keepalive
简述
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。
- 详细参考 http://www.oschina.net/p/keepalived
配置实例
VIP: 192.168.199.177
RealServer1： 192.168.199.222
RealServer2： 192.168.199.193
MASTER 配置
! Configuration File for keepalived
vrrp_instance VI_1 {
state MASTER
interface eth2
garp_master_delay 10
smtp_alert
virtual_router_id 51
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.199.177
}
}
virtual_server i192.168.199.177 80 {
delay_loop 6
lb_algo rr
lb_kind DR
persistence_timeout 50
protocol TCP
real_server 192.168.199.222 80 {
weight 3
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
real_server 192.168.199.193 80 {
weight 3
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}
BACKUP
! Configuration File for keepalived
vrrp_instance VI_1 {
state BACKUP
interface eth2
garp_master_delay 10
smtp_alert
virtual_router_id 51
priority 50
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.199.177
}
}
virtual_server i192.168.199.177 80 {
delay_loop 6
lb_algo rr
lb_kind DR
persistence_timeout 50
protocol TCP
real_server 192.168.199.222 80 {
weight 3
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
real_server 192.168.199.193 80 {
weight 3
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}
192.168.199.193: service keepalived restart
192.168.199.222: service keepalived restart
配置完成
! Configuration File for keepalived
global_defs {
notification_email { 定义接受邮件的邮箱
[email protected]
[email protected]
[email protected]
}
notification_email_from [email protected] 定义发送邮件的邮箱
smtp_server 192.168.200.1
smtp_connect_timeout 30
router_id LVS_MASTER lvs服务器标识符
}
vrrp_instance LVSMASTER { lvs实例标识
state MASTER 服务器状态
interface eth0 监控的端口
virtual_router_id 51 虚拟路由标识，一组lvs的虚拟路由标识必须相同，这样才能切换
priority 100 lvs服务启动优先级，值越大，优先级越高，BACKUP 不能大于MASTER
advert_int 2 lvs服务器之间的存活检查时间2s
authentication {
auth_type PASS 认证类型
auth_pass hylanda 认证密码，一组lvs 服务器的认证密码必须一致
}
virtual_ipaddress {
192.168.0.138 虚拟ip或服务ip
}
}
virtual_server 192.168.0.138 80 { 虚拟服务运行方式定义
delay_loop 5 检查realserver存活的间隔时间
lb_algo rr 负载均衡算法
lb_kind DR 请求转发方式
persistence_timeout 50 连接保持时间
protocol TCP
real_server 192.168.0.132 80 { 真实服务器定义
weight 1 负载参数
TCP_CKECK {
connect_timeout 10 连接超时时间
nb_get_retry 3 重试连接的次数
delay_before_reitry 3 每次连接间隔
connect_port 80 端口
}
}
real_server 192.168.0.133 80 {
weight 1
TCP_CHECK {
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}
3.配置keepalive
两台服务器端keepalived.conf内容都为如下，都设置为backup，不抢占，注意修改优先级不同,更详细的keepalived配置文件说明可以执行man keepalived.conf查看：
! 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
}
监控服务.NGINX mysql等
vrrp_script chk_nginx {
script "/home/check_nginx.sh"
interval 2
weight 2
}
vrrp_instance VI_1 {
state BACKUP #主从设置 MASTER
interface eth2 #网卡名
virtual_router_id 51
mcast_src_ip 10.0.1.133 #本机IP
priority 50 #从机小于主机
advert_int 1
authentication {
auth_type PASS
auth_pass chtopnet
}
virtual_ipaddress {
10.0.1.2 #VIP 的IP
}
track_script {
chk_nginx #检测脚本
}
}
virtual_server 10.0.1.2 80 {
delay_loop 6
lb_algo rr
lb_kind DR
persistence_timeout 50
protocol TCP
real_server 10.0.1.132 80 {
weight 3
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
real_server 10.0.1.133 80 {
weight 3
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}
启动相关服务。我在这儿使用的是nginx ，每个上面开了一个站点，通过IP可以直接访问的。启动keepalive后，就可以通过VIP的虚拟IP 10.0.1.2来访问站点了，测试方法就是 停止任何其中一个站点，看它是否能自动切换到从服务器上。
上面代码中 nginx的检测脚本如下 ：
!/bin/bash
if [ “$(ps -ef | grep “nginx: master process”| grep -v grep )” == “” ]
then
/usr/local/nginx/sbin/nginx
sleep 5
if [ “$(ps -ef | grep “nginx: master process”| grep -v grep )” == “” ]
then
killall keepalived
fi
fi
在两台Web Server上执行realserver.sh脚本，为lo:0绑定VIP地址10.0.1.2、抑制ARP广播。
!/bin/bash
description: Config realserver
VIP=10.0.1.2
/etc/rc.d/init.d/functions
case “$1” in
start)
/sbin/ifconfig lo:0 $VIP netmask 255.255.255.255 broadcast $VIP
/sbin/route add -host $VIP dev lo:0
echo "1" >/proc/sys/net/ipv4/conf/lo/arp_ignore
echo "2" >/proc/sys/net/ipv4/conf/lo/arp_announce
echo "1" >/proc/sys/net/ipv4/conf/all/arp_ignore
echo "2" >/proc/sys/net/ipv4/conf/all/arp_announce
sysctl -p >/dev/null 2>&1
echo "RealServer Start OK"
;;
stop)
/sbin/ifconfig lo:0 down
/sbin/route del $VIP >/dev/null 2>&1
echo "0" >/proc/sys/net/ipv4/conf/lo/arp_ignore
echo "0" >/proc/sys/net/ipv4/conf/lo/arp_announce
echo "0" >/proc/sys/net/ipv4/conf/all/arp_ignore
echo "0" >/proc/sys/net/ipv4/conf/all/arp_announce
echo "RealServer Stoped"
;;
*)
echo "Usage: $0 {start|stop}"
exit 1
esac
exit 0
分别在主从机上执行 sh realserver.sh start 就可实现负载均衡及高可用集群了