Troubleshooting Dreamhost + Passenger + Django

[Rob Newman]

Hi there,

I posted a message on Stack Overflow about this already (http://stackoverflow.com/questions/23725107), and I am turning to this mailing list for additional help. It seems that Passenger is ignoring the version of Python I have installed in a virtualenv. I followed the instructions of Dreamhost to the letter (http://wiki.dreamhost.com/Passenger#Passenger_WSGI_and_virtualenv) but I am still getting the following error in my application:

An error occurred while starting the web application. It exited before signalling successful startup back to Phusion Passenger. Please read this article for more information about this problem.

Raw process output:

  File "/dh/nginx/passenger/helper-scripts/wsgi-loader.py", line 171
    buf = b''
            ^
SyntaxError: invalid syntax

Here is the content of my passenger_wsgi.py file:

import sys, os
INTERP = "/home/<user>/venv/tcs/bin/python2.6"
if sys.executable != INTERP: os.execl(INTERP, INTERP, *sys.argv)
# print(sys.version)
sys.path.append(os.getcwd())
sys.path.append(os.path.join(os.getcwd(), '/home/<user>/<application>/<dir>'))
os.environ['DJANGO_SETTINGS_MODULE'] = "project.settings"
import django.core.handlers.wsgi
application = django.core.handlers.wsgi.WSGIHandler()

(<user>, <application> and <dir> hidden for obvious reasons)

When I uncomment the print(sys.version) I get the following output:

2.6.8 (unknown, Jul 10 2012, 08:03:16)
[GCC 4.3.2]

So I know that this version of Python is apparently supported:
http://www.modrails.com/documentation/Users%20guide%20Nginx.html#_supported_operating_systems_and_languages

Any ideas? I have already sent multiple support requests to Dreamhost, which are currently unanswered.

Thanks in advance,
- Rob Newman

[Hongli Lai]

The Dreamhost instructions are outdated. In those instructions, the
app checks whether it is running under the correct Python interpreter,
and if not, re-executes itself under the correct Python interpreter.
However, before Phusion Passenger ever loads your app, it first runs a
"loader" application which sets up the environment for your app. And
it is that loader application that requires Python >= 2.6. So the
re-execution trick only works properly if the Python that was used to
run the loader, is >= 2.6. At Dreamhost, that's apparently not the
case.

The correct way to run your app under a different Python is not by
re-executing itself, but by using the PassengerPython configuration
option inside the web server:
http://www.modrails.com/documentation/Users%20guide%20Apache.html#_passengerpython_lt_filename_gt
If Dreamhost gives you access to the Apache config file, you can set
it there directly. If they don't, then you *might* still be able to
customize it through .htaccess, assuming that Dreamhost gave you
access to do this through 'AllowOverride on'.

Otherwise, you might want to consider switching provider.

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[Hongli Lai]

I see the web server is Nginx, not Apache. However the conclusion
remains the same: use the passenger_python option:
http://www.modrails.com/documentation/Users%20guide%20Nginx.html#_passenger_python_lt_filename_gt

[Rob Newman]

Thanks Hongli Lai! I will test that out tonight!! Much appreciated.

[Rob Newman]

Hi Hongli Lai,

This fixed it - thank you!!!!

On Tuesday, May 20, 2014 1:42:19 AM UTC-7, Hongli Lai wrote: