菜鸟学Linux 第093篇笔记 keepalived
内容总览
keepalived介绍
配置keepalived的ipvs功能
keepalived的几个问题解决方法
keepalived
它可以实现ipvs的功能，并且还可以实现前端的ipvs-server高可用，以及后台realserver
的健康状态检查，而不像ipvs需要用户自己来写脚本完成后台的realserver健康状态检测
HA的底层功能
ipvs --> ha 为ipvs提供高可用功能ha
ipvs --> 可以使VIP在节点间流转
vrrp 虚拟路由冗余协议
能将多个物理接口虚拟成一个物理接口，用来解决局域网网关的冗余
配置keepalived 使其实现ipvs的功能，可以检测后台realserver的状态
准备工作
两台realserver节点 192.168.11.105 192.168.11.106
/proc/sys/net/ipv4/conf/all/arp_announce=2
/proc/sys/net/ipv4/conf/all/arp_ignore=1
/proc/sys/net/ipv4/conf/lo/arp_announce=2
/proc/sys/net/ipv4/conf/lo/arp_ignore=1
netstat -tunlp 开启80端口 (httpd)
两台keepalived + ipvsadm节点 192.168.11.101 192.168.11.102
虚拟的IP为192.168.11.100
1. 两台keepalived + ipvsadm节点安装
# yum -y install keepalived ipvsadm(安装ipvsadm软件是为了查看规则)
2. 配置节点的keepalived /etc/keepalived/keepalived.conf
# vim /etc/keepalived/keepalived.conf
修改如下
global_defs {
notification_email {
root@localhost (此项里是添加email地址，当有信息是将通知到此mail里)
}
notification_email_from keepalive@localhost (寄件人)
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_instance VI_1 {
state MASTER
interface eth0
virtual_router_id 51
priority 101
advert_int 1
authentication {
auth_type PASS
auth_pass keepaliveps
}
virtual_ipaddress {
192.168.11.100/24 dev eth0 label eth0:0 （所虚拟的地址）
}
}
virtual_server 192.168.11.100 80 {
delay_loop 6
lb_algo rr
lb_kind DR
nat_mask 255.255.255.0
#persistence_timeout 50
protocol TCP
real_server 192.168.11.105 80 {
weight 1
HTTP_GET { （验证http的方式）
url {
path /
status_code 200
}
connect_timeout 2
nb_get_retry 3
delay_before_retry 1
}
}
real_server 192.168.11.106 80 {
weight 1
HTTP_GET {
url {
path /
status_code 200
}
connect_timeout 2
nb_get_retry 3
delay_before_retry 1
}
}
}
备节点里只需要将此配置文件复制过去然后修改state MASTER 为备份节点即可BACKUP
keepalived的几个问题解决
1. 所有realserver都down，如何处理？
在两台前端ipvs服务器安装httpd 并开启此服务 记得要添加html文档
在配置文件/etc/keepalived/keepalived.conf
virtual_server 192.168.11.100 80 括号里添加sorry_server 127.0.0.1 80
2. 自写监测脚本，完成维护模式切换ipvs-server主备切换
# vim /etc/keepalived/keepalived.conf
在vrrp_instance 添加一段
track_script {
chk_schedown
}
添加一段在末尾
vrrp_script chk_schedown {
script "[[ -f /etc/keepalived/down ]] && exit 1 || exit 0"
interval 1
weight -2
fall 2
rise 1
}
当要测试使其ipvs服务器切换只需要在/etc/keepalived/目录创建一个down文件，查看其是否
会切换
3. 如何在vrrp事务发生时，主备切换时，如何发送警告邮件给指定的管理员？
编写脚本vim /etc/keepalived/notify.sh
#!/bin/bash
#
contact='root@localhost'
Usage() {
echo "Usage: `basename $0` {master|backup|fault} VIP"
}
Notify() {
subject="`hostname`'s state changed to $1"
mailbody="`date "+%F %T"`: `hostname`'s state changed to $1, $VIP floating."
echo $mailbody | mail -s "$subject" $contact
}
VIP=$2
case $1 in
master)
Notify master
;;
backup)
Notify backup
;;
fault)
Notify fault
;;
*)
Usage
exit 1
;;
esac
此脚本可接受参数，当接受到指定的参数时，则会将相应的信息发送给root用户的mailbox里
编辑/etc/keepalived/keepalived.conf
在vrrp_instance 括号里添加
notify_master "/etc/keepalived/notify.sh master 192.168.11.100"
notify_backup "/etc/keepalived/notify.sh backup 192.168.11.100"
notify_fault "/etc/keepalived/notify.sh fault 192.168.11.100"
至此，当主节点和备节点切换时，，则会以邮件形式通知给root
