1.Keepalived高可用概述
1.什么是高可用
什么是高可用, 一般指2台机器启动着相同的业务系统,当有一台机器down机了, 另外一台服务器能快速的接管, 对于访问的用户是无感知的。
2.高可用使用场景
那么高可用使用在什么场景，业务系统需要保证7x24小时不DOWN机, 作为业务来说随时都可用, 让你的业务系统更顽强。
2.Keepalived高可用安装
1.环境准备
| 服务器系统 | 角色 | 外网IP | 内网IP |
|---|---|---|---|
| CentOS 7.5 | keepalived-master | eth0:10.0.0.5 | eth1:172.16.1.5 |
| CentOS 7.5 | keepalived-slave | eth0:10.0.0.6 | eth1:172.16.1.6 |
2.在lb01与lb02上分别安装keepalived软件
[root@lb01 ~]# yum install keepalived -y[root@lb02 ~]# yum install keepalived -y
3.配置lb01, keepalived-master
[root@lb01 ~]# cat /etc/keepalived/keepalived.confglobal_defs {
router_id lb01
}
vrrp_instance VI_1 {
state MASTER interface eth0
virtual_router_id 51 priority 150 advert_int 1 authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress { 10.0.0.3/24 dev eth0
}
}4.配置lb02, keepalived-backup
[root@lb02 ~]# cat /etc/keepalived/keepalived.confglobal_defs {
router_id lb02
}
vrrp_instance VI_1 {
state BACKUP interface eth0
virtual_router_id 51 priority 100 advert_int 1 authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress { 10.0.0.3/24 dev eth0
}
}5.对比keepalived的master与backup配置的区别
| Keepalived配置区别 | Master配置 | Backup节配置 |
|---|---|---|
| route_id(唯一标识) | route_id lb01 | route_id lb02 |
| state(角色状态) | state Master | state Backup |
| priority(竞选优先级) | priority 150 | priority 100 |
6.启动keepalived
#lb01[root@lb01 ~]# systemctl enable keepalived[root@lb01 ~]# systemctl start keepalived#lb02[root@lb02 ~]# systemctl enable keepalived[root@lb02 ~]# systemctl start keepalived
7.检查keepalived的虚拟IP地址是否漂移
在lb01上进行如下操作
# lb01存在vip地址[root@lb01 ~]# ip addr |grep 10.0.0.3 inet 10.0.0.3/24 scope global secondary eth0# 停止lb01上的keepalived, 检测vip已不存在[root@lb01 ~]# systemctl stop keepalived[root@lb01 ~]# ip addr |grep 10.0.0.3
在lb02上进行如下操作
[root@lb02 ~]# ip addr|grep 10.0.0.3 inet 10.0.0.3/24 scope global secondary eth0
lb01重新启动keepalived,发现地址被重新接管
[root@lb01 ~]# systemctl start keepalived[root@lb01 ~]# ip addr |grep 10.0.0.3 inet 10.0.0.3/24 scope global secondary eth0
3.Keepalived高可用配置
4.keepalived高可用列脑
由于某些原因，导致两台keepalived高可用服务器在指定时间内，无法检测到对方的心跳消息，各自取得资源及服务的所有权，而此时的两台高可用服务器又都还活着。
服务器网线松动等网络故障
服务器硬件故障发生损坏现象而崩溃
备节点开启firewalld防火墙
Nginx服务死掉等
1.可以ping通主，备节点还有VIP就认为列脑
[root@lb02 ~]# cat check_split_brain.sh#!/bin/shlb01_vip=10.0.0.3lb01_ip=10.0.0.5while true;do ping -c 2 -W 3 $lb01_ip &>/dev/null if [ $? -eq 0 -a `ip add|grep "$lb01_vip"|wc -l` -eq 1 ];then echo "ha is split brain.warning." else echo "ha is ok" fisleep 5done
2.如果Nginx宕机Keepalived是不会进行切换, 需要写一个脚本检测Nginx的存活状态, 如果不存活则kill nginx和keepalived.
# 编写配置文件[root@lb01 ~]# mkdir /server/scripts[root@lb01 ~]# vim /server/scripts/check_web.sh#!/bin/shwhile true;donginxpid=$(ps -C nginx --no-header|wc -l)if [ $nginxpid -eq 0 ];then systemctl start nginx sleep 5 nginxpid=$(ps -C nginx --no-header|wc -l) if [ $nginxpid -eq 0 ];then systemctl stop keepalived exit 1 fifi sleep 5done[root@lb01 ~]# chmod +x /server/scripts/check_web.sh
在keepalived配置文件中调用此脚本，lb01与lb02都需操作
[root@lb01 ~]# cat /etc/keepalived/keepalived.confglobal_defs {
router_id LVS_01
}
vrrp_script check_web {
script "/server/scripts/check_web.sh"
interval 2
weight 50}
vrrp_instance VI_1 {
state MASTER interface ens33
virtual_router_id 51 priority 150 advert_int 1 authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress { 10.0.0.3/24 dev ens33
}
track_script {
check_web
}
}5.keepalived高可用日志
[root@lb01 ~]#sed -i '14 s#KEEPALIVED_OPTIONS="-D"#KEEPALIVED_OPTIONS="-D -d -S 0"#g' /etc/sysconfig/keepalived #指定文件接收Keepalived服务日志[root@lb-node1 conf]# echo -e "local0.* \t /var/log/keepalived.log" >>/etc/rsyslog.conf #配置至rsyslog[root@lb-node1 conf]# tail -1 /etc/rsyslog.conf #检查是否配置成功local0.*/var/log/keepalived.log [root@lb-node1 conf]# /etc/init.d/rsyslog restart #重新启动rsyslogShutting down system logger: [ OK ] Starting system logger: [ OK ]