Source code for horizon.exceptions

# Copyright 2012 Nebula, Inc.
#
#    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.

"""
Exceptions raised by the Horizon code and the machinery for handling them.
"""

import logging
import os
import sys

import six

from django.core.management import color_style  # noqa
from django.http import HttpRequest  # noqa
from django.utils import encoding
from django.utils.translation import ugettext_lazy as _
from django.views.debug import CLEANSED_SUBSTITUTE  # noqa
from django.views.debug import SafeExceptionReporterFilter  # noqa

from horizon.conf import HORIZON_CONFIG  # noqa
from horizon import messages

LOG = logging.getLogger(__name__)


[docs]class HorizonReporterFilter(SafeExceptionReporterFilter): """Error report filter that's always active, even in DEBUG mode.""" def is_active(self, request): return True
[docs]class HorizonException(Exception): """Base exception class for distinguishing our own exception classes.""" pass
[docs]class Http302(HorizonException): """Error class which can be raised from within a handler to cause an early bailout and redirect at the middleware level. """ status_code = 302 def __init__(self, location, message=None): self.location = location self.message = message
[docs]class NotAuthorized(HorizonException): """Raised whenever a user attempts to access a resource which they do not have permission-based access to (such as when failing the :func:`~horizon.decorators.require_perms` decorator). The included :class:`~horizon.middleware.HorizonMiddleware` catches ``NotAuthorized`` and handles it gracefully by displaying an error message and redirecting the user to a login page. """ status_code = 401
[docs]class NotAuthenticated(HorizonException): """Raised when a user is trying to make requests and they are not logged in. The included :class:`~horizon.middleware.HorizonMiddleware` catches ``NotAuthenticated`` and handles it gracefully by displaying an error message and redirecting the user to a login page. """ status_code = 403
[docs]class NotFound(HorizonException): """Generic error to replace all "Not Found"-type API errors.""" status_code = 404
[docs]class Conflict(HorizonException): """Generic error to replace all "Conflict"-type API errors.""" status_code = 409
[docs]class BadRequest(HorizonException): """Generic error to replace all "BadRequest"-type API errors.""" status_code = 400
[docs]class RecoverableError(HorizonException): """Generic error to replace any "Recoverable"-type API errors.""" status_code = 100 # HTTP status code "Continue"
[docs]class ServiceCatalogException(HorizonException): """Raised when a requested service is not available in the ``ServiceCatalog`` returned by Keystone. """ def __init__(self, service_name): message = 'Invalid service catalog service: %s' % service_name super(ServiceCatalogException, self).__init__(message)
@six.python_2_unicode_compatible
[docs]class AlreadyExists(HorizonException): """Exception to be raised when trying to create an API resource which already exists. """ def __init__(self, name, resource_type): self.attrs = {"name": name, "resource": resource_type} self.msg = _('A %(resource)s with the name "%(name)s" already exists.') def __repr__(self): return self.msg % self.attrs def __str__(self): return self.msg % self.attrs
@six.python_2_unicode_compatible
[docs]class GetFileError(HorizonException): """Exception to be raised when the value of get_file did not start with https:// or http:// """ def __init__(self, name, resource_type): self.attrs = {"name": name, "resource": resource_type} self.msg = _('The value of %(resource)s is %(name)s inside the ' 'template. When launching a stack from this interface,' ' the value must start with "http://" or "https://"') def __repr__(self): return '<%s name=%r resource_type=%r>' % (self.__class__.__name__, self.attrs['name'], self.attrs['resource_type']) def __str__(self): return self.msg % self.attrs
[docs]class ConfigurationError(HorizonException): """Exception to be raised when invalid settings have been provided.""" pass
[docs]class NotAvailable(HorizonException): """Exception to be raised when something is not available.""" pass
[docs]class WorkflowError(HorizonException): """Exception to be raised when something goes wrong in a workflow.""" pass
[docs]class WorkflowValidationError(HorizonException): """Exception raised during workflow validation if required data is missing, or existing data is not valid. """ pass
[docs]class MessageFailure(HorizonException): """Exception raised during message notification.""" pass
[docs]class HandledException(HorizonException): """Used internally to track exceptions that have gone through :func:`horizon.exceptions.handle` more than once. """ def __init__(self, wrapped): self.wrapped = wrapped
UNAUTHORIZED = tuple(HORIZON_CONFIG['exceptions']['unauthorized']) UNAUTHORIZED += (NotAuthorized,) NOT_FOUND = tuple(HORIZON_CONFIG['exceptions']['not_found']) NOT_FOUND += (GetFileError,) RECOVERABLE = (AlreadyExists, Conflict, NotAvailable, ServiceCatalogException, BadRequest) RECOVERABLE += tuple(HORIZON_CONFIG['exceptions']['recoverable']) def error_color(msg): return color_style().ERROR_OUTPUT(msg)
[docs]def check_message(keywords, message): """Checks an exception for given keywords and raises a new ``ActionError`` with the desired message if the keywords are found. This allows selective control over API error messages. """ exc_type, exc_value, exc_traceback = sys.exc_info() if set(str(exc_value).split(" ")).issuperset(set(keywords)): exc_value.message = message raise
def handle_unauthorized(request, message, redirect, ignore, escalate, handled, force_silence, force_log, log_method, log_entry, log_level): if ignore: return NotAuthorized if not force_silence and not handled: log_method(error_color("Unauthorized: %s" % log_entry)) if not handled: if message: message = _("Unauthorized: %s") % message # We get some pretty useless error messages back from # some clients, so let's define our own fallback. fallback = _("Unauthorized. Please try logging in again.") messages.error(request, message or fallback) # Escalation means logging the user out and raising NotAuthorized # so the middleware will redirect them appropriately. if escalate: # Prevents creation of circular import. django.contrib.auth # requires openstack_dashboard.settings to be loaded (by trying to # access settings.CACHES in django.core.caches) while # openstack_dashboard.settings requires django.contrib.auth to be # loaded while importing openstack_auth.utils from django.contrib.auth import logout # noqa logout(request) raise NotAuthorized # Otherwise continue and present our "unauthorized" error message. return NotAuthorized def handle_notfound(request, message, redirect, ignore, escalate, handled, force_silence, force_log, log_method, log_entry, log_level): if not force_silence and not handled and (not ignore or force_log): log_method(error_color("Not Found: %s" % log_entry)) if not ignore and not handled: messages.error(request, message or log_entry) if redirect: raise Http302(redirect) if not escalate: return NotFound # return to normal code flow def handle_recoverable(request, message, redirect, ignore, escalate, handled, force_silence, force_log, log_method, log_entry, log_level): if not force_silence and not handled and (not ignore or force_log): # Default recoverable error to WARN log level log_method = getattr(LOG, log_level or "warning") log_method(error_color("Recoverable error: %s" % log_entry)) if not ignore and not handled: messages.error(request, message or log_entry) if redirect: raise Http302(redirect) if not escalate: return RecoverableError # return to normal code flow HANDLE_EXC_METHODS = [ {'exc': UNAUTHORIZED, 'handler': handle_unauthorized, 'set_wrap': False, 'escalate': True}, {'exc': NOT_FOUND, 'handler': handle_notfound, 'set_wrap': True}, {'exc': RECOVERABLE, 'handler': handle_recoverable, 'set_wrap': True}, ]
[docs]def handle(request, message=None, redirect=None, ignore=False, escalate=False, log_level=None, force_log=None): """Centralized error handling for Horizon. Because Horizon consumes so many different APIs with completely different ``Exception`` types, it's necessary to have a centralized place for handling exceptions which may be raised. Exceptions are roughly divided into 3 types: #. ``UNAUTHORIZED``: Errors resulting from authentication or authorization problems. These result in being logged out and sent to the login screen. #. ``NOT_FOUND``: Errors resulting from objects which could not be located via the API. These generally result in a user-facing error message, but are otherwise returned to the normal code flow. Optionally a redirect value may be passed to the error handler so users are returned to a different view than the one requested in addition to the error message. #. ``RECOVERABLE``: Generic API errors which generate a user-facing message but drop directly back to the regular code flow. All other exceptions bubble the stack as normal unless the ``ignore`` argument is passed in as ``True``, in which case only unrecognized errors are bubbled. If the exception is not re-raised, an appropriate wrapper exception class indicating the type of exception that was encountered will be returned. """ exc_type, exc_value, exc_traceback = sys.exc_info() log_method = getattr(LOG, log_level or "exception") force_log = force_log or os.environ.get("HORIZON_TEST_RUN", False) force_silence = getattr(exc_value, "silence_logging", False) # Because the same exception may travel through this method more than # once (if it's re-raised) we may want to treat it differently # the second time (e.g. no user messages/logging). handled = issubclass(exc_type, HandledException) wrap = False # Restore our original exception information, but re-wrap it at the end if handled: exc_type, exc_value, exc_traceback = exc_value.wrapped wrap = True log_entry = encoding.force_text(exc_value) user_message = "" # We trust messages from our own exceptions if issubclass(exc_type, HorizonException): user_message = log_entry # If the message has a placeholder for the exception, fill it in elif message and "%(exc)s" in message: user_message = encoding.force_text(message) % {"exc": log_entry} elif message: user_message = encoding.force_text(message) for exc_handler in HANDLE_EXC_METHODS: if issubclass(exc_type, exc_handler['exc']): if exc_handler['set_wrap']: wrap = True handler = exc_handler['handler'] ret = handler(request, user_message, redirect, ignore, exc_handler.get('escalate', escalate), handled, force_silence, force_log, log_method, log_entry, log_level) if ret: return ret # return to normal code flow # If we've gotten here, time to wrap and/or raise our exception. if wrap: raise HandledException([exc_type, exc_value, exc_traceback]) # assume exceptions handled in the code that pass in a message are already # handled appropriately and treat as recoverable if message: ret = handle_recoverable(request, user_message, redirect, ignore, escalate, handled, force_silence, force_log, log_method, log_entry, log_level) if ret: return ret six.reraise(exc_type, exc_value, exc_traceback)