Creating Flask App and deploying it in Heroku

Live Demo - https://flaskdemobasic.herokuapp.com

Create a Flask App

1. Create a virtual environment

   • In Windows

   virtualenv env
   cd env\Scripts
   .\activate

   • In Linux/Mac

   virtualenv env
   source env/bin/activate

2. Install Flask Module

   pip install Flask --upgrade

3. Create a .gitignore file and add the following lines

   __pycache__/
   *.py[cod]
   .vscode
   env/
   

4. Sample Flask app which returns current Date

   from flask import Flask
   from datetime import datetime
   app = Flask(__name__)
   
   @app.route('/')
   def func():
       return str(datetime.now())
   
   if __name__ == '__main__':
       app.run()

5. Run the app

   python app.py

   When you goto http://localhost:5000/ you should be able to see current date and time.

Deploying this app in Heroku

1. Create a new file and name it as Procfile in the project's root folder and add the following text

   web: gunicorn app:app
   

2. Add guicorn module and other installed modules to requirements.txt

   pip install gunicorn --upgrade
   pip freeze > requirements.txt

3. Specify a python runtime. Example: python-3.6.2

   • Create a file called runtime.txt in the project's root folder and add the following text

   python-3.6.2
   

4. Create a heroku app

   heroku create flaskdemoapp

5. Initialize git and add remote as heroku

   git init
   git remote add prod git@heroku.com:flaskdemoapp.git

6. Commit and push

   git add .
   git commit -m "Your message"
   git push -u prod master

7. Incase if you had not added public key, then

   heroku login #Username & Password
   heroku keys:add ~/.ssh/id_rsa.pub