werkzeug's ProxyMiddleware with Flask

Quick example how to use ProxyMiddleware with Flask Apps

Introduction

The purpose of this project is to present how to call different API versions using same host address.

It contains two Flask applications:

• one with /v1/hello endpoint - app_v1.py
• the other with /v2/hello endpoint - app_v2.py

What we want to achieve is when we call these enpoints, the Middleware application will redirect our request to appriopriate Flask application.

Prerequisities

• python3.10
• docker
• docker compose

app_v1.py and app_v2.py

Simple flask applications with one endpoint /hello.

app_middleware.py

Middleware layer - groups up our applications and redirects requests to them.

How to run

Manually

Install requirements:

pip install -r requirements.txt

or for running tests:

pip install -r requirements.txt -r requirements-test.txt

Run applications:

python app_v1.py
python app_v1.py
python app_middleware.py

Then run in browser:

• http://127.0.0.1:5555/v1/hello - returns {"msg":"Hello from app v1"}
• http://127.0.0.1:5555/v2/hello - returns {"msg":"Hello from app v2"}

If you run this manually you can also check:

• http://127.0.0.1:5000/v1/hello
• http://127.0.0.1:5001/v2/hello

Remember to check if ports 5000, 5001 and 5555 are available.

Docker compose

Build images and run compose:

docker compose build
docker compose up -d

Now you can run in browser:

• http://127.0.0.1:5555/v1/hello - returns {"msg":"Hello from app v1"}
• http://127.0.0.1:5555/v2/hello - returns {"msg":"Hello from app v2"}

In this case check if 5555 port is available, as app_v1 and app_v2 are not available outside the docker compose.

More info

Werkzeug's Basic HTTP Proxy