Unable to make gunicorn run on EC2 - django

Question

I am following this tutorial to setup a Django-gunicorn-nginx server in AWS EC2. After installing all dependancies and making a change in wsgi.py as follows
import os, sys
# add the hellodjango project path into the sys.path
sys.path.append('/home/ubuntu/project/ToDo-application/')
# add the virtualenv site-packages path to the sys.path
sys.path.append('/home/ubuntu/.local/lib/python3.6/site-packages')
# poiting to the project settings
os.environ.setdefault("DJANGO_SETTINGS_MODULE", "todo_app.settings")
from django.core.wsgi import get_wsgi_application
application = get_wsgi_application()
I run gunicorn todo_app.wsgi and get the following error:
ubuntu#ip-172-31-61-163:~/project/ToDo-application$ gunicorn todo_app.wsgi
[2018-11-07 11:25:35 +0000] [8211] [INFO] Starting gunicorn 19.7.1
[2018-11-07 11:25:35 +0000] [8211] [INFO] Listening at: http://127.0.0.1:8000 (8211)
[2018-11-07 11:25:35 +0000] [8211] [INFO] Using worker: sync
[2018-11-07 11:25:35 +0000] [8215] [INFO] Booting worker with pid: 8215
[2018-11-07 11:25:35 +0000] [8215] [ERROR] Exception in worker process
Traceback (most recent call last):
File "/usr/lib/python2.7/dist-packages/gunicorn/arbiter.py", line 578, in spawn_worker
worker.init_process()
File "/usr/lib/python2.7/dist-packages/gunicorn/workers/base.py", line 126, in init_process
self.load_wsgi()
File "/usr/lib/python2.7/dist-packages/gunicorn/workers/base.py", line 135, in load_wsgi
self.wsgi = self.app.wsgi()
File "/usr/lib/python2.7/dist-packages/gunicorn/app/base.py", line 67, in wsgi
self.callable = self.load()
File "/usr/lib/python2.7/dist-packages/gunicorn/app/wsgiapp.py", line 65, in load
return self.load_wsgiapp()
File "/usr/lib/python2.7/dist-packages/gunicorn/app/wsgiapp.py", line 52, in load_wsgiapp
return util.import_app(self.app_uri)
File "/usr/lib/python2.7/dist-packages/gunicorn/util.py", line 377, in import_app
__import__(module)
File "/home/ubuntu/urbanpiper/ToDo-application/todo_app/wsgi.py", line 20, in <module>
from django.core.wsgi import get_wsgi_application
File "/home/ubuntu/.local/lib/python3.6/site-packages/django/__init__.py", line 1, in <module>
from django.utils.version import get_version
File "/home/ubuntu/.local/lib/python3.6/site-packages/django/utils/version.py", line 71, in <module>
#functools.lru_cache()
AttributeError: 'module' object has no attribute 'lru_cache'
Is this because of gunicorn having python2 dependancies and Django being on python3? I tried uninstalling gunicorn and trying it again but it did not work.

Answer 1

# WRONG:
# add the virtualenv site-packages path to the sys.path
sys.path.append('/home/ubuntu/.local/lib/python3.6/site-packages')
You ought to create a virutalenv for each uwsgi application you wish to host on the server, rather than setting the virtualenv to the path above. If you followed the linked tutorial word-by-word, then this is the part which needs more explaining:
Make a virtualenv and install your pip requirements
Essentially:
# install virtualenv3
sudo apt-get install virtualenv3
# create the virtual environment, specifically for the stated python version
virtualenv -p python3.6 TITLE_OF_VENV
# You now have a directory called TITLE_OF_VENV (You may wish to replace this
# with something more subtle).
# Activate the virtualenv for your current shell session
. TITLE_OF_VENV/bin/activate
# The dot above is intentional and is a quick way to write source, which
# imports the environment vars
Your shell prompt should now look like this: (TITLE_OF_VENV) ubuntu#ip-172-31-61-163:~/project/ToDo-application$ indicating that the venv is active. To switch out of the venv run the command deactivate.
Anything which you install with pip here will then live in the directory TITLE_OF_VENV/python3.6/site-packages (while this virutal environment is active). This has the advantage of keeping different project requirements separate.
Test the python version (with the venv still active):
(TITLE_OF_VENV)$ python --version
Python 3.6
Now install gunicorn into this virtual environment, along with any other project requirements:
(TITLE_OF_VENV)$ pip install gunicorn
(TITLE_OF_VENV)$ pip install -r requirements.txt
Update your uwsgi.py:
import os
# poiting to the project settings
os.environ.setdefault("DJANGO_SETTINGS_MODULE", "todo_app.settings")
from django.core.wsgi import get_wsgi_application
application = get_wsgi_application()
And then launch it from within the virtual environment:
(TITLE_OF_VENV)$ gunicorn todo_app.wsgi:application
You could add the -D flag to the gunicorn command also, which makes it run in the background. Also don't make this server publicly accessible. If it's a production box, you need to run it behind nginx!