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OpenStack Study: extensions.py**** CubicPower OpenStack Study ****
# Copyright 2011 OpenStack Foundation # Copyright 2011 Justin Santa Barbara # 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. import abc import functools import os import six import webob.dec import webob.exc import nova.api.openstack from nova.api.openstack import wsgi from nova.api.openstack import xmlutil from nova import exception from nova.openstack.common.gettextutils import _ from nova.openstack.common import importutils from nova.openstack.common import log as logging import nova.policy LOG = logging.getLogger(__name__)
**** CubicPower OpenStack Study **** class ExtensionDescriptor(object): """Base class that
**** CubicPower OpenStack Study **** def __init__(self, ext_mgr): """Register extension with the extension manager.""" ext_mgr.register(self) self.ext_mgr = ext_mgr
**** CubicPower OpenStack Study **** def get_resources(self): """List of extensions.ResourceExtension extension objects. Resources define new nouns, and are accessible through URLs. """ resources = [] return resources
**** CubicPower OpenStack Study **** def get_controller_extensions(self): """List of extensions.ControllerExtension extension objects. Controller extensions are used to extend existing controllers. """ controller_exts = [] return controller_exts @classmethod
**** CubicPower OpenStack Study **** def nsmap(cls): """Synthesize a namespace map from extension.""" # Start with a base nsmap nsmap = ext_nsmap.copy() # Add the namespace for the extension nsmap[cls.alias] = cls.namespace return nsmap @classmethod
**** CubicPower OpenStack Study **** def xmlname(cls, name): """Synthesize element and attribute names.""" return '{%s}%s' % (cls.namespace, name) def make_ext(elem): elem.set('name') elem.set('namespace') elem.set('alias') elem.set('updated') desc = xmlutil.SubTemplateElement(elem, 'description') desc.text = 'description' xmlutil.make_links(elem, 'links') ext_nsmap = {None: xmlutil.XMLNS_COMMON_V10, 'atom': xmlutil.XMLNS_ATOM}
**** CubicPower OpenStack Study **** def make_ext(elem): elem.set('name') elem.set('namespace') elem.set('alias') elem.set('updated') desc = xmlutil.SubTemplateElement(elem, 'description') desc.text = 'description' xmlutil.make_links(elem, 'links') ext_nsmap = {None: xmlutil.XMLNS_COMMON_V10, 'atom': xmlutil.XMLNS_ATOM}
**** CubicPower OpenStack Study **** class ExtensionTemplate(xmlutil.TemplateBuilder):
**** CubicPower OpenStack Study **** def construct(self): root = xmlutil.TemplateElement('extension', selector='extension') make_ext(root) return xmlutil.MasterTemplate(root, 1, nsmap=ext_nsmap)
**** CubicPower OpenStack Study **** class ExtensionsTemplate(xmlutil.TemplateBuilder):
**** CubicPower OpenStack Study **** def construct(self): root = xmlutil.TemplateElement('extensions') elem = xmlutil.SubTemplateElement(root, 'extension', selector='extensions') make_ext(elem) return xmlutil.MasterTemplate(root, 1, nsmap=ext_nsmap)
**** CubicPower OpenStack Study **** class ExtensionsController(wsgi.Resource):
**** CubicPower OpenStack Study **** def __init__(self, extension_manager): self.extension_manager = extension_manager super(ExtensionsController, self).__init__(None)
**** CubicPower OpenStack Study **** def _translate(self, ext): ext_data = {} ext_data['name'] = ext.name ext_data['alias'] = ext.alias ext_data['description'] = ext.__doc__ ext_data['namespace'] = ext.namespace ext_data['updated'] = ext.updated ext_data['links'] = [] # TODO(dprince): implement extension links return ext_data @wsgi.serializers(xml=ExtensionsTemplate)
**** CubicPower OpenStack Study **** def index(self, req): extensions = [] for ext in self.extension_manager.sorted_extensions(): extensions.append(self._translate(ext)) return dict(extensions=extensions) @wsgi.serializers(xml=ExtensionTemplate)
**** CubicPower OpenStack Study **** def show(self, req, id): try: # NOTE(dprince): the extensions alias is used as the 'id' for show ext = self.extension_manager.extensions[id] except KeyError: raise webob.exc.HTTPNotFound() return dict(extension=self._translate(ext))
**** CubicPower OpenStack Study **** def delete(self, req, id): raise webob.exc.HTTPNotFound()
**** CubicPower OpenStack Study **** def create(self, req, body): raise webob.exc.HTTPNotFound()
**** CubicPower OpenStack Study **** class ExtensionManager(object): """Load extensions from the configured extension path. See nova/tests/api/openstack/volume/extensions/foxinsocks.py or an example extension implementation. """
**** CubicPower OpenStack Study **** def sorted_extensions(self): if self.sorted_ext_list is None: self.sorted_ext_list = sorted(self.extensions.iteritems()) for _alias, ext in self.sorted_ext_list: yield ext
**** CubicPower OpenStack Study **** def is_loaded(self, alias): return alias in self.extensions
**** CubicPower OpenStack Study **** def register(self, ext): # Do nothing if the extension doesn't check out if not self._check_extension(ext): return alias = ext.alias LOG.audit(_('Loaded extension: %s'), alias) if alias in self.extensions: raise exception.NovaException("Found duplicate extension: %s" % alias) self.extensions[alias] = ext self.sorted_ext_list = None
**** CubicPower OpenStack Study **** def get_resources(self): """Returns a list of ResourceExtension objects.""" resources = [] resources.append(ResourceExtension('extensions', ExtensionsController(self))) for ext in self.sorted_extensions(): try: resources.extend(ext.get_resources()) except AttributeError: # NOTE(dprince): Extension aren't required to have resource # extensions pass return resources
**** CubicPower OpenStack Study **** def get_controller_extensions(self): """Returns a list of ControllerExtension objects.""" controller_exts = [] for ext in self.sorted_extensions(): try: get_ext_method = ext.get_controller_extensions except AttributeError: # NOTE(Vek): Extensions aren't required to have # controller extensions continue controller_exts.extend(get_ext_method()) return controller_exts
**** CubicPower OpenStack Study **** def _check_extension(self, extension): """Checks for required methods in extension objects.""" try: LOG.debug(_('Ext name: %s'), extension.name) LOG.debug(_('Ext alias: %s'), extension.alias) LOG.debug(_('Ext description: %s'), ' '.join(extension.__doc__.strip().split())) LOG.debug(_('Ext namespace: %s'), extension.namespace) LOG.debug(_('Ext updated: %s'), extension.updated) except AttributeError as ex: LOG.exception(_("Exception loading extension: %s"), unicode(ex)) return False return True
**** CubicPower OpenStack Study **** def load_extension(self, ext_factory): """Execute an extension factory. Loads an extension. The 'ext_factory' is the name of a callable that will be imported and called with one argument--the extension manager. The factory callable is expected to call the register() method at least once. """ LOG.debug(_("Loading extension %s"), ext_factory) if isinstance(ext_factory, six.string_types): # Load the factory factory = importutils.import_class(ext_factory) else: factory = ext_factory # Call it LOG.debug(_("Calling extension factory %s"), ext_factory) factory(self)
**** CubicPower OpenStack Study **** def _load_extensions(self): """Load extensions specified on the command line.""" extensions = list(self.cls_list) for ext_factory in extensions: try: self.load_extension(ext_factory) except Exception as exc: LOG.warn(_('Failed to load extension %(ext_factory)s: ' '%(exc)s'), {'ext_factory': ext_factory, 'exc': exc})
**** CubicPower OpenStack Study **** class ControllerExtension(object): """Extend core controllers of nova OpenStack API. Provide a way to extend existing nova OpenStack API core controllers. """
**** CubicPower OpenStack Study **** def __init__(self, extension, collection, controller): self.extension = extension self.collection = collection self.controller = controller
**** CubicPower OpenStack Study **** class ResourceExtension(object): """Add top level resources to the OpenStack API in nova."""
**** CubicPower OpenStack Study **** def __init__(self, collection, controller=None, parent=None, collection_actions=None, member_actions=None, custom_routes_fn=None, inherits=None, member_name=None): if not collection_actions: collection_actions = {} if not member_actions: member_actions = {} self.collection = collection self.controller = controller self.parent = parent self.collection_actions = collection_actions self.member_actions = member_actions self.custom_routes_fn = custom_routes_fn self.inherits = inherits self.member_name = member_name def load_standard_extensions(ext_mgr, logger, path, package, ext_list=None): """Registers all standard API extensions.""" # Walk through all the modules in our directory... our_dir = path[0] for dirpath, dirnames, filenames in os.walk(our_dir): # Compute the relative package name from the dirpath relpath = os.path.relpath(dirpath, our_dir) if relpath == '.': relpkg = '' else: relpkg = '.%s' % '.'.join(relpath.split(os.sep)) # Now, consider each file in turn, only considering .py files for fname in filenames: root, ext = os.path.splitext(fname) # Skip __init__ and anything that's not .py if ext != '.py' or root == '__init__': continue # Try loading it classname = "%s%s" % (root[0].upper(), root[1:]) classpath = ("%s%s.%s.%s" % (package, relpkg, root, classname)) if ext_list is not None and classname not in ext_list: logger.debug("Skipping extension: %s" % classpath) continue try: ext_mgr.load_extension(classpath) except Exception as exc: logger.warn(_('Failed to load extension %(classpath)s: ' '%(exc)s'), {'classpath': classpath, 'exc': exc}) # Now, let's consider any subdirectories we may have... subdirs = [] for dname in dirnames: # Skip it if it does not have __init__.py if not os.path.exists(os.path.join(dirpath, dname, '__init__.py')): continue # If it has extension(), delegate... ext_name = "%s%s.%s.extension" % (package, relpkg, dname) try: ext = importutils.import_class(ext_name) except ImportError: # extension() doesn't exist on it, so we'll explore # the directory for ourselves subdirs.append(dname) else: try: ext(ext_mgr) except Exception as exc: logger.warn(_('Failed to load extension %(ext_name)s:' '%(exc)s'), {'ext_name': ext_name, 'exc': exc}) # Update the list of directories we'll explore... dirnames[:] = subdirs def core_authorizer(api_name, extension_name):
**** CubicPower OpenStack Study **** def load_standard_extensions(ext_mgr, logger, path, package, ext_list=None): """Registers all standard API extensions.""" # Walk through all the modules in our directory... our_dir = path[0] for dirpath, dirnames, filenames in os.walk(our_dir): # Compute the relative package name from the dirpath relpath = os.path.relpath(dirpath, our_dir) if relpath == '.': relpkg = '' else: relpkg = '.%s' % '.'.join(relpath.split(os.sep)) # Now, consider each file in turn, only considering .py files for fname in filenames: root, ext = os.path.splitext(fname) # Skip __init__ and anything that's not .py if ext != '.py' or root == '__init__': continue # Try loading it classname = "%s%s" % (root[0].upper(), root[1:]) classpath = ("%s%s.%s.%s" % (package, relpkg, root, classname)) if ext_list is not None and classname not in ext_list: logger.debug("Skipping extension: %s" % classpath) continue try: ext_mgr.load_extension(classpath) except Exception as exc: logger.warn(_('Failed to load extension %(classpath)s: ' '%(exc)s'), {'classpath': classpath, 'exc': exc}) # Now, let's consider any subdirectories we may have... subdirs = [] for dname in dirnames: # Skip it if it does not have __init__.py if not os.path.exists(os.path.join(dirpath, dname, '__init__.py')): continue # If it has extension(), delegate... ext_name = "%s%s.%s.extension" % (package, relpkg, dname) try: ext = importutils.import_class(ext_name) except ImportError: # extension() doesn't exist on it, so we'll explore # the directory for ourselves subdirs.append(dname) else: try: ext(ext_mgr) except Exception as exc: logger.warn(_('Failed to load extension %(ext_name)s:' '%(exc)s'), {'ext_name': ext_name, 'exc': exc}) # Update the list of directories we'll explore... dirnames[:] = subdirs
**** CubicPower OpenStack Study **** def core_authorizer(api_name, extension_name):
**** CubicPower OpenStack Study **** def authorize(context, target=None, action=None): if target is None: target = {'project_id': context.project_id, 'user_id': context.user_id} if action is None: act = '%s:%s' % (api_name, extension_name) else: act = '%s:%s:%s' % (api_name, extension_name, action) nova.policy.enforce(context, act, target) return authorize def extension_authorizer(api_name, extension_name): return core_authorizer('%s_extension' % api_name, extension_name) def soft_extension_authorizer(api_name, extension_name): hard_authorize = extension_authorizer(api_name, extension_name)
**** CubicPower OpenStack Study **** def extension_authorizer(api_name, extension_name): return core_authorizer('%s_extension' % api_name, extension_name)
**** CubicPower OpenStack Study **** def soft_extension_authorizer(api_name, extension_name): hard_authorize = extension_authorizer(api_name, extension_name)
**** CubicPower OpenStack Study **** def authorize(context, action=None): try: hard_authorize(context, action=action) return True except exception.NotAuthorized: return False return authorize def check_compute_policy(context, action, target, scope='compute'): _action = '%s:%s' % (scope, action) nova.policy.enforce(context, _action, target) @six.add_metaclass(abc.ABCMeta)
**** CubicPower OpenStack Study **** def check_compute_policy(context, action, target, scope='compute'): _action = '%s:%s' % (scope, action) nova.policy.enforce(context, _action, target) @six.add_metaclass(abc.ABCMeta)
**** CubicPower OpenStack Study **** class V3APIExtensionBase(object): """Abstract base class for all V3 API extensions. All V3 API extensions must derive from this class and implement the abstract methods get_resources and get_controller_extensions even if they just return an empty list. The extensions must also
**** CubicPower OpenStack Study **** def __init__(self, extension_info): self.extension_info = extension_info @abc.abstractmethod
**** CubicPower OpenStack Study **** def get_resources(self): """Return a list of resources extensions. The extensions should return a list of ResourceExtension objects. This list may be empty. """ pass @abc.abstractmethod
**** CubicPower OpenStack Study **** def get_controller_extensions(self): """Return a list of controller extensions. The extensions should return a list of ControllerExtension objects. This list may be empty. """ pass @abc.abstractproperty
**** CubicPower OpenStack Study **** def name(self): """Name of the extension.""" pass @abc.abstractproperty
**** CubicPower OpenStack Study **** def alias(self): """Alias for the extension.""" pass @abc.abstractproperty
**** CubicPower OpenStack Study **** def version(self): """Version of the extension.""" pass def expected_errors(errors): """Decorator for v3 API methods which specifies expected exceptions. Specify which exceptions may occur when an API method is called. If an unexpected exception occurs then return a 500 instead and ask the user of the API to file a bug report. """
**** CubicPower OpenStack Study **** def expected_errors(errors): """Decorator for v3 API methods which specifies expected exceptions. Specify which exceptions may occur when an API method is called. If an unexpected exception occurs then return a 500 instead and ask the user of the API to file a bug report. """
**** CubicPower OpenStack Study **** def decorator(f): @functools.wraps(f) def wrapped(*args, **kwargs): try: return f(*args, **kwargs) except Exception as exc: if isinstance(exc, webob.exc.WSGIHTTPException): if isinstance(errors, int): t_errors = (errors,) else: t_errors = errors if exc.code in t_errors: raise elif isinstance(exc, exception.PolicyNotAuthorized): # Note(cyeoh): Special case to handle # PolicyNotAuthorized exceptions so every # extension method does not need to wrap authorize # calls. ResourceExceptionHandler silently # converts NotAuthorized to HTTPForbidden raise elif isinstance(exc, exception.ValidationError): # Note(oomichi): Handle a validation error, which # happens due to invalid API parameters, as an # expected error. raise LOG.exception(_("Unexpected exception in API method")) msg = _('Unexpected API Error. Please report this at ' 'http://bugs.launchpad.net/nova/ and attach the Nova ' 'API log if possible.\n%s') % type(exc) raise webob.exc.HTTPInternalServerError(explanation=msg) return wrapped return decorator
**** CubicPower OpenStack Study **** def wrapped(*args, **kwargs): try: return f(*args, **kwargs) except Exception as exc: if isinstance(exc, webob.exc.WSGIHTTPException): if isinstance(errors, int): t_errors = (errors,) else: t_errors = errors if exc.code in t_errors: raise elif isinstance(exc, exception.PolicyNotAuthorized): # Note(cyeoh): Special case to handle # PolicyNotAuthorized exceptions so every # extension method does not need to wrap authorize # calls. ResourceExceptionHandler silently # converts NotAuthorized to HTTPForbidden raise elif isinstance(exc, exception.ValidationError): # Note(oomichi): Handle a validation error, which # happens due to invalid API parameters, as an # expected error. raise LOG.exception(_("Unexpected exception in API method")) msg = _('Unexpected API Error. Please report this at ' 'http://bugs.launchpad.net/nova/ and attach the Nova ' 'API log if possible.\n%s') % type(exc) raise webob.exc.HTTPInternalServerError(explanation=msg) return wrapped return decorator
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