deploy_flask_app.txt

# login to heroku
heroku login

# init empty repo
git init

# create app
heroku create your-first-heroku-app --buildpack heroku/python

# add remote git
heroku git:remote -a your-first-heroku-app

# requirements.txt with gunicorn server in it is needed to work
# create "Procfile" in the project root containing
web: gunicorn app:app    // app.py/app instance name

# commit changes
git add .
git commit -m "First commit for heroku"
git push heroku master