Openshift + HAproxy 503 custom page

haproxyhttp-status-codeopenshift-online-2

I'm using 503 HTTP Status and a coming soon page for maintenance mode.

Is there any way to get HAproxy serving server-side generated 503 page instead of the default blank/unavailable page?

I'm using Openshift + HAproxy + Cloudflare + PHP.

Thanks in advance.

Haproxy config (some comments removed):

#---------------------------------------------------------------------
# Global settings
#---------------------------------------------------------------------
global
    log         127.0.0.1 local2

    chroot      /var/lib/haproxy
    pidfile     /var/run/haproxy.pid
    maxconn     4000
    user        haproxy
    group       haproxy
    daemon

    # turn on stats unix socket
    stats socket /var/lib/haproxy/stats

#---------------------------------------------------------------------
# common defaults that all the 'listen' and 'backend' sections will
# use if not designated in their block
#---------------------------------------------------------------------
defaults
    mode                    http
    log                     global
    option                  httplog
    option                  dontlognull
    option http-server-close
    option forwardfor       except 127.0.0.0/8
    option                  redispatch
    retries                 3
    timeout http-request    10s
    timeout queue           1m
    timeout connect         10s
    timeout client          1m
    timeout server          1m
    timeout http-keep-alive 10s
    timeout check           10s
    maxconn                 3000

#---------------------------------------------------------------------
# main frontend which proxys to the backends
#---------------------------------------------------------------------
frontend  main *:5000
    acl url_static       path_beg       -i /static /images /javascript /stylesheets
    acl url_static       path_end       -i .jpg .gif .png .css .js

    use_backend static          if url_static
    default_backend             app

#---------------------------------------------------------------------
# static backend for serving up images, stylesheets and such
#---------------------------------------------------------------------
backend static
    balance     roundrobin
    server      static 127.0.0.1:4331 check

#---------------------------------------------------------------------
# round robin balancing between the various backends
#---------------------------------------------------------------------
backend app
    balance     roundrobin
    server  app1 127.0.0.1:5001 check
    server  app2 127.0.0.1:5002 check
    server  app3 127.0.0.1:5003 check
    server  app4 127.0.0.1:5004 check

Best Answer

Is there any way to get HAproxy serving server-side generated 503 page instead of the default blank/unavailable page?

This isn't the actual question you should be asking. HAProxy always uses the server's response. The error file is only used for errors generated internally by HAProxy.

If you check your web server logs, you'll find that these specific requests are not actually being sent to the web server.

This is happening because HAProxy thinks your server is down... because it's getting 503 from the server in response to the health check.

If the server were returning 502 or 400 or any error code on the health checks, you'd still receive the 503 from HAProxg because the server is, officially, down.

WARNING] 201/142518 (192371) : Server express/local-gear is DOWN, reason: Layer7 wrong status, code: 503, info: "HTTP status check returned code <3C>503<3E>", check duration: 87ms. 0 active and 0 backup servers left. 0 sessions active, 0 requeued, 0 remaining in queue

You have apparently redacted the line option httpchk from the configuration you posted, but it has to be there, or HAProxy would only do a layer 4 check, and this wouldn't be happening.

The simplest solution is to remove that line from the backend or default config.

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