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HAProxy是 七层代理 ，在使甠HAProxy后，在MySQL上 看不到Apps的源IP地址 ，看到的是HAProxy地址，而 MySQL的权限访问设置是和IP地址有关 ，这样就导致了MySQL无法 针对应用 进行区分权限了，所以使用的时候要注意。
1. HAProxy的安装
Shell> yum install haproxy
2. HAProxy的配置
2.1. haproxy.cfg
将以下配置文件保存为 /etc/haproxy/haproxy.cfg
[root@mysql3 haproxy]# cat /etc/haproxy/haproxy.cfg
# this config needs haproxy-1.1.28 or haproxy-1.2.1
global
log 127.0.0.1 local0
log 127.0.0.1 local1 notice
#log loghost local0 info
maxconn 4096
chroot /usr/share/haproxy
uid 99
gid 99
daemon
#debug
#quiet
defaults
log global
mode http
#option httplog
option dontlognull
retries 3
option redispatch
maxconn 2000
contimeout 5000
clitimeout 50000
srvtimeout 50000
# 绑定的IP和端口
listen MySQL 10.100.25.42:3308
mode tcp
maxconn 200
# 负载均衡算法是 轮询
balance roundrobin
# 通过mysql连接去检测mysql是否可以访问
option mysql-check user haproxy_check
server mysql_1 10.100.25.40:3308 inter 1s rise 2 fall 2
server mysql_3 10.100.25.41:3307 inter 1s rise 2 fall 2
server mysql_3 10.100.25.41:3308 inter 1s rise 2 fall 2
# 自带的监控服务器的配置
listen admin_status
mode http
bind 0.0.0.0:8899
option httplog
log global
stats enable
stats refresh 10s
stats hide-version
stats realm Haproxy\ Statistics
stats uri /
# 监控的用户名和密码
stats auth myadmin:myadmin
stats admin if TRUE
2.2. 添加haproxy_check用户
将以下SQL语句在Master端执行，通过复制功能，传递到Slave上。
drop user haproxy_check@'XX';
create user haproxy_check@'XX';
grant usage on *.* to haproxy_check@'XX';
2.3. 配置日志
注意：该方法仅在 CentOS 6.X 上使用， CentOS 7.x 安装 HAProxy 后可甠 systemctl status haproxy 进行查看。
将以下文件保存为 /etc/rsyslog.d/49-haproxy.conf
# Create an additional socket in haproxy's chroot in order to allow logging via
# /dev/log to chroot'ed HAProxy processes
$AddUnixListenSocket /var/lib/haproxy/dev/log
$ModLoad imudp
$UDPServerRun 514
local3.* /var/log/haproxy.log
# Send HAProxy messages to a dedicated logfile
if $programname startswith 'haproxy' then /var/log/haproxy.log
&~
然后重启 rsyslog 服务
Shell> service rsyslog restart
Shutting down system logger: [ OK ]
Starting system logger: [ OK ]
3. 启动HAProxy
Shell> service haproxy start
[root@mysql3 ~]# netstat -tunlp | grep haproxy
tcp 0 0 0.0.0.0:3308 0.0.0.0:* LISTEN 2583/haproxy
tcp 0 0 0.0.0.0:8899 0.0.0.0:* LISTEN 2583/haproxy
udp 0 0 0.0.0.0:33136 0.0.0.0:* 2583/haproxy
4. HAProxy测试
[root@mysql3 haproxy]# mysql -h 10.100.25.42 -P 3308 -uroot -pmysql -e "show variables like 'server_id'";
mysql: [Warning] Using a password on the command line interface can be insecure.
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| server_id | 22 |
+---------------+-------+
[root@mysql3 haproxy]# mysql -h 10.100.25.42 -P 3308 -uroot -pmysql -e "show variables like 'server_id'";
mysql: [Warning] Using a password on the command line interface can be insecure.
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| server_id | 33 |
+---------------+-------+
[root@mysql3 haproxy]# mysql -h 10.100.25.42 -P 3308 -uroot -pmysql -e "show variables like 'server_id'";
mysql: [Warning] Using a password on the command line interface can be insecure.
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| server_id | 44 |
+---------------+-------+
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