Phase 9 - Deployment

Deployment is where many Flask apps break because development and production environments behave differently.

This phase teaches a practical deployment mental model:

• your Flask app is a WSGI app
• Gunicorn runs it with multiple workers
• Nginx sits in front as a reverse proxy
• configuration comes from environment variables

You’ll learn

• Preparing for production
• Environment variables and .env
• Gunicorn
• Nginx as reverse proxy
• Dockerizing a Flask app
• Deploying to Render
• Deploying to PythonAnywhere
• Deploying to AWS EC2

Phase checklist

1. Preparing for Production
2. Environment Variables (.env)
3. Gunicorn Web Server
4. Using Nginx as Reverse Proxy
5. Dockerizing Flask App
6. Deploying to Render
7. Deploying to PythonAnywhere
8. Deploying to AWS EC2

The phase at a glance

This phase exists to run the app somewhere other than your laptop. It assumes an application you are ready to expose, and once it is done you can build all of it, running on a public server.

diagram Diagram mermaid

  flowchart TD
  subgraph G0["Getting production-ready"]
    N0_0["Preparing for Production"]
    N0_1["Environment Variables (.env)"]
    N0_2["Gunicorn Web Server"]
  end
  subgraph G1["Serving it properly"]
    N1_0["Using Nginx as Reverse Proxy"]
    N1_1["Dockerizing Flask App"]
  end
  N0_2 --> N1_0
  subgraph G2["Somewhere to put it"]
    N2_0["Deploying to Render"]
    N2_1["Deploying to PythonAnywhere"]
    N2_2["Deploying to AWS EC2"]
  end
  N1_1 --> N2_0

Where this sits in the track

sketch The track, and what each phase unlocks p5.js Pause Restart

Each phase assumes the one before it. Click a phase to see what you can build once it is done.

The pages, in reading order

#	page
1	Preparing for Production
2	Environment Variables (.env)
3	Gunicorn Web Server
4	Using Nginx as Reverse Proxy
5	Dockerizing Flask App
6	Deploying to Render
7	Deploying to PythonAnywhere
8	Deploying to AWS EC2

8 pages. They are ordered so that each one only uses ideas from the pages above it — reading out of order mostly works, but the examples assume what came before.

Check yourself

pch.quizTag pch.quizDefaultTitle

1. Why is the Flask development server not used in production?

   A it cannot serve HTML B it is single-process by default, unhardened, and prints a warning saying so C it requires debug mode D it does not support HTTPS at all
   pch.quizShowAnswer

   B — it is single-process by default, unhardened, and prints a warning saying so — Werkzeug prints the warning on every start. Gunicorn or uWSGI runs the app, and Nginx usually sits in front of it.

2. Why do Environment Variables come before any hosting page in this phase?

   A hosting providers require a .env file B every deployment target needs the same thing: configuration and secrets supplied from outside the code C .env files are only used locally D it is alphabetical
   pch.quizShowAnswer

   B — every deployment target needs the same thing: configuration and secrets supplied from outside the code — Render, PythonAnywhere, Docker and EC2 differ in how you supply them, not in whether you need them. Learning the principle once makes each host a detail.

3. What do the phase overview pages give you that the individual pages do not?

   A the full code for each topic B the reading order, what the phase assumes, and what you can build once it is done C a downloadable project template D the deployment configuration
   pch.quizShowAnswer

   B — the reading order, what the phase assumes, and what you can build once it is done — Each overview lists its pages in sidebar order and names the phase's prerequisites and outcome, so you can tell whether you are ready for it.