Installation of pylons (ckan) Mod_wsgi does not work

Question

I install CKAN, the pylon application according to these instructions: http://packages.python.org/ckan/deployment.html

But when I point to the server (DNS is not yet configured) using IP or hostname, I see only the apache welcome page, and the ckan application does not load.

here is my mod_wsgi script:

import os instance_dir = '/home/flavio/var/srvc/ckan.emap.fgv.br' config_file = 'ckan.emap.fgv.br.ini' pyenv_bin_dir = os.path.join(instance_dir, 'pyenv', 'bin') activate_this = os.path.join(pyenv_bin_dir, 'activate_this.py') execfile(activate_this, dict(__file__=activate_this)) from paste.deploy import loadapp config_filepath = os.path.join(instance_dir, config_file) from paste.script.util.logging_config import fileConfig fileConfig(config_filepath) application = loadapp('config:%s' % config_filepath) 

here is my virtual host configuration:

 <VirtualHost *:80> ServerName dck093 ServerAlias dck093 WSGIScriptAlias / /home/flavio/var/srvc/ckan.emap.fgv.br/pyenv/bin/ckan.emap.fgv.br.py # pass authorization info on (needed for rest api) WSGIPassAuthorization On ErrorLog /var/log/apache2/ckan.emap.fgv.br.error.log CustomLog /var/log/apache2/ckan.emap.fgv.br.custom.log combined <Directory /home/flavio/var/srvc/ckan.emap.fgv.br/pyenv/bin> Order deny,allow Allow from all </Directory> </VirtualHost> 

I am trying to disable the 000-default site (with a2dissite), but that will not help. After that, I get a page with an internal server error. After fixing some permissions, I managed to get this Pylons error log:

 sudo tail /var/log/apache2/ckan.emap.fgv.br.error.log [Wed Mar 30 12:38:32 2011] [error] [client 10.250.48.110] app_iter = self.application(environ, start_response) [Wed Mar 30 12:38:32 2011] [error] [client 10.250.48.110] File "/usr/lib/pymodules/python2.6/repoze/who/middleware.py", line 107, in __call__ [Wed Mar 30 12:38:32 2011] [error] [client 10.250.48.110] app_iter = app(environ, wrapper.wrap_start_response) [Wed Mar 30 12:38:32 2011] [error] [client 10.250.48.110] File "/home/flavio/var/srvc/ckan.emap.fgv.br/pyenv/lib/python2.6/site-packages/pylons/middleware.py", line 201, in __call__ [Wed Mar 30 12:38:32 2011] [error] [client 10.250.48.110] self.app, environ, catch_exc_info=True) [Wed Mar 30 12:38:32 2011] [error] [client 10.250.48.110] File "/home/flavio/var/srvc/ckan.emap.fgv.br/pyenv/lib/python2.6/site-packages/pylons/util.py", line 94, in call_wsgi_application [Wed Mar 30 12:38:32 2011] [error] [client 10.250.48.110] app_iter = application(environ, start_response) [Wed Mar 30 12:38:32 2011] [error] [client 10.250.48.110] File "/usr/lib/pymodules/python2.6/weberror/evalexception.py", line 226, in __call__ [Wed Mar 30 12:38:32 2011] [error] [client 10.250.48.110] "The EvalException middleware is not usable in a " [Wed Mar 30 12:38:32 2011] [error] [client 10.250.48.110] AssertionError: The EvalException middleware is not usable in a multi-process environment 

Can anyone point out what I am missing?

Answer 1

Since you are deploying to apache, make sure you are not in interactive debugging mode that uses an EvalException. In your Pylons configuration file (ckan.emap.fgv.br.ini), make sure you have this:

 [app:main] set debug = false 

Answer 2

Your first problem is that you cannot use name-based virtual hosts in Apache without a host name in DNS or local / etc / hosts, which resolves the IP address of the Apache server.

The second problem is that an EvalException cannot be used in a multiprocessor server configuration. Read:

http://code.google.com/p/modwsgi/wiki/DebuggingTechniques#Browser_Based_Debugger

Either throw an EvalException or configure mod_wsgi so that you use the daemon mode with "default" for a single process (do not use processes = 1).

For the background for the various process / thread configurations available for Apache / mod_wsgi, read:

http://code.google.com/p/modwsgi/wiki/ProcessesAndThreading

You want to use the one where wsgi.multiprocess is False.

Answer 3

Not an expert in the "paste" environment, but should not be:

 from paste.deploy.loadwsgi import loadapp 

Answer 4

I agree that debugging should be disabled during production, but I would really like to see stacktraces of exceptions.

Right now, if I get 500 server errors inside CKAN (a good CKAN page with error information is displayed) in the logs, I can only find the error description without stacktrace:

[Thu Feb 12 17:04:55.037785 2015] [:error] [pid 15293:tid 139979468994304] [remote 89.71.231.138:5513] Error - <type 'exceptions.TypeError'>: 'NoneType' object is not iterable

Is there a way to enable full stacktrace with debug = false.