Life Expectancy Prediction Model using Flask and Heroku

Using ML model to predict Life Expectancy for each country and how to deploy a Python Flask application to Heroku.

3 options for running the project:

1. Local run for testing - run as a python file server.py without Gunicorn locally. Since environment variable 'PORT' does not exist, will listen on default Flask port 5000 on localhost only.
2. Heroku without Gunicorn - run as a python file server.py without Gunicorn on Heroku. Use the following line in Procfile: web: python server.py. Will listen on port given by Heroku in environment variable PORT
3. Heroku with Gunicorn - change Procfile file to: web: gunicorn server:app. Then Gunicorn will run inside Heroku dyno with multiple instances of the server.py specified by Heroku in environment variable WEB_CONCURRENCY depending on available and used memory in the dyno.