一、keepalived基于服务器nginx挂了，不会自动切换
1.1 书写脚本（时刻检查nginx的状态，如果nginx关闭，keepalived也关闭）
[root@lb01 /server/scripts]# cat check-ngx.sh
#!/bin/bash
count=`ps -ef|grep nginx|grep -v grep|wc -l`
if [ $count -eq 0 ];then
systemctl stop keepalived
fi
注：脚本名字不要包含监控对象的名字
1.2 通过keepalived运行检查nginx服务的脚本
1>给脚本check-ngx.sh 一个执行权限
[root@lb01 ~]# chmod +x /server/scripts/check-ngx.sh
[root@lb01 ~]# ll /server/scripts/check-ngx.sh
-rwxr-xr-x 1 root root 116 Jun 17 09:15 /server/scripts/check-ngx.sh
[root@lb01 ~]#
1.3 配置keepalived
[root@lb01 ~]# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived
……
vrrp_script check_ngx {
script /server/scripts/check-ngx.sh
interval 2
weight 1
}
vrrp_instance VI_1 {
……
track_script{
check_ngx
}
}
[root@lb01 ~]#
1.4 重启keepalived
systemctl restart keepalived.service
1.5测试
\\lb01上
[root@lb01 ~]# ip a|grep 0.3
inet 10.0.0.3/24 scope global secondary eth0:1
[root@lb01 ~]# systemctl stop nginx
[root@lb01 ~]# ip a|grep 0.3
[root@lb01 ~]# \\\虚拟ip飘逸走了
\\lb02上
[root@lb02 ~]# ip a|grep 0.3
inet 10.0.0.3/24 scope global secondary eth0:1
\\\回到lb01上
[root@lb01 ~]# systemctl start nginx
[root@lb01 ~]# ip a|grep 0.3
[root@lb01 ~]# systemctl start keepalived.service
[root@lb01 ~]# ip a|grep 0.3 \\虚拟IP自动飘逸回来
inet 10.0.0.3/24 scope global secondary eth0:1
二、keepalived双主模式
目的：减轻负载均衡的压力
2.1 keepalived双主模式配置
分别重启keepalived服务
\\\lb01
[root@lb01 /etc/keepalived]# systemctl restart keepalived.service [root@lb01 /etc/keepalived]# ip a |egrep "0.3|0.4"
inet 10.0.0.3/24 scope global secondary eth0:1
\\\\lb02
[root@lb02 /etc/keepalived]# systemctl restart keepalived.service [root@lb02 /etc/keepalived]# ip a |egrep "0.3|0.4"
keepalived双主模式配置
\\\\lb01的keepalived双主配置文件
! Configuration File for keepalived
global_defs {
router_id lb01
}
vrrp_script jiancha {
script "/server/scripts/jiancha.sh"
interval 2
weight 1
}
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 label eth0:1
}
track_script {
jiancha
}
}
vrrp_instance VI_2 {
state BACKUP
interface eth0
virtual_router_id 52
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
10.0.0.4/24 dev eth0 label eth0:2
}
}
\\\\\\\lb02的keepalived双主配置文件
! Configuration File for keepalived
global_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 label eth0:1
}
}
vrrp_instance VI_2 {
state MASTER
interface eth0
virtual_router_id 52
priority 150
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
10.0.0.4/24 dev eth0 label eth0:2
}
}
让lb01和lb02的nginx配置文件相同
vim /etc/nginx/nginx.conf :
upstream web_pools {
server 10.0.0.7:80 weight=1 max_fails=3 fail_timeout=10s;
server 10.0.0.8:80 weight=1 max_fails=3 fail_timeout=10s;
}
# include /etc/nginx/conf.d/*.conf;
server {
listen 80;
server_name www.oldboy.com;
location / {
proxy_pass http://web_pools;
proxy_set_header Host $host;
proxy_set_header X-Forwarded-For $remote_addr;
}
}
server {
listen 80;
server_name blog.oldboy.com;
location / {
proxy_pass http://web_pools;
proxy_set_header Host $host;
proxy_set_header X-Forwarded-For $remote_addr;
}
}
2.1 在命令行curl测试是否正常
\\\lb01
[root@lb01 ~]# curl 10.0.0.3
web02 www.oldboy.com
[root@lb01 ~]# curl 10.0.0.3
web01 www.oldboy.com
[root@lb01 ~]# curl 10.0.0.4
web02 www.oldboy.com
[root@lb01 ~]# curl 10.0.0.4
web01 www.oldboy.com
[root@lb01 ~]#
\\\lb02
[root@lb02 ~]# curl 10.0.0.3
web02 www.oldboy.com
[root@lb02 ~]# curl 10.0.0.3
web01 www.oldboy.com
[root@lb02 ~]# curl 10.0.0.4
web02 www.oldboy.com
[root@lb02 ~]# curl 10.0.0.4
web01 www.oldboy.com
[root@lb02 ~]#
2.1 在浏览器进行测试
1>先在Windows本地hosts文件中配置解析
10.0.0.3 www.oldboy.com
10.0.0.4 blog.oldboy.com
2>浏览器测试
2.1 测试高可用是否正常
假如将其中1台lb01关机，然后测试www.oldboy.com和blog.oldboy.com在浏览器是否还能正常显示
三、每个域名绑定对应ip
3.1 修改nginx配置
3.2 重启服务
重启服务报Cannot assign requested address的错误
nginx无法把本地不存在的ip地址进行绑定
[root@lb01 ~]# nginx -t
nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
nginx: [emerg] bind() to 10.0.0.7:80 failed (99: Cannot assign requested address) \\不能分配的请求ip地址
nginx: configuration file /etc/nginx/nginx.conf test failed
解决：修改内核参数
在/etc/sysctl.conf文件中，追加net.ipv4.ip_nonlocal_bind = 1
内核生效：sysctl -p
[root@lb01 ~]# cat /etc/sysctl.conf
……
net.ipv4.ip_nonlocal_bind = 1
[root@lb01 ~]# sysctl -p
net.ipv4.ip_nonlocal_bind = 1
[root@lb01 ~]#
注：执行net.ipv4.ip_nonlocal_bind = 1，背后修改了哪里？
[root@lb01 ~]# #net.ipv4.ip_nonlocal_bind
[root@lb01 ~]# # /proc/sys/
[root@lb01 ~]# #net.ipv4.ip_nonlocal_bind
[root@lb01 ~]# cat /proc/sys/net/ipv4/ip_nonlocal_bind \\修改的是这里
1
四、keepalived高可用故障案例
脑裂/裂脑
原因：
1>SELinux/防火墙可以开启
2>高可用服务器对之间心跳线链路故障，导致无法正常通信
3>高可用服务器对上心跳网卡地址等信息配置不正确，导致发送心跳失败。
解决：
1>两条心跳线路
2>只要备任务主挂了，我让你直接挂了
3>书写一个脚本，发送脑裂发送邮件
脚本在哪里写？
备节点
检查什么？
备节点只要出现VIP，我就报警发邮件
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