FastAPI§

To run apps built with the FastAPI web framework using Unit:

1. Install Unit with a Python 3.6+ language module.

2. Create a virtual environment to install FastAPI’s PIP package:

   $ cd /path/to/app/
   $ python3 --version
         Python 3.Y.Z
   $ python3 -m venv venv
   $ source venv/bin/activate
   $ pip install fastapi
   $ deactivate
   

   Warning

   Create your virtual environment with a Python version that matches the language module from Step 1 up to the minor number (3.Y in this example). Also, the app type in Step 5 must resolve to a similarly matching version; Unit doesn’t infer it from the environment.

3. Let’s try a version of a tutorial app, saving it as /path/to/app/asgi.py:

   from fastapi import FastAPI
   
   app = FastAPI()
   
   @app.get("/")
   async def root():
       return {"message": "Hello, World!"}
   

   Note

   For something more true-to-life, try the RealWorld example app; just install all its dependencies in the same virtual environment where you’ve installed FastAPI and add the app’s environment variables like DB_CONNECTION or SECRET_KEY directly to the app configuration in Unit instead of the .env file.

4. Run the following command for each directory containing app code or data so Unit can access it:

   # chown -R unit:unit /path/to/app/
   

   Note

   The unit:unit user-group pair is available only with official packages, Docker images, and some third-party repos. Otherwise, account names may differ; run the ps aux | grep unitd command to be sure.

   For further details, including permissions, see the security checklist.

5. Next, prepare the FastAPI configuration for Unit (use real values for type, home, and path):

   {
       "listeners": {
           "*:80": {
               "pass": "applications/fastapi"
           }
       },
   
       "applications": {
           "fastapi": {
               "type": "python 3.Y",
               "path": "/path/to/app/",
               "home": "/path/to/app/venv/",
               "module": "asgi",
               "callable": "app"
           }
       }
   }
   

6. Upload the updated configuration. Assuming the JSON above was added to config.json:

   # curl -X PUT --data-binary @config.json --unix-socket \
          /path/to/control.unit.sock http://localhost/config/
   

   Note

   The control socket path may vary; run unitd --help or see Startup and Shutdown for details.

   After a successful update, your app should be available on the listener’s IP address and port:

   $ curl http://localhost
   
         Hello, World!
   

   Alternatively, try FastAPI’s nifty self-documenting features: