Falcon§

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

1. Install Unit with a Python 3.5+ language module.

2. Create a virtual environment to install Falcon’s PIP package, for instance:

   $ cd /path/to/app/
   $ python --version
         Python X.Y.Z
   $ python -m venv venv
   $ source venv/bin/activate
   $ pip install falcon
   $ deactivate
   

   Warning

   Create your virtual environment with a Python version that matches the language module from Step 1 up to the minor number (X.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 an updated version of the quickstart app:

   WSGI

   import falcon
   
   
   # Falcon follows the REST architectural style, meaning (among
   # other things) that you think in terms of resources and state
   # transitions, which map to HTTP verbs.
   class HelloUnitResource:
       def on_get(self, req, resp):
           """Handles GET requests"""
           resp.status = falcon.HTTP_200  # This is the default status
           resp.content_type = falcon.MEDIA_TEXT  # Default is JSON, so override
           resp.text = ('Hello, Unit!')
   
   # falcon.App instances are callable WSGI apps
   # in larger applications the app is created in a separate file
   app = falcon.App()
   
   # Resources are represented by long-lived class instances
   hellounit = HelloUnitResource()
   
   # hellounit will handle all requests to the '/unit' URL path
   app.add_route('/unit', hellounit)
   

   Note that we’ve dropped the server code; save the file as /path/to/app/wsgi.py.

   ASGI

   import falcon
   import falcon.asgi
   
   
   # Falcon follows the REST architectural style, meaning (among
   # other things) that you think in terms of resources and state
   # transitions, which map to HTTP verbs.
   class HelloUnitResource:
       async def on_get(self, req, resp):
           """Handles GET requests"""
           resp.status = falcon.HTTP_200  # This is the default status
           resp.content_type = falcon.MEDIA_TEXT  # Default is JSON, so override
           resp.text = ('Hello, Unit!')
   
   # falcon.asgi.App instances are callable ASGI apps...
   # in larger applications the app is created in a separate file
   app = falcon.asgi.App()
   
   # Resources are represented by long-lived class instances
   hellounit = HelloUnitResource()
   
   # hellounit will handle all requests to the '/unit' URL path
   app.add_route('/unit', hellounit)
   

   Save the file as /path/to/app/asgi.py.

4. Run the following command so Unit can access the application directory:

   # 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 configuration for Unit (use real values for type, home, module, protocol, and path):

   {
       "listeners": {
           "*:80": {
               "pass": "applications/falcon"
           }
       },
   
       "applications": {
           "falcon": {
               "type": "python X.Y",
               "path": "/path/to/app/",
               "home": "/path/to/app/venv/",
               "module": "module_basename",
               "protocol": "wsgi_or_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 -h 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/unit
   
         Hello, Unit!