Docker-Slim + Flask + Gunicorn + Swagger

[myluco]

I have a project where I use gunicorn and swagger.
I can generate the image and run the server without a problem. The size of image generated is 685MB
I decided to try docker-slim. The size of image generated with docker-slim is 63.3MB . Woohoo!!!
However, when running the application using the slim image, and trying to access the ui generated by swagger, there is a problem (this problem does not happen with the "full" image).
Here is the error:

2023-01-11 01:51:45,286 - qainfra_core_service.__main__ - ERROR - Exception on /api/v1/ui/ [GET]
Traceback (most recent call last):
  File "/opt/venv/lib/python3.9/site-packages/flask/app.py", line 2447, in wsgi_app
    response = self.full_dispatch_request()
  File "/opt/venv/lib/python3.9/site-packages/flask/app.py", line 1952, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/opt/venv/lib/python3.9/site-packages/flask_cors/extension.py", line 165, in wrapped_function
    return cors_after_request(app.make_response(f(*args, **kwargs)))
  File "/opt/venv/lib/python3.9/site-packages/flask/app.py", line 1821, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/opt/venv/lib/python3.9/site-packages/flask/_compat.py", line 39, in reraise
    raise value
  File "/opt/venv/lib/python3.9/site-packages/flask/app.py", line 1950, in full_dispatch_request
    rv = self.dispatch_request()
  File "/opt/venv/lib/python3.9/site-packages/flask/app.py", line 1936, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/opt/venv/lib/python3.9/site-packages/connexion/apis/flask_api.py", line 299, in console_ui_home
    return flask.render_template('index.j2', **template_variables)
  File "/opt/venv/lib/python3.9/site-packages/flask/templating.py", line 138, in render_template
    ctx.app.jinja_env.get_or_select_template(template_name_or_list),
  File "/opt/venv/lib/python3.9/site-packages/flask/helpers.py", line 957, in __get__
    value = self.func(obj)
  File "/opt/venv/lib/python3.9/site-packages/flask/app.py", line 689, in jinja_env
    return self.create_jinja_environment()
  File "/opt/venv/lib/python3.9/site-packages/flask/app.py", line 781, in create_jinja_environment
    rv = self.jinja_environment(self, **options)
  File "/opt/venv/lib/python3.9/site-packages/flask/templating.py", line 45, in __init__
    BaseEnvironment.__init__(self, **options)
  File "/opt/venv/lib/python3.9/site-packages/jinja2/environment.py", line 359, in __init__
    self.extensions = load_extensions(self, extensions)
  File "/opt/venv/lib/python3.9/site-packages/jinja2/environment.py", line 108, in load_extensions
    extension = import_string(extension)
  File "/opt/venv/lib/python3.9/site-packages/jinja2/utils.py", line 131, in import_string
    return getattr(__import__(module, None, None, [obj]), obj)
ModuleNotFoundError: No module named 'jinja2.ext'

P.S. jinja2 and jinja2-ext are installed.
P.S.2. ENTRYPOINT and CMD instructions look like in your Dockerfile:

EXPOSE 80
CMD ["gunicorn", "-c", "./deployment/gunicorn.conf.py", "xxx_core_service.wsgi:app"]