tailbone/tailbone/asgi.py

109 lines
3.2 KiB
Python

# -*- coding: utf-8; -*-
################################################################################
#
# Rattail -- Retail Software Framework
# Copyright © 2010-2022 Lance Edgar
#
# This file is part of Rattail.
#
# Rattail is free software: you can redistribute it and/or modify it under the
# terms of the GNU General Public License as published by the Free Software
# Foundation, either version 3 of the License, or (at your option) any later
# version.
#
# Rattail is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
# details.
#
# You should have received a copy of the GNU General Public License along with
# Rattail. If not, see <http://www.gnu.org/licenses/>.
#
################################################################################
"""
ASGI App Utilities
"""
from __future__ import unicode_literals, absolute_import
import os
import logging
import six
from six.moves import configparser
from rattail.util import load_object
from asgiref.wsgi import WsgiToAsgi
log = logging.getLogger(__name__)
class TailboneWsgiToAsgi(WsgiToAsgi):
"""
Custom WSGI -> ASGI wrapper, to add routing for websockets.
"""
async def __call__(self, scope, *args, **kwargs):
protocol = scope['type']
path = scope['path']
if protocol == 'websocket':
websockets = self.wsgi_application.registry.get(
'tailbone_websockets', {})
if path in websockets:
await websockets[path](scope, *args, **kwargs)
try:
await super().__call__(scope, *args, **kwargs)
except ValueError as e:
# The developer may wish to improve handling of this exception.
# See https://github.com/Pylons/pyramid_cookbook/issues/225 and
# https://asgi.readthedocs.io/en/latest/specs/www.html#websocket
pass
except Exception as e:
raise e
def make_asgi_app(main_app=None):
"""
This function returns an ASGI application.
"""
path = os.environ.get('TAILBONE_ASGI_CONFIG')
if not path:
raise RuntimeError("You must define TAILBONE_ASGI_CONFIG env variable.")
# make a config parser good enough to load pyramid settings
configdir = os.path.dirname(path)
parser = configparser.ConfigParser(defaults={'__file__': path,
'here': configdir})
# read the config file
parser.read(path)
# parse the settings needed for pyramid app
settings = dict(parser.items('app:main'))
if isinstance(main_app, six.string_types):
make_wsgi_app = load_object(main_app)
elif callable(main_app):
make_wsgi_app = main_app
else:
if main_app:
log.warning("specified main app of unknown type: %s", main_app)
make_wsgi_app = load_object('tailbone.app:main')
# construct a pyramid app "per usual"
app = make_wsgi_app({}, **settings)
# then wrap it with ASGI
return TailboneWsgiToAsgi(app)
def asgi_main():
"""
This function returns an ASGI application.
"""
return make_asgi_app()