Possible bug - request forwarding to wrong backend

Hi,

I have been struggling with this bug for a little while and wanted to report it and see if you can either help me or fix this bug. Here is a sample config file which shows the bug

*global*

• log 127.0.0.1 local0*
• user nobody*
• group nogroup*
• daemon*
• pidfile /var/run/haproxy.pid*
  *
  *
  *defaults*
  
• log global*
• mode http*
• option httplog*
  *
  *
  
• timeout client 10s*
• timeout connect 5s*
• timeout http-request 10s*
• timeout server 60s*
  *
  *
  *frontend http*
  
• bind 0.0.0.0:80 <http://0.0.0.0/>*
• acl path_group_a path_beg /login /logout /admin /secure /js/ /css/*
• *
• user_backend back_a if path_group_a*
• default_backend back_b*
• *
  *backend back_a*
  
• server a1 10.20.203.165:80 <http://10.20.203.165/>*
  *backend back_b*
  
• server b1 10.20.122.68:80 <http://10.20.122.68/>*
  *
  *
  *
  *
  Basically, the config is just distributing http connections between 2 servers based on the path. However, I am constantly seeing haproxy sending traffic to the wrong backend. The backend back_b in the example above is responsible for all pages except a few like /login, /logout, /admin, /secure etc.

The bug can be reproduced by
a) User goes to home page. Haproxy forwards the request to back_b. b) User clicks the login link (/login which is supposed to be sent to back_a).
c) User receives response from back_b instead of back_a

If the user clicks on a link quickly the request ends up going to back_b instead of back_a as expected based on ACL. Moreover, haproxy doesn't log the request and its routing to back_b. Whenever haproxy logs the request, it is sending to the right backend. The wrong backend logs do show them receiving requests from ip running haproxy. So, it has to be haproxy forwarding those requests.

I have tried running haproxy in debug mode too but am unable to see the requests there too. Somehow the request is getting routed to wrong backend and there is no log generated for that bug in info mode or debug mode.

Please help ! I am trying to set up a production infrastructure and solving this problem would be a great help.

Thanks,
Vivek
310-754-5861 Received on 2011/04/04 11:21