HAProxy 高级应用
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概述：
本章将继续介绍haproxy的一些其他应用，具体内容如下：
- use_backend <backend> 后端主机调用：
- haproxy中tcp模式的应用；
- haproxy中listen的应用
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HAProxy配置参数---代理配置段：
12.后端主机调用：
★use_backend <backend> [{if | unless} <condition>]
---Switch to a specific backend if/unless an ACL-based condition is matched.（满足acl条件时就调度到指定的后端主机）
示例：
使用use_backend实现动静分离
HAProxy的tcp模式应用
实验：
使用haproxy调度后端主机的SSH服务
实验环境描述：
- 三台虚拟主机，一台作为haproxy的调度器，另外两台作为后端的原始web服务器；
- haproxy调度器有两块网卡，一块作为外网网卡，负责接收用户的请求，一块为内网网卡，负责与内网的后端原始web服务器通信；（要打开核心件转发功能）
IP地址规划：
- 两台后端主机使用内网地址RS1(192.168.111.128);RS2(192.168.111.129)，与haproxy的内网网卡基于VMnet1通信；
- haprosy外网地址ip（10.1.252.153）；内网地址ip(192.168.111.130)
实验过程如下：
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1.编辑haproxy的配置文件，定义前端frontend和后端backend具体如下：
frontend ssh bind *:22022 //为了和本机区分使用22022 mode tcp default_backend sshsrvs backend sshsrvs balance leastconn //使用最少连接算法 server ssh1 192.168.111.128:22 check server ssh2 192.168.111.129:22 check
2.重载haproxy服务，然后登录SSH服务，可以发现可以正常连接到后端的两台原始服务器，如下：
[[email protected] haproxy]# ssh -p 22022 10.1.252.153 The authenticity of host ‘[10.1.252.153]:22022 ([10.1.252.153]:22022)‘ can‘t be established. ECDSA key fingerprint is cb:36:da:6b:15:d6:60:25:a7:28:f1:bf:b3:22:ce:c0. Are you sure you want to continue connecting (yes/no)? yes [[email protected] ~]# ifconfig eno16777736: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.111.129 netmask 255.255.255.0 broadcast 192.168.111.255 inet6 fe80::20c:29ff:feca:6ef1 prefixlen 64 scopeid 0x20<link> ether 00:0c:29:ca:6e:f1 txqueuelen 1000 (Ethernet) RX packets 156021 bytes 13141000 (12.5 MiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 24359 bytes 1858526 (1.7 MiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536 inet 127.0.0.1 netmask 255.0.0.0 inet6 ::1 prefixlen 128 scopeid 0x10<host> loop txqueuelen 0 (Local Loopback) RX packets 32 bytes 2720 (2.6 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 32 bytes 2720 (2.6 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 [[email protected] ~]# exit logout Connection to 10.1.252.153 closed. [[email protected] haproxy]# ssh -p 22022 10.1.252.153 The authenticity of host ‘[10.1.252.153]:22022 ([10.1.252.153]:22022)‘ can‘t be established. ECDSA key fingerprint is 56:78:d2:e8:41:b0:62:ad:4f:47:90:75:01:a4:fa:8c. Are you sure you want to continue connecting (yes/no)? yes [[email protected] ~]# ifconfig eno16777736: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.111.128 netmask 255.255.255.0 broadcast 192.168.111.255 inet6 fe80::20c:29ff:fed6:e460 prefixlen 64 scopeid 0x20<link> ether 00:0c:29:d6:e4:60 txqueuelen 1000 (Ethernet) RX packets 157051 bytes 13309701 (12.6 MiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 25174 bytes 1963784 (1.8 MiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536 inet 127.0.0.1 netmask 255.0.0.0 inet6 ::1 prefixlen 128 scopeid 0x10<host> loop txqueuelen 0 (Local Loopback) RX packets 59 bytes 4880 (4.7 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 59 bytes 4880 (4.7 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
HAProxy中listen的应用
1.如上例，我们也可以使用listen将两个单独的forontend和backend整合到一起，如下：
listen ssh bind *:22022 mode tcp balance leastconn server ssh1 192.168.111.128:22 check server ssh2 192.168.111.129:22 check
2.我们也可以将stats统计信息状态页使用listen整合到一起，如下：
listen stats bind *:9527 stats enable stats uri /admin?stats stats realm Stats\ Page\ Area stats auth taotao:xiuxiu stats refresh 5s stats hide-version
3.重载haproxy服务，查看监听的端口9527，如下：
[[email protected] haproxy]# systemctl reload haproxy.service [[email protected] haproxy]# ss -tnl State Recv-Q Send-Q Local Address:Port LISTEN 0 128 127.0.0.1:6012 LISTEN 0 25 *:514 LISTEN 0 128 *:22022 LISTEN 0 128 *:8080 LISTEN 0 128 *:80 LISTEN 0 128 *:22 LISTEN 0 128 *:9527
4.在浏览器中访问stats统计页状态信息如下：
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