HAProxy, health checking multiple servers with different host names

Posted by Marco Bettiolo on Server Fault See other posts from Server Fault or by Marco Bettiolo
Published on 2014-05-13T01:38:13Z Indexed on 2014/05/28 21:34 UTC
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I need to load balance between multiple running servers with different host names. I cannot set-up the same virtual host on each one.

Is it possible to have only one listen configuration with multiple server and make the Health Checks apply the http-send-name-header Host directive? I am using HAProxy 1.5.

I came up with this working haproxy.cfg, as you can see, I had to set a different hostname for each health check as the health check ignores the http-send-name-header Host. I would have preferred to use variables or other methods and keep things more concise.

global
    log 127.0.0.1 local0 notice
    maxconn 2000
    user haproxy
    group haproxy

defaults
    log     global
    mode    http
    option  httplog
    option  dontlognull
    retries 3
    option redispatch
    timeout connect  5000
    timeout client  10000
    timeout server  10000
    stats enable
    stats uri /haproxy?stats
    stats refresh 5s
    balance roundrobin
    option httpclose

listen inbound :80    
    option httpchk HEAD / HTTP/1.1\r\n
    server instance1 127.0.0.101 check inter 3000 fall 1 rise 1
    server instance2 127.0.0.102 check inter 3000 fall 1 rise 1

listen instance1 127.0.0.101:80
    option forwardfor
    http-send-name-header Host
    option httpchk HEAD / HTTP/1.1\r\nHost:\ www.example.com
    server www.example.com www.example.com:80 check inter 5000 fall 3 rise 2

listen instance2 127.0.0.102:80
    option forwardfor
    http-send-name-header Host
    option httpchk HEAD / HTTP/1.1\r\nHost:\ www.bing.com
    server www.bing.com www.bing.com:80 check inter 5000 fall 3 rise 2

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