Keepalived概述
概念
keepalived 是Linux下一个轻量级的高可用解决方案
主要是通过虚拟路由冗余协议(VRRP)来实现高可用功能
Virtual Router Redundancy Protocol
起初就是为了补充LVS功能而设计的，用于监控LVS集群内后端真实服务器状态
后来加入了VRRP的功能，它出现的目的是为了解决静态路由出现的单点故障问题
功能
LVS规则管理
LVS集群真实服务器状态监测
管理VIP
Keepalived实现web高可用
实验环境
web1：eth0->192.168.88.100/24
web2：eth0->192.168.88.200/24
配置Keepalived高可用集群
# 安装Keepalived软件
[root@pubserver cluster]# vim 08_inst_web_kp.yml
---
- name: install keepalive on webservers
hosts: webservers
tasks:
- name: install keepalived #安装软件
yum:
name: keepalived
state: present
[root@pubserver cluster]# ansible-playbook 08_inst_web_kp.yml
# 配置Keepalived集群
[root@web1 ~]# vim /etc/keepalived/keepalived.conf
1 ! Configuration File for keepalived
2
...
11 smtp_connect_timeout 30
12 router_id web1 #设置集群节点唯一标识符
13 vrrp_iptables #与vrrp_strict连用时自动放行iptables规则
14 vrrp_skip_check_adv_addr
15 vrrp_strict #严格遵守VRRP协议，将iptables默认规则设置为拒绝
16 vrrp_garp_interval 0
17 vrrp_gna_interval 0
18 }
19
20 vrrp_instance VI_1 {
21 state MASTER #状态
22 interface eth0 #监听网卡
23 virtual_router_id 51 #虚拟路由器唯一表示，范围0-255
24 priority 100 #优先级
25 advert_int 1 #心跳包频率
26 authentication {
27 auth_type PASS #认证类型为共享密码
28 auth_pass 1111 #集群内节点认证密码相同
29 }
30 virtual_ipaddress {
31 192.168.88.80/24 dev eth0 label eth0:1 #VIP地址及绑定网卡和虚接口标签
32 }
33 }
[root@web2 ~]# vim /etc/keepalived/keepalived.conf
1 ! Configuration File for keepalived
2
3 global_defs {
...
11 smtp_connect_timeout 30
12 router_id web2 #集群节点唯一标识
13 vrrp_iptables #放行iptables规则
14 vrrp_skip_check_adv_addr
15 vrrp_strict
16 vrrp_garp_interval 0
17 vrrp_gna_interval 0
18 }
19
20 vrrp_instance VI_1 {
21 state BACKUP #状态
22 interface eth0
23 virtual_router_id 51
24 priority 50 #优先级值低于master
25 advert_int 1
26 authentication {
27 auth_type PASS
28 auth_pass 1111
29 }
30 virtual_ipaddress {
31 192.168.88.80/24 dev eth0 label eth0:1
32 }
33 }
# 启服务
[root@web1 ~]# systemctl start keepalived.service
[root@web2 ~]# systemctl start keepalived.service
# 验证VIP绑定情况
[root@web1 ~]# ip a s | grep 192.168 #web1主机绑定vip
inet 192.168.88.15/32 brd 192.168.88.15 scope global lo:0
inet 192.168.88.100/24 brd 192.168.88.255 scope global noprefixroute eth0
inet 192.168.88.80/24 scope global secondary eth0:1
[root@web2 ~]# ip a s | grep 192.168 #web2主机未绑定vip
inet 192.168.88.15/32 brd 192.168.88.15 scope global lo:0
inet 192.168.88.200/24 brd 192.168.88.255 scope global noprefixroute eth0
# 测试高可用
[root@client ~]# curl http://192.168.88.80 #访问VIP得到web1节点首页内容
Welcome to web1
[root@web1 ~]# systemctl stop keepalived.service #模拟web1节点故障
[root@client ~]# curl http://192.168.88.80 #访问VIP得到web2节点首页内容
Welcome to web2
[root@web2 ~]# ip a s | grep 192.168 #确认web2主机绑定VIP
inet 192.168.88.15/32 brd 192.168.88.15 scope global lo:0
inet 192.168.88.200/24 brd 192.168.88.255 scope global noprefixroute eth0
inet 192.168.88.80/24 scope global secondary eth0:1
[root@web1 ~]# systemctl start keepalived.service #模拟web1节点修复
[root@web1 ~]# ip a s | grep 192.168 #确认VIP被web1抢占
inet 192.168.88.15/32 brd 192.168.88.15 scope global lo:0
inet 192.168.88.100/24 brd 192.168.88.255 scope global noprefixroute eth0
inet 192.168.88.80/24 scope global secondary eth0:1
[root@web2 ~]# ip a s | grep 192.168 #确认VIP被web2释放
inet 192.168.88.15/32 brd 192.168.88.15 scope global lo:0
inet 192.168.88.200/24 brd 192.168.88.255 scope global noprefixroute eth0
配置Keepalived关联节点服务
配置高可用的web集群时，Keepalived只为服务器提供了VIP
Keepalived不知道服务器上运行了哪些服务
MASTER服务器可以通过跟踪脚本监视本机的80端口，一旦本机80端口失效，则将VIP切换至BACKUP服务器
Keepalived对脚本的要求是，退出码为0表示访问成功；退出码为1表示失败
## 解决Keepalived关联节点服务
# 编写服务检查脚本
[root@web1 ~]# vim /etc/keepalived/check_http.sh
#!/bin/bash
ss -antpul | grep -q nginx && exit 0 || exit 1
[root@web1 ~]# chmod +x /etc/keepalived/check_http.sh
# 配置Keepalived关联服务
[root@web1 ~]# vim /etc/keepalived/keepalived.conf
[root@web1 ~]# cat -n /etc/keepalived/keepalived.conf
1 ! Configuration File for keepalived
2
...
18 }
19
20 vrrp_script chk_http_port { #定义监控监本，手工编辑本段内容
21 script "/etc/keepalived/check_http.sh" #定义检测脚本位置
22 interval 2 #定义脚本执行时间
23 }
24
25 vrrp_instance VI_1 {
26 state MASTER
27 interface eth0
28 virtual_router_id 51
29 priority 100
30 advert_int 1
31 authentication {
32 auth_type PASS
33 auth_pass 1111
34 }
35 virtual_ipaddress {
36 192.168.88.80/24 dev eth0 label eth0:1
37 }
38 track_script { #引用脚本，手工编写本段
39 chk_http_port
40 }
41 }
[root@web1 ~]# systemctl restart keepalived.service
[root@web2 ~]# scp root@192.168.88.100:/etc/keepalived/check_http.sh /etc/keepalived/
[root@web2 ~]# chmod +x /etc/keepalived/check_http.sh
[root@web2 ~]# vim /etc/keepalived/keepalived.conf
[root@web2 ~]# cat -n /etc/keepalived/keepalived.conf
1 ! Configuration File for keepalived
2
...
18 }
19
20 vrrp_script chk_http_port { #定义监控脚本
21 script "/etc/keepalived/check_http.sh"
22 interval 2
23 }
24
25 vrrp_instance VI_1 {
...
35 virtual_ipaddress {
36 192.168.88.80/24 dev eth0 label eth0:1
37 }
38 track_script { #引用监控脚本
39 chk_http_port
40 }
41 }
[root@web2 ~]# systemctl restart keepalived.service
# 测试高可用配置
[root@web1 ~]# ip a s | grep 88.80 #确认VIP绑定在web1
inet 192.168.88.80/24 scope global secondary eth0:1
[root@client ~]# curl http://192.168.88.80 #访问测试得到web1首页内容
Welcome to web1
[root@web1 ~]# systemctl stop nginx.service #模拟web1故障
[root@web1 ~]# ip a s | grep 88.80 #确认web1释放VIP
[root@client ~]# curl http://192.168.88.80 #访问测试得到web2首页内容
Welcome to web2
[root@web2 ~]# ip a s | grep 88.80 #确认VIP绑定于web2
inet 192.168.88.80/24 scope global secondary eth0:1
[root@web1 ~]# systemctl start nginx.service #模拟web1故障修复
[root@web1 ~]# ip a s | grep 88.80 #确认VIP绑定于web1
inet 192.168.88.80/24 scope global secondary eth0:1
