系统环境:CentOS 5.5
开源软件:nginx-1.2.1.tar.gz ; keepalived-1.2.2.tar.gz
主服务器IP:211.151.138.2 从服务IP:211.151.138.3 虚IP:211.151.138.5 你可以将你网站域名解析到 211.151.138.5 这一个公网IP上,这样主从服务器可以轮流接管该虚IP,保证网站正常对外提供访问
keepalived 安装需要依赖 openssl , 直接yum安装即可,yum install openssl openssl-devel
nginx 的安装这里就不介绍了,网上相关文档很多,这里着重介绍 keepalived + nginx 的实现方式
一: 安装 keepalived
主从服务器都操作:
下载 keepalived 软件包
wget http://www.keepalived.org/software/keepalived-1.2.2.tar.gz
tar zxvf keepalived-1.2.2 .tar.gz
./configure
make && make install
默认情况下,keepalived 会安装在 /usr/local/keepalived 下,你可以通过 --prefix 定向其安装位置
cp /usr/local/keepalived/etc/rc.d/init.d/ /etc/init.d/
mkdir /etc/keepalived (默认情况下,keepalived 会读取 /etc/keepalived 下keepalived.conf 文件,如果你没有建立这个文件,keepalived也不会报错,但是你会发现,你所创建的关于keepalived的相关参数根本就没有体现,keepalived这一点做的让人挺迷惑的 )
二:此时,我们创建 keepalived.conf 文件
主服务器配置:
vim /etc/keepalived/keepalived.conf , 键入以下内容
global_defs {
notification_email {
[email protected] (这里可以定义多个报警邮箱)
}
notification_email_from [email protected] (报警人)
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_script chk_http_port {
script "/opt/tools/bin/check_ng.sh"
interval 2 (检测的间隔)
weight 2
}
vrrp_instance VI_1 {
state MASTER (显示定义为主服务器)
interface eth1 (绑定的网口,该网口即上面提到的两个IP的接口)
virtual_router_id 51 (定义的ID,官方的是 51,主从服务器必须一直)
mcast_src_ip 211.151.138.2 (主服务器的IP)
priority 100 (优先级,任意定义,但是一定要比从服务器高)
advert_int 1
authentication {
auth_type PASS
auth_pass 1111 (默认即可)
}
track_script {
chk_http_port (调用检测脚本)
}
virtual_ipaddress {
211.151.137.5 (绑定的虚IP)
}
}
从服务器配置
vim /etc/keepalived/keepalived.conf , 键入以下内容
global_defs {
notification_email {
[email protected] (这里可以定义多个报警邮箱)
}
notification_email_from [email protected] (报警人)
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_script chk_http_port {
script "/opt/tools/bin/check_ng.sh"
interval 2 (检测脚本执行的间隔)
weight 2
}
vrrp_instance VI_1 {
state BACKUP (显示定义为从服务器)
interface eth1 (绑定的网口,该网口即上面提到的两个IP的接口)
virtual_router_id 51 (定义的ID,官方的是 51,主从服务器必须一直)
mcast_src_ip 211.151.138.3 (从服务器的IP)
priority 50 (优先级,任意定义,但是一定要比主服务器低)
advert_int 1
authentication {
auth_type PASS
auth_pass 1111 (默认即可)
}
track_script {
chk_http_port (调用检测脚本)
}
virtual_ipaddress {
211.151.137.5 (绑定的虚IP)
}
}
我们编辑 vim /opt/tools/bin/check_ng.sh
#!/bin/bash
N= `ps -C nginx --no-header |wc -l`
if [ $N -eq 0 ];then
/usr/local/nginx/sbin/nginx
sleep 3
if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then
killall keepalived
fi
fi
这是一个针对nginx状态进行检测的脚本,第一次nginx服务死掉时,会重新启动,如果Nginx服务依旧没有起来,则杀掉keepalived进程
三:服务器上都启动 keepalived 进程
/etc/init.d/keepalived start
执行 /sbin/ip a 我们看一下IP的使用情况
主服务器:
eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
link/ether 80:c1:6e:71:f1:a2 brd ff:ff:ff:ff:ff:ff
inet 211.151.138.2/27 brd 211.151.138.31 scope global eth1
inet 211.151.138.5/32 scope global eth1
可见虚IP已经挂载上了
同时查看 tail -f /var/log/message , keepalived 日志显示如下:
Jun 28 18:44:25 proxy1 Keepalived_vrrp: Using LinkWatch kernel netlink reflector...
Jun 28 18:44:25 proxy1 Keepalived_vrrp: VRRP sockpool: [ifindex(3), proto(112), fd(10,11)]
Jun 28 18:44:25 proxy1 Keepalived_vrrp: VRRP_Script(chk_http_port) succeeded
Jun 28 18:44:26 proxy1 Keepalived_vrrp: VRRP_Instance(VI_1) Transition to MASTER STATE
Jun 28 18:44:27 proxy1 Keepalived_vrrp: VRRP_Instance(VI_1) Entering MASTER STATE (这里显示其角色为主服务)
Jun 28 18:44:27 proxy1 Keepalived_vrrp: VRRP_Instance(VI_1) setting protocol VIPs.
Jun 28 18:44:27 proxy1 Keepalived_vrrp: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth1 for 211.151.137.5
同时从服务器日志显示为:
Jun 28 18:42:14 proxy2 Keepalived: Starting Keepalived v1.2.2 (06/21,2012)
Jun 28 18:42:14 proxy2 Keepalived: Starting VRRP child process, pid=23588
Jun 28 18:42:14 proxy2 Keepalived_vrrp: Registering Kernel netlink reflector
Jun 28 18:42:14 proxy2 Keepalived_vrrp: Registering Kernel netlink command channel
Jun 28 18:42:14 proxy2 Keepalived_vrrp: Registering gratutious ARP shared channel
Jun 28 18:42:14 proxy2 Keepalived_vrrp: Opening file '/etc/keepalived/keepalived.conf'.
Jun 28 18:42:14 proxy2 Keepalived_vrrp: Configuration is using : 65440 Bytes
Jun 28 18:42:14 proxy2 Keepalived_vrrp: Using LinkWatch kernel netlink reflector...
Jun 28 18:42:14 proxy2 Keepalived_vrrp: VRRP_Instance(VI_1) Entering BACKUP STATE (显示为BACKUP,从)
Jun 28 18:42:14 proxy2 Keepalived_vrrp: VRRP sockpool: [ifindex(3), proto(112), fd(10,11)]
此时我们关闭主上的keepalived服务,则从的日志变为:
Jun 28 18:43:49 proxy2 Keepalived_vrrp: VRRP_Instance(VI_1) Transition to MASTER STATE
Jun 28 18:43:50 proxy2 Keepalived_vrrp: VRRP_Instance(VI_1) Entering MASTER STATE
Jun 28 18:43:50 proxy2 Keepalived_vrrp: VRRP_Instance(VI_1) setting protocol VIPs.
Jun 28 18:43:50 proxy2 Keepalived_vrrp: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth1 for 211.151.138.5
可见他已经接管了211.151.138.5 这一个虚IP,并且把自己的状态置为了主 MASTER
此时再把原来主上的keepalived进程起来,则其日志为:
Jun 28 18:44:26 proxy2 Keepalived_vrrp: VRRP_Instance(VI_1) Received higher prio advert
Jun 28 18:44:26 proxy2 Keepalived_vrrp: VRRP_Instance(VI_1) Entering BACKUP STATE
Jun 28 18:44:26 proxy2 Keepalived_vrrp: VRRP_Instance(VI_1) removing protocol VIPs.
Jun 28 18:44:26 proxy2 avahi-daemon[6552]: Withdrawing address record for 211.151.138.5 on eth1
表示接收到了更高权限的消息,于是他把自己的状态置为了从,并且归还 211.151.138.5 这个IP
如此,就实现了高可用 HA