Hello Flask

This is a tutorial how to build a simple web app with Python on your local machine.

We’ll use a micro-framework called Flask.

Flask is based on the Werkzeug WSGI toolkit and and Jinja2 template engine.

Prerequisites

• Install Python 3
• Update pip to newest version: python -m pip install --upgrade pip
• Install pipenv (virtual environment): pip install pipenv

Run Flask app

• Create project directory: mkdir hello-flask
• Go to project directory: cd hello-flask
• Inside project directory create a web app index.py

  from flask import Flask
  app = Flask(__name__)
  @app.route('/')
  def home():
      return '<h1>Hello Flask!<h1>'

• Create virtual environment and install dependencies: pipenv install
• Install Flask into virtual environment: pipenv install flask
• Open pipenv shell: pipenv shell
• Define which app to run: export FLASK_APP=index.py
• Run the app: flask run
• Open the app in web browser: http://127.0.0.1:5000