diff options
Diffstat (limited to 'nova/wsgi.py')
| -rw-r--r-- | nova/wsgi.py | 158 |
1 files changed, 147 insertions, 11 deletions
diff --git a/nova/wsgi.py b/nova/wsgi.py index e999f76a3..4f5307d80 100644 --- a/nova/wsgi.py +++ b/nova/wsgi.py @@ -21,7 +21,7 @@ Utility methods for working with WSGI servers """ -import json +import os import sys from xml.dom import minidom @@ -34,7 +34,14 @@ import webob import webob.dec import webob.exc +from paste import deploy + +from nova import flags from nova import log as logging +from nova import utils + + +FLAGS = flags.FLAGS class WritableLogger(object): @@ -76,10 +83,33 @@ class Server(object): class Application(object): -# TODO(gundlach): I think we should toss this class, now that it has no -# purpose. """Base WSGI application wrapper. Subclasses need to implement __call__.""" + @classmethod + def factory(cls, global_config, **local_config): + """Used for paste app factories in paste.deploy config fles. + + Any local configuration (that is, values under the [app:APPNAME] + section of the paste config) will be passed into the `__init__` method + as kwargs. + + A hypothetical configuration would look like: + + [app:wadl] + latest_version = 1.3 + paste.app_factory = nova.api.fancy_api:Wadl.factory + + which would result in a call to the `Wadl` class as + + import nova.api.fancy_api + fancy_api.Wadl(latest_version='1.3') + + You could of course re-implement the `factory` method in subclasses, + but using the kwarg passing it shouldn't be necessary. + + """ + return cls(**local_config) + def __call__(self, environ, start_response): r"""Subclasses will probably want to implement __call__ like this: @@ -117,20 +147,65 @@ class Application(object): class Middleware(Application): - """ - Base WSGI middleware wrapper. These classes require an application to be + """Base WSGI middleware. + + 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. """ - def __init__(self, application): # pylint: disable-msg=W0231 + @classmethod + def factory(cls, global_config, **local_config): + """Used for paste app factories in paste.deploy config fles. + + Any local configuration (that is, values under the [filter:APPNAME] + section of the paste config) will be passed into the `__init__` method + as kwargs. + + A hypothetical configuration would look like: + + [filter:analytics] + redis_host = 127.0.0.1 + paste.filter_factory = nova.api.analytics:Analytics.factory + + which would result in a call to the `Analytics` class as + + import nova.api.analytics + analytics.Analytics(app_from_paste, redis_host='127.0.0.1') + + You could of course re-implement the `factory` method in subclasses, + but using the kwarg passing it shouldn't be necessary. + + """ + def _factory(app): + return cls(app, **local_config) + return _factory + + def __init__(self, application): self.application = application + def process_request(self, 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 + + def process_response(self, response): + """Do whatever you'd like to the response.""" + return response + @webob.dec.wsgify - def __call__(self, req): # pylint: disable-msg=W0221 - """Override to implement middleware behavior.""" - return self.application + def __call__(self, req): + response = self.process_request(req) + if response: + return response + response = req.get_response(self.application) + return self.process_response(response) class Debug(Middleware): @@ -316,7 +391,7 @@ class Serializer(object): try: is_xml = (datastring[0] == '<') if not is_xml: - return json.loads(datastring) + return utils.loads(datastring) return self._from_xml(datastring) except: return None @@ -349,7 +424,7 @@ class Serializer(object): return result def _to_json(self, data): - return json.dumps(data) + return utils.dumps(data) def _to_xml(self, data): metadata = self.metadata.get('application/xml', {}) @@ -385,3 +460,64 @@ class Serializer(object): node = doc.createTextNode(str(data)) result.appendChild(node) return result + + +def paste_config_file(basename): + """Find the best location in the system for a paste config file. + + Search Order + ------------ + + The search for a paste config file honors `FLAGS.state_path`, which in a + version checked out from bzr will be the `nova` directory in the top level + of the checkout, and in an installation for a package for your distribution + will likely point to someplace like /etc/nova. + + This method tries to load places likely to be used in development or + experimentation before falling back to the system-wide configuration + in `/etc/nova/`. + + * Current working directory + * the `etc` directory under state_path, because when working on a checkout + from bzr this will point to the default + * top level of FLAGS.state_path, for distributions + * /etc/nova, which may not be diffrerent from state_path on your distro + + """ + + configfiles = [basename, + os.path.join(FLAGS.state_path, 'etc', basename), + os.path.join(FLAGS.state_path, basename), + '/etc/nova/%s' % basename] + for configfile in configfiles: + if os.path.exists(configfile): + return configfile + + +def load_paste_configuration(filename, appname): + """Returns a paste configuration dict, or None.""" + filename = os.path.abspath(filename) + config = None + try: + config = deploy.appconfig("config:%s" % filename, name=appname) + except LookupError: + pass + return config + + +def load_paste_app(filename, appname): + """Builds a wsgi app from a paste config, None if app not configured.""" + filename = os.path.abspath(filename) + app = None + try: + app = deploy.loadapp("config:%s" % filename, name=appname) + except LookupError: + pass + return app + + +def paste_config_to_flags(config, mixins): + for k, v in mixins.iteritems(): + value = config.get(k, v) + converted_value = FLAGS[k].parser.Parse(value) + setattr(FLAGS, k, converted_value) |