Bug#453630: apache2: Major host parsing error in <Proxy balancer:/..> section

From: Benoit Plessis <benoit(at)plessis.info>
Date: Thu Nov 29 2007 - 14:54:05 EST

Package: apache2
Version: 2.2.3-4+etch1
Severity: important

Hi,
I encoutered a weird error using mod_proxy_balancer and multiple <Proxy balancer://> section.

Here is the config file:
---8<--------------------------------------------------------------------------
<Proxy balancer://back1>

       BalancerMember  
http://1.1.1.1
       BalancerMember  
http://1.1.1.3

</Proxy>
<Proxy balancer://back2>

       BalancerMember  
http://1.1.1.10
       BalancerMember  
http://1.1.1.11
       BalancerMember  
http://1.2.1.11
       BalancerMember  
http://1.1.1.31

</Proxy>
---8<--------------------------------------------------------------------------

Here is the output of balancer-manager via html2text:
---8<--------------------------------------------------------------------------

• Load Balancer Manager for bd7 ****** Server Version: Apache/2.2.3 (Debian) Server Built: Jun 17 2007 20:16:04

  ---

  • LoadBalancer Status for balancer://back1 **** StickySession Timeout FailoverAttempts Method 0 2 byrequests

Worker URL     Route RouteRedir Factor Status
http://1.1.1.1                  1      Ok
http://1.1.1.3                  1      Ok
===============================================================================

**** LoadBalancer Status for balancer://back2 **** StickySession Timeout FailoverAttempts Method

              0       3                byrequests

Worker URL      Route RouteRedir Factor Status
http://1.1.1.1                   1      Ok
http://1.1.1.1                   1      Ok
http://1.2.1.11                  1      Ok
http://1.1.1.3                   1      Ok
===============================================================================
     Apache/2.2.3 (Debian) Server at bd7 Port 80

---8<--------------------------------------------------------------------------

Like you could see, there an abnormal shrink of the Worker URL in the second balancer status. It's kinda like when parsing the config file worker addresses are compared to previous worker but using the length() of the previous workers

And the traffic isn't sent to the configured Urls. One way to workaround is reverse the definition of the balancer:
---8<--------------------------------------------------------------------------
<Proxy balancer://back2>

       BalancerMember  
http://1.1.1.10
       BalancerMember  
http://1.1.1.11
       BalancerMember  
http://1.2.1.11
       BalancerMember  
http://1.1.1.31

</Proxy>
<Proxy balancer://back1>

       BalancerMember  
http://1.1.1.1
       BalancerMember  
http://1.1.1.3

</Proxy>
---8<--------------------------------------------------------------------------

But i fear that there is more implication than just this and than this could affect the entire mod_proxy module, since i've some weird result just using mod_rewrite and mod_proxy with same kind of destination URLs and traffic that flow where it shouldn't.

Regards,
benoit

• System Information: Debian Release: lenny/sid APT prefers unstable APT policy: (500, 'unstable'), (1, 'experimental') Architecture: i386 (i686)

Kernel: Linux 2.6.22-3-686 (SMP w/2 CPU cores) Locale: LANG=fr_FR.UTF-8, LC_CTYPE=fr_FR.UTF-8 (charmap=UTF-8) Shell: /bin/sh linked to /bin/bash

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Received on Fri Nov 30 05:04:58 2007