Keepalived高可用LVS

LVS只是做一个负载均衡，通过访问VIP来访问后端的网站程序，一旦LVS宕机，整个网站就访问不了，这就出现了单点。所以要结合keepalive这种高可用软件来保证整个网站的高可用。本文将介绍如何利用keepalive来实现LVS的高可用(以LVS的DR模式为例，生产环境后台的real server 网站内容是一致的，为了看到实验效果，这里是两个不同的页面)。

实验拓扑：

1.在两台Real Server上配置web服务

2.配置两台Real Server

配置脚本如下：
#!/bin/bash
#

VIP='10.1.88.88'
NETMASK='255.255.255.255'
IFACE='lo:0'

case $1 in
start)
echo 1 > /proc/sys/net/ipv4/conf/all/arp_ignore
echo 1 > /proc/sys/net/ipv4/conf/lo/arp_ignore
echo 2 > /proc/sys/net/ipv4/conf/all/arp_announce
echo 2 > /proc/sys/net/ipv4/conf/lo/arp_announce

ifconfig $IFACE $VIP broadcast $VIP netmask $NETMASK up
route add -host $VIP $IFACE
;;
stop)
echo 0 > /proc/sys/net/ipv4/conf/all/arp_ignore
echo 0 > /proc/sys/net/ipv4/conf/lo/arp_ignore
echo 0 > /proc/sys/net/ipv4/conf/all/arp_announce
echo 0 > /proc/sys/net/ipv4/conf/lo/arp_announce

ifconfig $IFACE down
;;
*)
echo "Usage: $(basename $0) {start|stop}"
exit 1
esac

3.配置keepalived
keepalived master的配置：
! Configuration File for keepalived

global_defs {
notification_email {
root@localhost
}
notification_email_from keepalived@localhost
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id node1
}

vrrp_script chk_down { #配置脚本
script "[[ -f /etc/keepalived/down ]] && exit 1 || exit 0" #脚本内容
interval 2 #间隔两秒执行一次脚本
weight -6 #如果脚本执行失败则优先级减6
}

vrrp_instance VI_1 { #配置实例
state MASTER #状态
interface eno16777736 #keepalived所配置的接口
virtual_router_id 88 #VRID
priority 100 #优先级
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}

virtual_ipaddress {
10.1.88.88/16 dev eno16777736 label eno16777736:0 #VIP
}

track_script {
chk_down
}

notify_master "/etc/keepalived/notify.sh master"
notify_backup "/etc/keepalived/notify.sh backup"
notify_fault "/etc/keepalived/notify.sh fault"
}

virtual_server 10.1.88.88 80 { #配置虚拟服务器
delay_loop 3
lb_algo rr
lb_kind DR
protocol TCP

sorry_server 127.0.0.1 80 #当所有realserver宕机后，则启用sorry_server

real_server 10.1.68.5 80 { #realserver配置
weight 1
HTTP_GET { #realserver健康状态检测
url {
path /
status_code 200
}

connect_timeout 1
nb_get_retry 3
delay_before_retry 1
}
}

real_server 10.1.68.6 80 {
weight 1
HTTP_GET {
url {
path /
status_code 200
}

connect_timeout 1
nb_get_retry 3
delay_before_retry 1
}
}
}

keepalived backup配置：
global_defs {
notification_email {
root@localhost
}
notification_email_from keepalived@localhost
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id node1
}

vrrp_script chk_down {
script "[[ -f /etc/keepalived/down ]] && exit 1 || exit 0"
interval 2
weight -6
}

vrrp_instance VI_1 {
state BACKUP #配置bakup服务器state为BACKUP
interface eno16777736
virtual_router_id 88
priority 98 #优先级为98，比master低
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}

virtual_ipaddress {
10.1.88.88/16 dev eno16777736 label eno16777736:0
}

track_script {
chk_down
}

notify_master "/etc/keepalived/notify.sh master"
notify_backup "/etc/keepalived/notify.sh backup"
notify_fault "/etc/keepalived/notify.sh fault"
}

virtual_server 10.1.88.88 80 {
delay_loop 3
lb_algo rr
lb_kind DR
protocol TCP

sorry_server 127.0.0.1 80

real_server 10.1.68.5 80 {
weight 1
HTTP_GET {
url {
path /
status_code 200
}

connect_timeout 1
nb_get_retry 3
delay_before_retry 1
}
}

real_server 10.1.68.6 80 {
weight 1
HTTP_GET {
url {
path /
status_code 200
}

connect_timeout 1
nb_get_retry 3
delay_before_retry 1
}
}
}

在两台调度器上面配置httpd，用于sorry_server

在两台前端调度器上同时启动keepalived
service keepalived start #master
service keepalived start #backup

此时两台调度器已经同时生成了ipvs规则

此时VIP已经在master的网卡接口上

4.测试

模拟其中一台调度器故障，VIP立即漂移至backup调度器，不影响调度

其中有一台故障可正常调度至另一台realserver

后端realserver全部故障，此时sorry_server服务器响应

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