Expose Flask (connexion) instance to Uwsgi in Nginx

When running my Docker image and requesting the Swagger Ui I receive: 502 Bad Gateway.

I am attempting to run connexion (Flask-based Swagger UI generator) with UWSGI on NGINX. I assume it is because Uwsgi does not correctly pick up my Flask instance. However, it appears to me that my container instance is correctly configured.

If you look here https://github.com/Microsoft/python-sample-vscode-flask-tutorial, the setup of my application and the configuration is similar and it works without issues.

According to the connexion documentation I should be able to expose the app instance to uWSGI using

app = connexion.App(__name__, specification_dir='swagger/')
application = app.app # expose global WSGI application object

You can find my complete application code here:

https://bitbucket.org/lammy123/flask_nginx_docker_connexion/src/master/

The Flask/Connexion object is in application/__init__.py

uwsgi.ini:

[uwsgi]
module = application.webapp
callable = app
uid = 1000
master = true
threads = 2
processes = 4

__init__.py:

import connexion

app = connexion.App(__name__, specification_dir='openapi/')
app.add_api('helloworld-api.yaml', arguments={'title': 'Hello World Example'})

webapp.py:

from . import app    # For application discovery by the 'flask' command. 
from . import views  # For import side-effects of setting up routes.
from . import app
import connexion

application = app.app

Running the code with the build-in development server works.

Expected behavior is that the Swagger UI is available at:

http://localhost:5000/v1.0/ui/#/

when running from a Docker container.

Thank you for your time.

Source: StackOverflow