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keepalived个人简单理解来说就是实现一个虚IP在keepalived主从服务器之间切换的功能，当主的keeplived挂掉，从机会无缝接管该虚IP。 keepalived一般都会配合某个具体服务工作，例如mysql,drbd，haproxy等，这篇博客介绍的就是haproxy,前期做好keepalived配置后，做一个切换脚本，当haproxy挂掉后，脚本会执行keepalived关闭操作，从而让从机接管,其实该虚IP其实会和本机的物理IP做绑定，访问虚IP其实就可以理解为访问本机物理IP，该虚IP会在触发脚本后切换到从机，访问该虚IP其实就是在访问从机物理IP，实现haproxy的高可用性。
系统环境：centos6.3 apache: httpd-2.4.4 haproxy: haproxy-1.4.8 keepalived：keepalived-1.2.7
haproxy VIP: 192.168.7.70 haproxy1: 192.168.7.71 ha1.example.com haproxy2: 192.168.7.72 ha2.example.com apache1: 192.168.7.73 www1.example.com apache2: 192.168.7.74 www2.example.com
(haproxy1)为仅haproxy1配置 (haproxy2)为仅haproxy2配置 (haproxy1，haproxy2)为haproxy1和haproxy2都得配置
关闭iptables和SELINUX # service iptables stop # setenforce 0 # vi /etc/sysconfig/selinux --------------- SELINUX=disabled ---------------
apache安装（略） 安装完毕只需配置访问根页面显示本机IP地址
一.haproxy安装配置：(haproxy1，haproxy2) # wget http://haproxy.1wt.eu/download/1.4/src/haproxy-1.4.8.tar.gz # tar zxvf haproxy-1.4.8.tar.gz # cd haproxy-1.4.8 # uname -a //查看linux内核版本 # make TARGET=linux26 PREFIX=/usr/local/haproxy # make install PREFIX=/usr/local/haproxy # useradd -s /sbin/nologin haproxy # passwd haproxy # chown -R haproxy.haproxy /usr/local/haproxy
配置： # vi /usr/local/haproxy/haproxy.cfg ----------------- global log 127.0.0.1local0 maxconn 5120 chroot /usr/local/haproxy user haproxy group haproxy daemon quiet nbproc 1 pidfile /usr/local/haproxy/haproxy.pid #启动服务后后会滚动日志，生产环境建议注释掉 debug defaults log 127.0.0.1local3 modehttp optionhttplog optionhttpclose option dontlognull #option forwardfor option redispatch retries2 maxconn 2000 balance source contimeout 5000 clitimeout 50000 srvtimeout 50000
listen web_proxy :80 server www1 192.168.7.73:80 weight 5 check inter 2000 rise 2 fall 5
server www2 192.168.7.74:80 weight 5 check inter 2000 rise 2 fall 5
listen stats :8888 mode http #transparent stats uri / haproxy-stats stats realm Haproxy \ statistic #认证 stats auth haproxy:password -----------------
启动haproxy # /usr/local/haproxy/sbin/haproxy -f /usr/local/haproxy/haproxy.cfg & 注：这里加上“&”是为了让haproxy服务后台运行，去掉“&”可实时查看其滚动日志 日志： ------------------------ Available polling systems : sepoll : pref=400, test result OK epoll : pref=300, test result OK poll : pref=200, test result OK select : pref=150, test result OK Total: 4 (4 usable), will use sepoll. Using sepoll() as the polling mechanism. 00000000:web_proxy.accept(0004)=0007 from [192.168.7.129:5752] 00000000:web_proxy.clireq[0007:ffff]: GET / HTTP/1.1 00000000:web_proxy.clihdr[0007:ffff]: Accept: text/html, application/xhtml+xml, */* 00000000:web_proxy.clihdr[0007:ffff]: Accept-Language: zh-CN 00000000:web_proxy.clihdr[0007:ffff]: User-Agent: Mozilla/5.0 (compatible; MSIE
9.0; Windows NT 6.1; WOW64; Trident/5.0) 00000000:web_proxy.clihdr[0007:ffff]: Accept-Encoding: gzip, deflate 00000000:web_proxy.clihdr[0007:ffff]: Host: 192.168.7.71 00000000:web_proxy.clihdr[0007:ffff]: If-Modified-Since: Tue, 28 May 2013 18:22:10
GMT 00000000:web_proxy.clihdr[0007:ffff]: If-None-Match: "10-4ddcb57ecf1ee" 00000000:web_proxy.clihdr[0007:ffff]: Connection: Keep-Alive 00000000:web_proxy.srvrep[0007:0008]: HTTP/1.1 304 Not Modified 00000000:web_proxy.srvhdr[0007:0008]: Date: Tue, 28 May 2013 19:48:35 GMT 00000000:web_proxy.srvhdr[0007:0008]: Server: Apache/2.4.4 (Unix) 00000000:web_proxy.srvhdr[0007:0008]: Connection: close 00000000:web_proxy.srvhdr[0007:0008]: ETag: "10-4ddcb57ecf1ee" 00000000:web_proxy.srvcls[0007:0008] 00000000:web_proxy.clicls[0007:0008] 00000000:web_proxy.closed[0007:0008] ------------------------
查看是否启动 # ps -ef|grep haproxy -------------------------- # ps -ef |grep haproxy haproxy 2255 1 0 03:33 ? 00:00:00 /usr/local/haproxy/sbin/haproxy -f /usr/local/haproxy/haproxy.cfg root 2323 2291 0 03:56 pts/1 00:00:00 grep haproxy --------------------------
重启haproxy # pkill haproxy # /usr/local/haproxy/sbin/haproxy -f /usr/local/haproxy/haproxy.cfg
其中： haproxy代理：192.168.7.71:80 apache1： 192.168.7.73:80 apache2： 192.168.7.74:80 统计页面监听的端口：8888 访问页面： http://192.168.7.71:8888/haproxy-stats 认证账号/密码：haproxy/password
总结： 通过日志可以看出，客户端192.168.7.129连接haproxy192.168.7.71的80端口，且客户端无论如何刷新页面，haproxy都只会把访问请求跳转到apache2的192.168.7.74地址，这是因为balance source这个参数会保持会话ID,如果改成balance roundrobin模式，那么客户端会轮流连接两台web服务器，线上还是建议使用balance source,这样会保持某一客户端在长时间内保持他的会话，不会来回跳转。 这里其实已经利用haproxy完成了对两台apache服务器的负载均衡功能，但如何保证负载均衡的高可用性，这里就得利用keepalived的热备功能，保证haproxy1如果挂掉，haproxy2能实时接管，实现网站前端负载均衡高可用，这也是我们目前比较流行的组合haproxy+keepalived。
二.keepalived安装配置：(haproxy1，haproxy2）
# wget http://www.keepalived.org/software/keepalived-1.2.7.tar.gz # tar zxvf keepalived-1.2.7.tar.gz # cd keepalived-1.2.7 # ./configure --prefix=/usr/local/keepalived --with-kernel- dir=/usr/src/kernels/2.6.32-279.el6.x86_64 # make && make install
设置keepalived启动脚本 # cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/ # cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/ # mkdir /etc/keepalived # cp /usr/local/keepalived/sbin/keepalived /usr/sbin/ # chkconfig keepalived on
(haproxy1）
# vi /etc/keepalived/keepalived.conf ---------------------- ! Configuration File for keepalived
global_defs { router_id LVS_DEVEL } vrrp_instance VI_1 { state MASTER interface eth0 virtual_router_id 51 priority 150 advert_int 1 authentication { auth_type PASS auth_pass 1111 }
virtual_ipaddress { 192.168.7.70 } } ----------------------
(haproxy2）
# vi /etc/keepalived/keepalived.conf ---------------------- ! Configuration File for keepalived
global_defs { router_id LVS_DEVEL } vrrp_instance VI_1 { state BACKUP interface eth0 virtual_router_id 51 priority 120 advert_int 1 authentication { auth_type PASS auth_pass 1111 }
virtual_ipaddress { 192.168.7.70 } } ----------------------
启动keepalived # service keepalived start # ps -ef |grep keepalived ---------------------- root 1726 1722 0 10:57 ? 00:00:00 sh /etc/keepalived/check_haproxy.sh root 2678 1 0 11:15 ? 00:00:00 keepalived -D root 2680 2678 0 11:15 ? 00:00:00 keepalived -D root 2681 2678 0 11:15 ? 00:00:00 keepalived -D root 2691 2178 0 11:15 pts/1 00:00:00 grep keepalived -----------------------
创建haproxy+keepalived脚本： 实现当haproxy挂掉后，能再次启动haproxy,若无法再次启动则彻底关闭keepalived将VIP交给 从机处理。 (haproxy1，haproxy2） # vi /etc/keepalived/check_haproxy.sh --------------------- #!/bin/bash while : do hapid=`ps -C haproxy --no-header |wc -l` if [ $hapid -eq 0 ];then /usr/local/haproxy/sbin/haproxy -f /usr/local/haproxy/haproxy.cfg sleep 5 if [ $hapid -eq 0 ];then /etc/init.d/keepalived stop fi fi sleep 5 done -------------------- # chmod 755 /etc/keepalived/check_haproxy.sh # nohup sh /etc/keepalived/check_haproxy.sh
注；该脚本参考酒哥的"构建高可用LINUX服务器"一书，需在keepalived开机正常启动后，方可在主从机执行。 本人实测，不能将该脚本做开机启动，会导致开机将keepalived服务关闭，如想实现开机自动执行该脚本，估计要做脚本语句优化，这里有兴趣的朋友可以帮忙修改一下。
三.测试： 1.在两台机器上分别执行ip add，目前显示VIP在haproxy1上与本机网卡绑定 (haproxy1） # ip add ----------------------- eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 00:0c:29:d2:c6:75 brd ff:ff:ff:ff:ff:ff inet 192.168.7.71/24 brd 192.168.7.255 scope global eth0 inet 192.168.7.70/32 scope global eth0 inet6 fe80::20c:29ff:fed2:c675/64 scope link valid_lft forever preferred_lft forever ----------------------- (haproxy2） # ip add ----------------------- eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 00:0c:29:ff:21:19 brd ff:ff:ff:ff:ff:ff inet 192.168.7.72/24 brd 192.168.7.255 scope global eth0 inet6 fe80::20c:29ff:feff:2119/64 scope link valid_lft forever preferred_lft forever ----------------------- 在浏览器访问该虚IP: http://192.168.7.70 返回如图：
证明，keepalived让haproxy1接管负载均衡，将页面跳转到apache2上
2.停掉haproxy1上的haproxy服务，5秒后keepalived会自动将其再次启动 （haproxy1） # pkill haproxy 等5秒 # ps -ef |grep haproxy -------------- ps -ef |grep haproxy root 1712 1708 0 01:17 ? 00:00:00 sh /etc/keepalived/check_haproxy.sh haproxy 2440 1 0 01:29 ? 00:00:00 /usr/local/haproxy/sbin/haproxy -f /usr/local/haproxy/haproxy.cfg root 2443 1807 0 01:29 pts/1 00:00:00 grep haproxy --------------
3.停掉主的keepalived，备机马上接管服务 （haproxy1） # service keepalived stop # uname -a --------------- Linux ha1.example.com 2.6.32-279.el6.x86_64 #1 SMP Fri Jun 22 12:19:21 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux --------------- （haproxy2） # ip add eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 00:0c:29:ff:21:19 brd ff:ff:ff:ff:ff:ff inet 192.168.7.72/24 brd 192.168.7.255 scope global eth0 inet 192.168.7.70/32 scope global eth0 inet6 fe80::20c:29ff:feff:2119/64 scope link valid_lft forever preferred_lft forever # uname -a --------------- Linux ha2.example.com 2.6.32-279.el6.x86_64 #1 SMP Fri Jun 22 12:19:21 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux --------------- 现已跳转到haproxy2,在浏览器再次访问该虚IP: http://192.168.7.70 返回如图：
---------大功告成---------
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