本文主要是介绍Mycat（5）——基于keepalived+haproxy实现Mycat高可用，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
一、高可用架构
keepalived主要是为了保证haproxy的高可用，主要用于监控haproxy是否可用，然后进行故障转移；而haproxy主要用来实现负载均衡。
| 角色 | 服务器 |
|---|---|
| Mycat1 | 192.168.30.130 |
| Mycat2 | 192.168.30.131 |
| haproxy1 | 192.168.30.132 |
| haproxy2 | 192.168.30.133 |
| keepalived1 | 192.168.30.132 |
| keepalived2 | 192.168.30.133 |
| 虚拟IP | 192.168.30.134 |
注：相关服务器已经关闭防护墙和selinux
二、安装haproxy实现负载均衡
安装：
yum install haproxy -y
[root@server3 keepalived]# whereis haproxy
haproxy: /usr/sbin/haproxy /etc/haproxy /usr/share/haproxy /usr/share/man/man1/haproxy.1.gz
修改配置文件/etc/haproxy/haproxy.cfg:
globallog 127.0.0.1 local3 infochroot /var/lib/haproxypidfile /var/run/haproxy.pidmaxconn 10000user haproxygroup haproxydaemon# turn on stats unix socketstats socket /var/lib/haproxy/statsdefaults#mode 修改为tcp 相关option修改为tcp配置或注掉mode tcplog globaloption tcplogoption dontlognull# option http-server-close# option forwardfor except 127.0.0.0/8option redispatchretries 3timeout http-request 10stimeout queue 1mtimeout connect 10stimeout client 1mtimeout server 1m# timeout http-keep-alive 10stimeout check 10smaxconn 10000frontend mycatmode tcpbind *:5001default_backend mycat-backendbackend mycat-backendmode tcpbalance roundrobinserver mycat_1 192.168.30.130:8066 check inter 10sserver mycat_2 192.168.30.131:8066 check inter 10s
启动haproxy
systemctl start haproxy[root@server3 keepalived]# systemctl status haproxy
● haproxy.service - HAProxy Load BalancerLoaded: loaded (/usr/lib/systemd/system/haproxy.service; disabled; vendor preset: disabled)Active: active (running) since 日 2021-04-25 10:09:12 CST; 22min agoMain PID: 3803 (haproxy-systemd)CGroup: /system.slice/haproxy.service├─3803 /usr/sbin/haproxy-systemd-wrapper -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid├─3805 /usr/sbin/haproxy -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid -Ds└─3806 /usr/sbin/haproxy -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid -Ds4月 25 10:09:12 server3 systemd[1]: Started HAProxy Load Balancer.
4月 25 10:09:12 server3 haproxy-systemd-wrapper[3803]: haproxy-systemd-wrapper: executing /usr/sbin/haproxy -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid -Ds
验证：
mysql -uroot -p123456 -P 5001 -h 192.168.30.132
可以成功登陆。
三、安装keepalived实现故障转移
（一）安装配置keepalived
安装keepalived:
yum install keepalived -y
在/etc/keepalived文件夹下创建haproxy状态检测脚本haproxy_check.sh：
#!/bin/bash
if [ $(ps -C haproxy --no-header | wc -l) -eq 0 ]; then
systemctl start haproxy
fisleep 2
if [ $(ps -C haproxy --no-header | wc -l) -eq 0 ]; then
systemctl stop keepalived
fi
修改keepalived配置文件/etc/keepalived/keepalived.cnf：
keepalived1:
global_defs {router_id k1script_user rootvrrp_skip_check_adv_addrvrrp_garp_interval 0vrrp_gna_interval 0
}vrrp_script chk_haproxy {script "/etc/keepalived/haproxy_check.sh"interval 5weight -20
}vrrp_instance VI_1 {state BACKUPinterface ens33virtual_router_id 51priority 100advert_int 1authentication {auth_type PASSauth_pass 1111}virtual_ipaddress {192.168.30.134}track_script {chk_haproxy}
}
keepalived2：
global_defs {router_id k2script_user rootenable_scrip_securityvrrp_skip_check_adv_addrvrrp_garp_interval 0vrrp_gna_interval 0
}vrrp_script chk_haproxy {script "/etc/keepalived/haproxy_check.sh"interval 5
}vrrp_instance VI_1 {state BACKUPinterface ens33virtual_router_id 51priority 90advert_int 1authentication {auth_type PASSauth_pass 1111}virtual_ipaddress {192.168.30.134}track_script {chk_haproxy}
}
state 都配置为BACKUP，防止MASTER出现抢占的问题。
priority一个是100，一个是90.
启动keepalived：
systemctl start keepalived
此时，虚拟IP在keepalived1中：
[root@server3 keepalived]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00inet 127.0.0.1/8 scope host lovalid_lft forever preferred_lft foreverinet6 ::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 1000link/ether 00:0c:29:45:c6:f5 brd ff:ff:ff:ff:ff:ffinet 192.168.30.132/24 brd 192.168.30.255 scope global noprefixroute ens33valid_lft forever preferred_lft foreverinet 192.168.30.134/32 scope global ens33valid_lft forever preferred_lft foreverinet6 fe80::20c:29ff:fe45:c6f5/64 scope link valid_lft forever preferred_lft foreve
（二）验证故障转移
使用虚拟IP地址访问mycat：
mysql -uroot -p123456 -P 5001 -h 192.168.30.134
- 关闭haproxy
在keepalived1中关闭haproxy，发现haproxy随即被keepalived恢复启动。 - 关闭keepalived
关闭keepalived1中的keepalive，发现虚拟IP转移至keepalived2中：
[root@server4 keepalived]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00inet 127.0.0.1/8 scope host lovalid_lft forever preferred_lft foreverinet6 ::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 1000link/ether 00:0c:29:94:17:de brd ff:ff:ff:ff:ff:ffinet 192.168.30.133/24 brd 192.168.30.255 scope global noprefixroute ens33valid_lft forever preferred_lft foreverinet 192.168.30.134/32 scope global ens33valid_lft forever preferred_lft foreverinet6 fe80::20c:29ff:fe94:17de/64 scope link valid_lft forever preferred_lft forever
[root@server4 keepalived]#
使用虚拟IP可以继续访问mycat
重启keepalived1后，虚拟IP转移至keepalived1中。
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