HAProxy 入门教程

HAProxy是一个免费的负载均衡软件，可以运行于大部分主流的Linux操作系统上。HAProxy提供了L4(TCP)和L7(HTTP)两种负载均衡能力，具备完善的扩展能力, 性能和稳定性都非常好。

HAProxy常用功能:

• 负载均衡：L4和L7两种模式，支持RR/静态RR/LC/IP Hash/URI Hash/URL_PARAM Hash/HTTP_HEADER Hash等丰富的负载均衡算法
• 健康检查：支持TCP和HTTP两种健康检查模式
• 会话保持：对于未实现会话共享的应用集群，可通过Insert Cookie/Rewrite Cookie/Prefix Cookie，以及上述的多种Hash方式实现会话保持
• SSL：HAProxy可以解析HTTPS协议，并能够将请求解密为HTTP后向后端传输
• HTTP请求重写与重定向
• 监控与统计：HAProxy提供了基于Web的统计信息页面，展现健康状态和流量数据。

安装HAProxy:

• Centos

yum -y install haproxy

• Debian/Ubuntu

apt-get -y install haproxy

• Gentoo

emerge -a net-proxy/haproxy

接下来我们准备环境:

Web Server Details:

Server 1:    web1.example.com     192.168.1.101
Server 2:    web2.example.com     192.168.1.102
Server 3:    web3.example.com     192.168.1.103

HAProxy Server: 

HAProxy:     haproxy              192.168.1.12

HAProxy的配置文件为 /etc/haproxy/haproxy.cfg, 默认的内容如下:

global
    log /dev/log    local0
    log /dev/log    local1 notice
    chroot /var/lib/haproxy
    stats socket /run/haproxy/admin.sock mode 660 level admin
    stats timeout 30s
    user haproxy
    group haproxy
    daemon

    # Default SSL material locations
    ca-base /etc/ssl/certs
    crt-base /etc/ssl/private

    # Default ciphers to use on SSL-enabled listening sockets.
    # For more information, see ciphers(1SSL). This list is from:
    #  https://hynek.me/articles/hardening-your-web-servers-ssl-ciphers/
    ssl-default-bind-ciphers ECDH+AESGCM:DH+AESGCM:ECDH+AES256::RSA+AES:RSA+3DES:!aNULL:!MD5:!DSS
    ssl-default-bind-options no-sslv3

defaults
    log    global
    mode    http
    option    httplog
    option    dontlognull
        timeout connect 5000
        timeout client  50000
        timeout server  50000
    errorfile 400 /etc/haproxy/errors/400.http
    errorfile 403 /etc/haproxy/errors/403.http
    errorfile 408 /etc/haproxy/errors/408.http
    errorfile 500 /etc/haproxy/errors/500.http
    errorfile 502 /etc/haproxy/errors/502.http
    errorfile 503 /etc/haproxy/errors/503.http
    errorfile 504 /etc/haproxy/errors/504.http

添加 HAProxy Listener, 入口流量的请求都将请求到192.168.1.12:80:

frontend Local_Server
    bind 192.168.1.12:80
    mode http
    default_backend My_Web_Servers

添加后端 Web Server, HAProxy收到的请求将转发到三个后端 Web Server:

backend nodes
    mode http
    balance roundrobin
    option forwardfor
    http-request set-header X-Forwarded-Port %[dst_port]
    http-request add-header X-Forwarded-Proto https if { ssl_fc }
    option httpchk HEAD / HTTP/1.1rnHost:localhost
    server web1.example.com  192.168.1.101:80
    server web2.example.com  192.168.1.102:80
    server web3.example.com  192.168.1.103:80

开启HAProxy的统计信息, 便于我们随时查看HAProxy的运行情况:

listen stats *:1936
    stats enable
    stats hide-version
    stats refresh 30s
    stats show-node
    stats auth username:password
    stats uri  /stats

最后完整的 /etc/haproxy/haproxy.cfg 如下:

global
    log /dev/log    local0
    log /dev/log    local1 notice
    chroot /var/lib/haproxy
    stats socket /run/haproxy/admin.sock mode 660 level admin
    stats timeout 30s
    user haproxy
    group haproxy
    daemon

    # Default SSL material locations
    ca-base /etc/ssl/certs
    crt-base /etc/ssl/private

    # Default ciphers to use on SSL-enabled listening sockets.
    # For more information, see ciphers(1SSL). This list is from:
    #  https://hynek.me/articles/hardening-your-web-servers-ssl-ciphers/
    ssl-default-bind-ciphers ECDH+AESGCM:DH+AESGCM:ECDH+AES256::RSA+AES:RSA+3DES:!aNULL:!MD5:!DSS
    ssl-default-bind-options no-sslv3

defaults
    log    global
    mode    http
    option    httplog
    option    dontlognull
        timeout connect 5000
        timeout client  50000
        timeout server  50000
    errorfile 400 /etc/haproxy/errors/400.http
    errorfile 403 /etc/haproxy/errors/403.http
    errorfile 408 /etc/haproxy/errors/408.http
    errorfile 500 /etc/haproxy/errors/500.http
    errorfile 502 /etc/haproxy/errors/502.http
    errorfile 503 /etc/haproxy/errors/503.http
    errorfile 504 /etc/haproxy/errors/504.http

frontend Local_Server
    bind 192.168.1.12:80
    mode http
    default_backend My_Web_Servers

backend My_Web_Servers
    mode http
    balance roundrobin
    option forwardfor
    http-request set-header X-Forwarded-Port %[dst_port]
    http-request add-header X-Forwarded-Proto https if { ssl_fc }
    option httpchk HEAD / HTTP/1.1rnHost:localhost
    server web1.example.com  192.168.1.101:80
    server web2.example.com  192.168.1.102:80
    server web3.example.com  192.168.1.103:80

listen stats *:1936
    stats enable
    stats hide-version
    stats refresh 30s
    stats show-node
    stats auth username:password
    stats uri  /stats

你可以通过下述命令验证配置文件的正确性:

haproxy -c -f /etc/haproxy/haproxy.cfg

让上述所有配置生效,需要重新启动 HAProxy:

systemctl restart haproxy

接下来就可以打开浏览器, 验证服务是否正常工作.因为我们的负载均衡策略是 roundrobin, 通过刷新浏览器即可看到依次访问到后端不同节点.