Migrated from waitress to gunicorn.

`waitress`, unlike `gunicorn`, doesn't provide an easy way to plug into
a WSGI socket that can be used for the websocket interface.

docs/source/conf.py

@@ -201,6 +201,7 @@ autodoc_default_options = {
 }
 
 autodoc_mock_imports = [
+    'gunicorn',
     'googlesamples.assistant.grpc.audio_helpers',
     'google.assistant.embedded',
     'google.assistant.library',

platypush/backend/http/__init__.py

@@ -3,7 +3,7 @@ import pathlib
 import secrets
 import threading
 
-from multiprocessing import Process
+from multiprocessing import Process, cpu_count
 
 try:
     from websockets.exceptions import ConnectionClosed  # type: ignore
@@ -11,10 +11,9 @@ try:
 except ImportError:
     from websockets import ConnectionClosed, serve as websocket_serve  # type: ignore
 
-import waitress
-
 from platypush.backend import Backend
 from platypush.backend.http.app import application
+from platypush.backend.http.wsgi import WSGIApplicationWrapper
 from platypush.bus.redis import RedisBus
 from platypush.config import Config
 from platypush.context import get_or_create_event_loop
@@ -174,7 +173,6 @@ class HttpBackend(Backend):
         ssl_capath=None,
         maps=None,
         secret_key_file=None,
-        flask_args=None,
         **kwargs,
     ):
         """
@@ -213,9 +211,6 @@ class HttpBackend(Backend):
         :param secret_key_file: Path to the file containing the secret key that will be used by Flask
             (default: ``~/.local/share/platypush/flask.secret.key``).
         :type secret_key_file: str
-
-        :param flask_args: Extra key-value arguments that should be passed to the Flask service.
-        :type flask_args: dict[str, str]
         """
 
         super().__init__(**kwargs)
@@ -239,7 +234,6 @@ class HttpBackend(Backend):
             self.resource_dirs = {}
 
         self.active_websockets = set()
-        self.flask_args = flask_args or {}
         self.ssl_context = (
             get_ssl_server_context(
                 ssl_cert=ssl_cert,
@@ -420,24 +414,18 @@ class HttpBackend(Backend):
     def _web_server_proc(self):
         def proc():
             self.logger.info('Starting local web server on port %s', self.port)
-            kwargs = {
-                'host': self.bind_address,
-                'port': self.port,
-            }
-
             assert isinstance(
                 self.bus, RedisBus
             ), 'The HTTP backend only works if backed by a Redis bus'
 
             application.config['redis_queue'] = self.bus.redis_queue
             application.secret_key = self._get_secret_key()
+            kwargs = {
+                'bind': f'{self.bind_address}:{self.port}',
+                'workers': (cpu_count() * 2) + 1,
+            }
 
-            if self.ssl_context:
-                kwargs['ssl_context'] = self.ssl_context
-            if self.flask_args:
-                kwargs.update(self.flask_args)
-
-            waitress.serve(application, **kwargs)
+            WSGIApplicationWrapper(f'{__package__}.app:application', kwargs).run()
 
         return proc
 

platypush/backend/http/wsgi/__init__.py

@@ -0,0 +1,21 @@
+from gunicorn.app.wsgiapp import WSGIApplication
+
+
+class WSGIApplicationWrapper(WSGIApplication):
+    """
+    Wrapper for the Flask application into a WSGI application.
+    """
+
+    def __init__(self, app_uri, options=None):
+        self.options = options or {}
+        self.app_uri = app_uri
+        super().__init__()
+
+    def load_config(self):
+        config = {
+            key: value
+            for key, value in self.options.items()
+            if key in self.cfg.settings and value is not None  # type: ignore
+        }
+        for key, value in config.items():
+            self.cfg.set(key.lower(), value)  # type: ignore

requirements.txt

@@ -2,24 +2,25 @@
 # Platypush common requirements
 ###
 
-pyyaml
-marshmallow
-marshmallow_dataclass
-python-prctl
-flask
-websockets
-redis
-python-dateutil
-tz
-frozendict
-requests
-sqlalchemy
 alembic
 bcrypt
-rsa
-zeroconf>=0.27.0
-paho-mqtt
-websocket-client
 croniter
+flask
+frozendict
+gunicorn
+marshmallow
+marshmallow_dataclass
+paho-mqtt
+python-dateutil
 python-magic
-waitress
+python-prctl
+pyyaml
+redis
+requests
+rsa
+simple_websocket
+sqlalchemy
+tz
+websocket-client
+wsproto
+zeroconf>=0.27.0

setup.py

@@ -65,6 +65,7 @@ setup(
         'croniter',
         'flask',
         'frozendict',
+        'gunicorn',
         'marshmallow',
         'marshmallow_dataclass',
         'python-dateutil',
@@ -75,7 +76,6 @@ setup(
         'rsa',
         'sqlalchemy',
         'tz',
-        'waitress',
         'websocket-client',
         'websockets',
         'wheel',