Re: RE: mod_proxy issue - intermittent 502 response

[Tom Evans <tevans.uk@xxxxxxxxxxxxxx>]

On Fri, Nov 27, 2009 at 9:52 AM, Cristian Pini <cris.pini@xxxxxxxxx> wrote:

Thx for taking the time to read the post.

You're right in that it's difficult to determine whether Apache is the problem, however, there's nothing sitting between the proxy and the app server and the only things that are running on the app server are apache (mod_perl) and sendmail.

Having reviewed the access and error log on the proxy I can see an entry for a request that subsequently fails, however, neither the access or error logs on the app server have an entry for the request. This suggests that the request is never reaching the app server but as there's only one hop between them I'm struggling to understand what is happening to the request from the proxy.

Rgds,

Cris

The 502 error basically says that the proxy couldn't connect to the backend or that the backend responded with something that it couldn't understand. Examine your network, your backend app and tcpdump the entire exchange. It is unlikely to have much to do with the proxy, which is why googling for a solution to your proxy errors did not return anything of note - this is almost always either the backend not coping, or the network not coping.

Cheers

Tom