一、Keepalived简介
Keepalived的作用是检测web服务器的状态,如果有一台web服务器死机,或工作出现故障,Keepalived将检测到,并将有故障的web服务器从系统中剔除,当web服务器工作正常后Keepalived自动将web服务器加入到服务器群中,这些工作全部自动完成,不需要人工干涉,需要人工做的只是修复故障的web服务器。
Layer3,4&7工作在IP/TCP协议栈的IP层,TCP层,及应用层,原理分别如下:
Layer3:Keepalived使用Layer3的方式工作式时,Keepalived会定期向服务器群中的服务器发送一个ICMP的数据包(既我们平时用的Ping程序),如果发现某台服务的IP地址没有激活,Keepalived便报告这台服务器失效,并将它从服务器群中剔除,这种情况的典型例子是某台服务器被非法关机。Layer3的方式是以服务器的IP地址是否有效作为服务器工作正常与否的标准。在本文中将采用这种方式。
Layer4:如果您理解了Layer3的方式,Layer4就容易了。Layer4主要以TCP端口的状态来决定服务器工作正常与否。如web server的服务端口一般是80,如果Keepalived检测到80端口没有启动,则Keepalived将把这台服务器从服务器群中剔除。
Layer7:Layer7就是工作在具体的应用层了,比Layer3,Layer4要复杂一点,在网络上占用的带宽也要大一些。Keepalived将根据用户的设定检查服务器程序的运行是否正常,如果与用户的设定不相符,则Keepalived将把服务器从服务器群中剔除。
二、安装配置
1.拓扑图
说明:1.两个代理服务器通过VIP向外提供数据
2.两个代理服务器都可以代理后端的服务器
3.为测试方便,后端服务器至提供静态页面
2.ip规划
功用 | ip地址 | 安装软件 |
VIP | 192.168.1.99 | |
反向代理1 | 192.168.1.201 | keepalived、haproxy |
反向代理2 | 192.168.1.204 | keepalived、haproxy |
web服务器1 | 192.168.1.202 | httpd |
web服务器2 | 192.168.1.203 | httpd |
3.安装配置haproxy
关于haproxy的详细配置,请参照http://wangfeng7399.blog.51cto.com/3518031/1405758
[[email protected] ~]# cat /etc/haproxy/haproxy.cfg #--------------------------------------------------------------------- # Example configuration for a possible web application. See the # full configuration options online. # # http://haproxy.1wt.eu/download/1.4/doc/configuration.txt # #--------------------------------------------------------------------- #--------------------------------------------------------------------- # Global settings #--------------------------------------------------------------------- global # to have these messages end up in /var/log/haproxy.log you will # need to: # # 1) configure syslog to accept network log events. This is done # by adding the ‘-r‘ option to the SYSLOGD_OPTIONS in # /etc/sysconfig/syslog # # 2) configure local2 events to go to the /var/log/haproxy.log # file. A line like the following can be added to # /etc/sysconfig/syslog # # local2.* /var/log/haproxy.log # log 127.0.0.1 local2 chroot /var/lib/haproxy pidfile /var/run/haproxy.pid maxconn 4000 user haproxy group haproxy daemon # turn on stats unix socket stats socket /var/lib/haproxy/stats #--------------------------------------------------------------------- # common defaults that all the ‘listen‘ and ‘backend‘ sections will # use if not designated in their block #--------------------------------------------------------------------- defaults mode http log global option httplog option dontlognull option http-server-close option forwardfor except 127.0.0.0/8 option redispatch retries 3 timeout http-request 10s timeout queue 1m timeout connect 10s timeout client 1m timeout server 1m timeout http-keep-alive 10s timeout check 10s maxconn 3000 #--------------------------------------------------------------------- # main frontend which proxys to the backends #--------------------------------------------------------------------- frontend main *:80 default_backend static #--------------------------------------------------------------------- # static backend for serving up images, stylesheets and such #--------------------------------------------------------------------- backend static balance roundrobin server node2 192.168.1.202:80 check maxconn 2000 server node3 192.168.1.203:80 check maxconn 2000 #--------------------------------------------------------------------- # round robin balancing between the various backends #---------------------------------------------------------------------
说明:两个节点的HAproxy的配置文件应该保持一样
4.测试haproxy的配置
5.安装配置keepalived
①、安装keepalived
keepalived的安装可以通过yum源来安装,也可以通过编译源码来安装,本处通过yum源赖安装
②、配置keepalived主节点
[[email protected] ~]# cat /etc/keepalived/keepalived.conf ! Configuration File for keepalived global_defs { //全局参数 notification_email { //邮件 [email protected] //收件人地址 } notification_email_from [email protected] //发件人地址 smtp_server 127.0.0.1 //邮件服务器的地址 smtp_connect_timeout 30 //间隔时间 router_id LVS_DEVEL //邮件服务器的组的id } vrrp_script chk_haproxy { script "killall -0 haproxy" //检查haproxy是否在线 interval 1 //检查间隔时间 weight -5 //如果检查失败,则权重-5 } vrrp_instance VI_1 { //定义第一个集群 state MASTER //初始状态为主节点,从节点应该为BACKUP interface eth0 //配置ip的端口 virtual_router_id 51 //本组集群的id号,主从节点必须一样 priority 100 //主节点的优先级,备用节点的优先级必须低于主节点 advert_int 1 //心跳检查间隔时间 authentication { auth_type PASS //通信为明文密码通信 auth_pass 1111 //通信的密码,主从节点必须一样 } virtual_ipaddress { 192.168.1.99 //定义一个VIP } track_script { //调用上面的命令 chk_haproxy } }
③、配置keepalived从节点
[[email protected] ~]# cat /etc/keepalived/keepalived.conf ! Configuration File for keepalived global_defs { notification_email { [email protected] } notification_email_from [email protected] smtp_server 127.0.0.1 smtp_connect_timeout 30 router_id LVS_DEVEL } vrrp_script chk_haproxy { script "killall -0 haproxy" interval 1 weight -5 } vrrp_instance VI_1 { state BACKUP interface eth0 virtual_router_id 51 priority 99 advert_int 1 authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 192.168.1.99 } track_script { chk_haproxy } }
6.测试
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 00:0c:29:56:78:cd brd ff:ff:ff:ff:ff:ff inet 192.168.1.204/24 brd 192.168.1.255 scope global eth0 inet 192.168.1.99/32 scope global eth0 inet6 fe80::20c:29ff:fe56:78cd/64 scope link tentative dadfailed valid_lft forever preferred_lft forever
可以看到ip地址已经配置上去了
我们可以看到网页访问正常
下面,我们模拟服务器损坏,将node1上的haproxy关掉,看看ip地址是否会转移到node4上
[[email protected] ~]# ip add 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 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:29:56:78:cd brd ff:ff:ff:ff:ff:ff inet 192.168.1.204/24 brd 192.168.1.255 scope global eth0 inet 192.168.1.99/32 scope global eth0 inet6 fe80::20c:29ff:fe56:78cd/64 scope link tentative dadfailed valid_lft forever preferred_lft forever
查看网页是否能够访问正常
OK!!可以看到我们的页面访问正常,这就可以实现当前段的一个反向代理服务器宕机或者后端的一个web服务宕机,服务都可以正常对外提供
7.扩展
我们还可以自定义通知机制
#!/bin/bash # Author: wangfeng7399<[email protected]> # description: An example of notify script # vip=192.168.1.99 contact=‘[email protected]‘ notify() { mailsubject="`hostname` to be $1: $vip floating" mailbody="`date ‘+%F %H:%M:%S‘`: vrrp transition, `hostname` changed to be $1" echo $mailbody | mail -s "$mailsubject" $contact } case "$1" in master) notify master exit 0 ;; backup) notify backup exit 0 ;; fault) notify fault exit 0 ;; *) echo ‘Usage: `basename $0` {master|backup|fault}‘ exit 1 ;; esac
在keepalived的配置文件中通过notify来调用,如下所示
notify_master "/etc/keepalived/notify.sh master" notify_backup "/etc/keepalived/notify.sh backup" notify_fault "/etc/keepalived/notify.sh fault"
大功告成,由于本人水平有限,可能有逻辑上的错误,请各位大神匹配指正
基于keepalived对HAproxy做高可用集群,布布扣,bubuko.com