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/  # Path to the application directory; use a real path in your configuration
   $ python --version  # Make sure your virtual environment version matches the module version
         Python X.Y.Z  # Major version, minor version, and revision number
   $ python -m venv venv  # Arbitrary name of the virtual environment
   $ source venv/bin/activate  # Name of the virtual environment from the previous command
   $ 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
   • ASGI

      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.

   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. Change ownership:

   Run the following command (as root) so Unit can access the application directory (If the application uses several directories, run the command for each one):

   # chown -R unit:unit /path/to/app/  # User and group that Unit's router runs as by default
      

   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",
               "type_comment": "Must match language module version and virtual environment version",
               "path": "/path/to/app/",
               "path_comment": "Path to the WSGI module; use a real path in your configuration",
               "home": "/path/to/app/venv/",
               "home_comment": "Path to the virtual environment, if any; use a real path in your configuration",
               "module": "module_basename",
               "module_comment": "WSGI/ASGI module basename with extension omitted, such as 'wsgi' or 'asgi' from Step 3",
               "protocol": "wsgi_or_asgi",
               "protocol_comment": "'wsgi' or 'asgi', as appropriate",
               "callable": "app",
               "callable_comment": "Name of the callable in the module to run"
            }
         }
      }
   

6. Upload the updated configuration.

   Assuming the JSON above was added to config.json. Run the following command as root:

   # curl -X PUT --data-binary @config.json --unix-socket \
         /path/to/control.unit.sock \  # Path to Unit's control socket in your installation
         http://localhost/config/      # Path to the config section in Unit's control API
      

   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!