SetEnv PYTHON_EGG_CACHE fails with TracEnvParentDir

[hollow@…]

If multiple trac environments are used together with TracEnvParentDir, the changes introduced in r7440 in modpython_frontend.py fail to pick up the SetEnv option for PYTHON_EGG_CACHE, since TracEnvParentDir is checked first to build a default path. If one wants to use the implicit cache path in TracEnvParentDir trac fails too, since the cache is not a trac environment.

Example config:

SetHandler mod_python
PythonHandler trac.web.modpython_frontend
PythonOption TracEnvParentDir /var/lib/trac
PythonOption TracUriRoot /trac
SetEnv PYTHON_EGG_CACHE /var/www/localhost/egg_cache/

The workaround is to use PythonOption PYTHON_EGG_CACHE, but then the ENV code is useless. So either way, the logic has to be cleaned up :)

[Christian Boos]

Probably, yes.

[osimons]

That's a limitation of embedded mod_python - the process has initialized itself with OS variables from Apache launch, but mod_python can/will never use SetEnv and PassEnv directives - they have no effect. So, for anything mod_python, PythonOption needs to be used.

There isn't anything the Trac project can do about that, and I think at least the TracModPython documentation uses PythonOption for all request-settings.

'worksforme'?

[Christian Boos]

Hm, are you sure SetEnv doesn't use putenv?

[Christian Boos]

Ok, it doesn't look like.

So worksforme: use PythonOption.

What about the SetEnv HTTPS 1 from TracModPython#HTTPSissues, is that also wrong?

[osimons]

No, that's right - but it shows up in req.environ and we read it from there as a per-request option. Which if fine. I should probably be more specific, as what I meant was that any SetEnv will not affect mod_python itself, and the environment mod_python use to initialize itself and its package loading and so on - the os.environ mod_python uses must be set before Apache starts, and not part of httpd.conf.