Keepalived高可用LVS

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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：
Keepalived 高可用 LVS

1. 在两台 Real Server 上配置 web 服务

Keepalived 高可用 LVS

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
}
}
}