I have such trouble. There are nginx (as frontent to apache) and apache with mod_rpaf installed. It worked good for a month or so. But today error 502 returned to some requests to php (not all requests cause this error). And it's a great mistery)), 'cause nothing was removed, nothing was installed\upgraded.
Some investigation cleared that:
this doesn't depend on heaviness of request - error returned in less then a second (so it's not timeout).
removing of mod_rpaf cleares the problem
Are there any ways to workaround this issue or maybe could you guess me some alternative to mod_rpaf.
Thanks in advance!
actually error was caused with big size of
firephp headers, so in some way it caused
mod_rpaf to fail. resolved by reducing headers size and disabling
mod_rpaf (thanks to @coredump) now I have client IP adress in