keepalived实现nginx高可用
之前发过一篇使用keepalived实现nginx负载均衡的高可用，当时使用的是两台nginx，这次使用三台nginx来做个实验。
环境
zabbix-server 192.168.186.10
zabbix-agent-1 192.168.186.11
zabbix-agent-2 192.168.186.12
VIP 192.168.186.100
(刚好在做zabbix，所以直接在zabbix的机器上安装几个nginx进行测试)
安装nginx（所有机器）
[root@zabbix-server ~]# systemctl -y install nginx
[root@zabbix-agent-1 ~]# systemctl -y install nginx
[root@zabbix-agent-2 ~]# systemctl -y install nginx
修改配置文件（所有nginx）（非必须）
【因为我的机器上的80端口已经被使用了，所以我改一下端口】
...
listen 8880 default_server;
listen [::]:8880 default_server;
server_name _;
root /usr/share/nginx/html;
...
修改nginx默认网页内容
[root@zabbix-server ~]# echo `hostname` > /usr/share/nginx/html/index.html
[root@zabbix-agent-1 ~]# echo `hostname` > /usr/share/nginx/html/index.html
[root@zabbix-agent-2 ~]# echo `hostname` > /usr/share/nginx/html/index.html
启动nginx服务并测试
[root@zabbix-server ~]# systemctl start nginx
[root@zabbix-agent-1 ~]# systemctl start nginx
[root@zabbix-agent-2 ~]# systemctl start nginx
[root@zabbix-server ~]# curl 127.0.0.1:8880
zabbix-server
[root@zabbix-agent-1 ~]# curl 127.0.0.1:8880
zabbix-agent-1
[root@zabbix-agent-2 ~]# curl 127.0.0.1:8880
zabbix-agent-2
安装keepalived（所有机器）
[root@zabbix-server ~]# systemctl -y install keepalived
[root@zabbix-agent-1 ~]# systemctl -y install keepalived
[root@zabbix-agent-2 ~]# systemctl -y install keepalived
配置keepalived(所有机器都一样)
! Configuration File for keepalived
global_defs {
notification_email {
[email protected]
[email protected]
[email protected]
}
notification_email_from [email protected]
smtp_server 192.168.200.1
smtp_connect_timeout 30
router_id LVS_DEVEL
vrrp_skip_check_adv_addr
# vrrp_strict
vrrp_garp_interval 0
vrrp_gna_interval 0
}
vrrp_script nginx {
script "/keepalived/curl_nginx.sh"
interval 3
weight -30
fall 2
rise 1
}
vrrp_instance VI_1 {
state BACKUP
interface ens33
virtual_router_id 51
priority 100
advert_int 1
nopreempt
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.186.100
}
track_script {
nginx
}
}
#之前配置两台keepalived的时候，只需要在某一台配置检测脚本，现在配置三台，直接把所有配置文件都设置成一样的，这样可以实现三台ngnix之间的服务可以自由切换。
检测脚本（所有机器都要有）
[root@zabbix-server ~]# mkdir /keepalived/
[root@zabbix-server ~]# vim /keepalived/curl_nginx.sh
#!/bin/bash
curl 127.0.0.1:8880||systemctl stop keepalived
[root@zabbix-server ~]# chmod +x /keepalived/curl_nginx.sh -R
#脚本比较简陋，实际生产中不要使用这种脚本，测试可以使用
启动所有keepalived服务
[root@zabbix-server ~]# systemctl start keepalived.service
[root@zabbix-agent-1 ~]# systemctl start keepalived.service
[root@zabbix-agent-2 ~]# systemctl start keepalived.service
测试
[root@zabbix-server ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 00:0c:29:fe:92:0c brd ff:ff:ff:ff:ff:ff
inet 192.168.186.10/24 brd 192.168.186.255 scope global ens33
valid_lft forever preferred_lft forever
inet 192.168.186.100/32 scope global ens33
valid_lft forever preferred_lft forever
inet6 fe80::20c:29ff:fefe:920c/64 scope link
valid_lft forever preferred_lft forever
#VIP现在在master上
[root@zabbix-server ~]# curl 192.168.186.100:8880
zabbix-server
#访问VIP，可以看出，确实是访问到了server的nginx上。
#关掉server上的nginx，再次访问。
[root@zabbix-server ~]# systemctl stop nginx
[root@zabbix-server ~]# curl 192.168.186.100:8880
curl: (7) Failed connect to 192.168.186.100:8880; Connection refused
[root@zabbix-server ~]# curl 192.168.186.100:8880
zabbix-agent-2
#可以看到，在VIP飘移的过程中，有一小段时间服务不可用
#后面VIP成功飘移到agent-2上
#反复对所有机器上的nginx进行启动关闭，可以看到服务一直都是可用的（除了切换VIP的时间）
#注意：重启nginx后，也要手动启动keepalived。
实验完毕！
实际上不会这么使用，上述场景只是做个实验。