ModuleNotFoundError in gunicorn start

Question

My Django project has this directory structure:

.
├── gnjp
│   ├── gnjp
│   │   ├── settings.py
│   │   ├── urls.py
│   │   └── wsgi.py
│   ├── app1
│   ├── app2
│   ├── manage.py
│   └── templates
├── bin
├── include
├── lib

using a virtual environment and works fine with python manage.py runserver using some pip-installed modules like django-bootstrap4, django-bootstrap-datepicker-plus.

From the higher-level gnjp-directory I do gunicorn gnjp.wsgi and get this error:

[2019-09-07 14:20:28 +0200] [72408] [INFO] Starting gunicorn 19.9.0
[2019-09-07 14:20:28 +0200] [72408] [INFO] Listening at: http://127.0.0.1:8000 (72408)
[2019-09-07 14:20:28 +0200] [72408] [INFO] Using worker: sync
[2019-09-07 14:20:28 +0200] [72411] [INFO] Booting worker with pid: 72411
[2019-09-07 14:20:28 +0200] [72411] [ERROR] Exception in worker process
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/site-packages/gunicorn/arbiter.py", line 583, in spawn_worker
    worker.init_process()
  File "/usr/local/lib/python3.7/site-packages/gunicorn/workers/base.py", line 129, in init_process
    self.load_wsgi()
  File "/usr/local/lib/python3.7/site-packages/gunicorn/workers/base.py", line 138, in load_wsgi
    self.wsgi = self.app.wsgi()
  File "/usr/local/lib/python3.7/site-packages/gunicorn/app/base.py", line 67, in wsgi
    self.callable = self.load()
  File "/usr/local/lib/python3.7/site-packages/gunicorn/app/wsgiapp.py", line 52, in load
    return self.load_wsgiapp()
  File "/usr/local/lib/python3.7/site-packages/gunicorn/app/wsgiapp.py", line 41, in load_wsgiapp
    return util.import_app(self.app_uri)
  File "/usr/local/lib/python3.7/site-packages/gunicorn/util.py", line 350, in import_app
    __import__(module)
  File "/..../gnjp/gnjp/wsgi.py", line 16, in <module>
    application = get_wsgi_application()
  File "/usr/local/lib/python3.7/site-packages/django/core/wsgi.py", line 12, in get_wsgi_application
    django.setup(set_prefix=False)
  File "/usr/local/lib/python3.7/site-packages/django/__init__.py", line 24, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/usr/local/lib/python3.7/site-packages/django/apps/registry.py", line 91, in populate
    app_config = AppConfig.create(entry)
  File "/usr/local/lib/python3.7/site-packages/django/apps/config.py", line 90, in create
    module = import_module(entry)
  File "/usr/local/Cellar/python/3.7.4/Frameworks/Python.framework/Versions/3.7/lib/python3.7/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
ModuleNotFoundError: No module named 'bootstrap_datepicker_plus'
[2019-09-07 14:20:28 +0200] [72411] [INFO] Worker exiting (pid: 72411)
[2019-09-07 14:20:28 +0200] [72408] [INFO] Shutting down: Master
[2019-09-07 14:20:28 +0200] [72408] [INFO] Reason: Worker failed to boot.

I can see the bootstrap-datepicker-plus in site-packages in the virtual environment.

Some parts of my settings.py that might be relevant:

INSTALLED_APPS = [
  'app1',
  'app2'
  'bootstrap4',
  'bootstrap_datepicker_plus'
]
WSGI_APPLICATION = 'gnjp.wsgi.application'

My gnjp/wsgi.py has this content:

import os
from django.core.wsgi import get_wsgi_application
os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'gnjp.settings')
application = get_wsgi_application()

Answer 1

Try adding this at the start of your wsgi file:

python_home='/path/to/your/venv'
activate_this=python_home+'/bin/activate_this.py'
with open(activate_this) as file_:
        exec(file_.read(), dict(__file__=activate_this))

assuming that you created your virtual environment using virtualenv