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.x.y
   $ 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.x 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. Set installation path permissions to secure access, for example:

   # chown -R app_user:app_group /path/to/app/
   

   Update the placeholders above with actual values, noting them for later use in Unit configuration.

5. Next, put together the FastAPI configuration for Unit:

   {
       "listeners": {
           "*:80": {
               "pass": "applications/fastapi"
           }
       },
   
       "applications": {
           "fastapi": {
               "type": "python 3.x",
               "user": "app_user",
               "group": "app_group",
               "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: