACA832B0.ipt.aol.com > vrrp.mcast.net: VRRPv2, Advertisement, vrid 51, prio 100, authtype simple, intvl 1s, length 20
22:16:42.907636 IP ACA832B0.ipt.aol.com > vrrp.mcast.net: VRRPv2, Advertisement, vrid 51, prio 100, authtype simple, intvl 1s, length 20
...
到這裏我們已經完成了一個 nginx + keepalived

接下來我們可以完善一下，做一個主備切換

加上實時監控，如果發現負載均衡的 Nginx 出現問題，就將該機器上的 Keepalived 服務停掉。

vi /etc/rc.d/init.d/nginxcheck

#!/bin/bash
#描述：這是用於監控nginx服務的腳本
#chkconfig: - 57 75

while :
        do
                nginxpid=`ps -C nginx --no-header | wc -l`
                if [ $nginxpid -eq 0 ]; then
                        service keepalived stop
                        sleep 3
                        echo $nginxpid  >> /tmp/nginx_info
                elif [ $nginxpid -ne 0 ]; then
                        service keepalived start
                        sleep 3
                        echo $nginxpid >> /tmp/nginx_infoa
                fi
        done


chkconfig --add nginxcheck
chkconfig nginxcheck on

或者在/etc/rc.local 將腳本放進去

　　然後關閉nginx看看是否能訪問192.168.1.250,以及Backup的vip是否綁定

Nginx + Keepalived