Introduction

This tutorial aims to guide you through the process of deploying your Flask applications on three well-known platforms: AWS, Heroku, and DigitalOcean. By the end of this tutorial, you will have a clear understanding of how to take your Flask application from your local environment and deploy it on these platforms.

Prerequisites:
- Basic Knowledge of Python
- Familiarity with Flask
- Accounts on AWS, Heroku, and DigitalOcean

Step-by-Step Guide

Deploying Flask on AWS (Elastic Beanstalk)

1. Install the AWS CLI and EB CLI.
2. Initialize your EB CLI repository with eb init -p python-3.6 my-flask-app in your project's root folder.
3. Create the environment with eb create my-flask-env.
4. Navigate to the AWS Elastic Beanstalk console to view the newly created environment.
5. To deploy, use eb deploy.

Deploying Flask on Heroku

1. Install the Heroku CLI.
2. Log in to your Heroku account with heroku login.
3. Navigate to the root folder of your project and initialize a git repository with git init.
4. Create a new Heroku app with heroku create.
5. Add all your changes to git, then commit with git add . and git commit -m "Deploy".
6. Push your commit to Heroku with git push heroku master.

Deploying Flask on DigitalOcean

1. Create a new droplet on DigitalOcean.
2. Log in to your droplet via SSH.
3. Update the package list with sudo apt-get update.
4. Install Python, pip, and nginx with sudo apt-get install python3-pip python3-dev nginx.
5. Clone your Flask project into your droplet.
6. Install your project's dependencies with pip.
7. Configure Nginx to forward requests to your Flask application.
8. Use gunicorn to serve your application.

Code Examples

Example for AWS

# application.py

from flask import Flask
application = Flask(__name__)

@application.route("/")
def hello():
    return "Hello AWS!"

if __name__ == "__main__":
    application.run(host='0.0.0.0', port=80)

Example for Heroku

# app.py

from flask import Flask
app = Flask(__name__)

@app.route("/")
def hello():
    return "Hello Heroku!"

if __name__ == "__main__":
    app.run()

Example for DigitalOcean

# main.py

from flask import Flask
app = Flask(__name__)

@app.route("/")
def hello():
    return "Hello DigitalOcean!"

if __name__ == "__main__":
    app.run(host='0.0.0.0', port=80)

Summary

We covered how to deploy a Flask application on AWS, Heroku, and DigitalOcean. We learned how to use the AWS CLI, EB CLI, Heroku CLI, Git, and Nginx.

For further learning:
- Explore AWS, Heroku, and DigitalOcean documentation.
- Learn about Docker for creating containers for your applications.

Practice Exercises

1. Create a basic Flask application and deploy it on Heroku.
2. Deploy the same Flask application on AWS.
3. Explore how to use a database in your Flask application and deploy it on DigitalOcean.

Solutions:
1. Follow the steps from the "Deploying Flask on Heroku" section.
2. Follow the steps from the "Deploying Flask on AWS" section.
3. Add a database to your Flask app using SQLAlchemy and follow the steps from the "Deploying Flask on DigitalOcean" section.

Remember to practice and explore further to strengthen your understanding and skills.