使用haproxy实现读负载均衡

环境：redhat 7
IP： 192.168.247.140

准备工作：
关闭iptables selinux

安装：

[root@ha01 ~]# yum install -y haproxy
# 版本
[root@ha01 ~]# haproxy -v
HA-Proxy version 1.5.18 2016/05/10
Copyright 2000-2016 Willy Tarreau <willy@haproxy.org>

配置：

mv  /etc/haproxy/haproxy.cfg /etc/haproxy/haproxy.cfg.bak
vi /etc/haproxy/haproxy.cfg
global

    log        127.0.0.1 local2
    chroot     /var/lib/haproxy
    pidfile    /var/run/haproxy.pid
    maxconn    4000
    daemon                                  # 后台运行

defaults

    mode                    tcp
    log                     global
    option                  dontlognull
    option                  redispatch      #当serverId对应的服务器挂掉后，强制定向到其他健康的服务器
    retries                 3               #三次连接失败就认为是服务器不可用，也可以通过后面设置
    timeout http-request    10s
    timeout queue           1m
    timeout connect         10s             #连接超时
    timeout client          1m              #客户端超时
    timeout server          1m              #服务器超时
    timeout http-keep-alive 10s
    timeout check           10s             # 心跳检测超时
    maxconn                 4096            #默认的最大连接数


listen status
    mode http
    bind :8080
    stats enable                        # 开启监控
    stats hide-version                  ## 隐藏版本号
    stats uri     /haproxyadmin?stats   ## http://ip:8080/haproxyadmin?stats
    stats realm   Haproxy\ Statistics
    stats auth    admin:admin           # 用户名密码
    stats admin if TRUE                 #是否开启管理功能，必须跟stats auth命令

frontend  main
    bind *:3306
    default_backend             mysql

backend mysql
    balance    leastconn                # 表示最少连接者先处理
    server s1 192.168.247.122:3306 check port 3306 maxconn 3000 #负载的机器，负载的机器可以有多个，往下排列即可
    server s2 192.168.247.123:3306 check port 3306 maxconn 3000

修改日志系统：

vi /etc/rsyslog.conf

# Provides UDP syslog reception//去掉下面两行注释，开启UDP监听
$ModLoad imudp
$UDPServerRun 514

local2.* /var/log/haproxy.log // 结尾添加此行

启动服务：

# 重启
systemctl restart rsyslog

# 启动
systemctl start haproxy

# 查看日志
tailf /var/log/haproxy.log

查看状态：

[root@ha01 ~]# systemctl status haproxy
● haproxy.service - HAProxy Load Balancer
   Loaded: loaded (/usr/lib/systemd/system/haproxy.service; enabled; vendor preset: disabled)
   Active: active (running) since 二 2021-07-27 22:21:31 CST; 4s ago
 Main PID: 28200 (haproxy-systemd)
   CGroup: /system.slice/haproxy.service
           ├─28200 /usr/sbin/haproxy-systemd-wrapper -f /etc/haproxy/haproxy....
           ├─28201 /usr/sbin/haproxy -f /etc/haproxy/haproxy.cfg -p /run/hapr...
           └─28202 /usr/sbin/haproxy -f /etc/haproxy/haproxy.cfg -p /run/hapr...

7月 27 22:21:31 ha01 systemd[1]: Started HAProxy Load Balancer.
7月 27 22:21:31 ha01 systemd[1]: Starting HAProxy Load Balancer...
7月 27 22:21:31 ha01 haproxy-systemd-wrapper[28200]: haproxy-systemd-wrapper...
Hint: Some lines were ellipsized, use -l to show in full.

测试连接：

[root@mysql2 ~]# for (( i=0;i<10;i++ ));
> do
> mysql -uroot -proot1234 -h192.168.247.140 -P3306 -e "select @@server_id"
> done
mysql: [Warning] Using a password on the command line interface can be insecure.
+-------------+
| @@server_id |
+-------------+
|      247122 |
+-------------+
mysql: [Warning] Using a password on the command line interface can be insecure.
+-------------+
| @@server_id |
+-------------+
|      247123 |
+-------------+
mysql: [Warning] Using a password on the command line interface can be insecure.
+-------------+
| @@server_id |
+-------------+
|      247122 |
+-------------+
mysql: [Warning] Using a password on the command line interface can be insecure.
+-------------+
| @@server_id |
+-------------+
|      247123 |
+-------------+
mysql: [Warning] Using a password on the command line interface can be insecure.
+-------------+
| @@server_id |
+-------------+
|      247122 |
+-------------+
mysql: [Warning] Using a password on the command line interface can be insecure.
+-------------+
| @@server_id |
+-------------+
|      247123 |
+-------------+
mysql: [Warning] Using a password on the command line interface can be insecure.
+-------------+
| @@server_id |
+-------------+
|      247122 |
+-------------+
mysql: [Warning] Using a password on the command line interface can be insecure.
+-------------+
| @@server_id |
+-------------+
|      247123 |
+-------------+
mysql: [Warning] Using a password on the command line interface can be insecure.
+-------------+
| @@server_id |
+-------------+
|      247122 |
+-------------+
mysql: [Warning] Using a password on the command line interface can be insecure.
+-------------+
| @@server_id |
+-------------+
|      247123 |
+-------------+