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# Copyright 2011 OpenStack Foundation.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""Base class(es) for WSGI Middleware."""
from inspect import getargspec
import webob.dec
from oslo_config import cfg
class ConfigurableMiddleware(object):
"""Base WSGI middleware wrapper.
These classes require an application to be initialized that will be called
next. By default the middleware will simply call its wrapped app, or you
can override __call__ to customize its behavior.
"""
@classmethod
def factory(cls, global_conf, **local_conf):
"""Factory method for paste.deploy."""
conf = global_conf.copy() if global_conf else {}
conf.update(local_conf)
def middleware_filter(app):
return cls(app, conf)
return middleware_filter
def __init__(self, application, conf=None):
"""Base middleware constructor
:param conf: a dict of options or a cfg.ConfigOpts object
"""
self.application = application
# NOTE(sileht): If the configuration come from oslo.config
# just use it.
if isinstance(conf, cfg.ConfigOpts):
self.conf = {}
self.oslo_conf = conf
else:
self.conf = conf or {}
if "oslo_config_project" in self.conf:
if 'oslo_config_file' in self.conf:
default_config_files = [self.conf['oslo_config_file']]
else:
default_config_files = None
self.oslo_conf = cfg.ConfigOpts()
self.oslo_conf([], project=self.conf['oslo_config_project'],
default_config_files=default_config_files,
validate_default_values=True)
else:
# Fallback to global object
self.oslo_conf = cfg.CONF
def _conf_get(self, key, group="oslo_middleware"):
if key in self.conf:
# Validate value type
self.oslo_conf.set_override(key, self.conf[key], group=group,
enforce_type=True)
return getattr(getattr(self.oslo_conf, group), key)
@staticmethod
def process_request(req):
"""Called on each request.
If this returns None, the next application down the stack will be
executed. If it returns a response then that response will be returned
and execution will stop here.
"""
return None
@staticmethod
def process_response(response, request=None):
"""Do whatever you'd like to the response."""
return response
@webob.dec.wsgify
def __call__(self, req):
response = self.process_request(req)
if response:
return response
response = req.get_response(self.application)
(args, varargs, varkw, defaults) = getargspec(self.process_response)
if 'request' in args:
return self.process_response(response, request=req)
return self.process_response(response)
class Middleware(ConfigurableMiddleware):
"""Legacy base WSGI middleware wrapper.
Legacy interface that doesn't pass configuration options
to the middleware when it's loaded via paste.deploy.
"""
@classmethod
def factory(cls, global_conf, **local_conf):
"""Factory method for paste.deploy."""
return cls
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