352 lines
12 KiB
Python
352 lines
12 KiB
Python
# Copyright 2012 Nebula, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""
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Exceptions raised by the Horizon code and the machinery for handling them.
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"""
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import logging
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import os
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import sys
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import six
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from django.core.management import color_style
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from django.utils import encoding
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from django.utils.translation import ugettext_lazy as _
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from django.views.debug import SafeExceptionReporterFilter
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from horizon.conf import HORIZON_CONFIG
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from horizon import messages
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LOG = logging.getLogger(__name__)
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class HorizonReporterFilter(SafeExceptionReporterFilter):
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"""Error report filter that's always active, even in DEBUG mode."""
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def is_active(self, request):
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return True
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class HorizonException(Exception):
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"""Base exception class for distinguishing our own exception classes."""
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pass
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class Http302(HorizonException):
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"""Exception used to redirect at the middleware level.
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This error class which can be raised from within a handler to cause
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an early bailout and redirect at the middleware level.
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"""
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status_code = 302
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def __init__(self, location, message=None):
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self.location = location
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self.message = message
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class NotAuthorized(HorizonException):
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"""User tries to access a resource without sufficient permissions.
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Raised whenever a user attempts to access a resource which they do not
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have permission-based access to (such as when failing the
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:func:`~horizon.decorators.require_perms` decorator).
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The included :class:`~horizon.middleware.HorizonMiddleware` catches
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``NotAuthorized`` and handles it gracefully by displaying an error
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message and redirecting the user to a login page.
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"""
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status_code = 401
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class NotAuthenticated(HorizonException):
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"""Raised when a user is trying to make requests and they are not logged in.
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The included :class:`~horizon.middleware.HorizonMiddleware` catches
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``NotAuthenticated`` and handles it gracefully by displaying an error
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message and redirecting the user to a login page.
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"""
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status_code = 403
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class NotFound(HorizonException):
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"""Generic error to replace all "Not Found"-type API errors."""
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status_code = 404
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class Conflict(HorizonException):
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"""Generic error to replace all "Conflict"-type API errors."""
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status_code = 409
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class BadRequest(HorizonException):
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"""Generic error to replace all "BadRequest"-type API errors."""
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status_code = 400
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class RecoverableError(HorizonException):
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"""Generic error to replace any "Recoverable"-type API errors."""
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status_code = 100 # HTTP status code "Continue"
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class ServiceCatalogException(HorizonException):
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"""A requested service is not available in the ``ServiceCatalog``.
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``ServiceCatalog`` is fetched from Keystone.
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"""
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def __init__(self, service_name):
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message = 'Invalid service catalog service: %s' % service_name
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super(ServiceCatalogException, self).__init__(message)
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@six.python_2_unicode_compatible
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class AlreadyExists(HorizonException):
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"""API resources tried to create already exists."""
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def __init__(self, name, resource_type):
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self.attrs = {"name": name, "resource": resource_type}
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self.msg = _('A %(resource)s with the name "%(name)s" already exists.')
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def __repr__(self):
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return self.msg % self.attrs
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def __str__(self):
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return self.msg % self.attrs
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@six.python_2_unicode_compatible
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class GetFileError(HorizonException):
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"""Exception to be raised when the value of get_file is not expected.
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The expected values start with https:// or http://.
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Otherwise this exception will be raised.
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"""
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def __init__(self, name, resource_type):
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self.attrs = {"name": name, "resource": resource_type}
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self.msg = _('The value of %(resource)s is %(name)s inside the '
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'template. When launching a stack from this interface,'
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' the value must start with "http://" or "https://"')
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def __repr__(self):
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return '<%s name=%r resource_type=%r>' % (self.__class__.__name__,
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self.attrs['name'],
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self.attrs['resource_type'])
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def __str__(self):
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return self.msg % self.attrs
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class ConfigurationError(HorizonException):
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"""Exception to be raised when invalid settings have been provided."""
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pass
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class NotAvailable(HorizonException):
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"""Exception to be raised when something is not available."""
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pass
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class WorkflowError(HorizonException):
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"""Exception to be raised when something goes wrong in a workflow."""
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pass
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class WorkflowValidationError(HorizonException):
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"""Exception raised during workflow validation.
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It is raised if required data is missing,
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or existing data is not valid.
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"""
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pass
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class MessageFailure(HorizonException):
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"""Exception raised during message notification."""
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pass
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class HandledException(HorizonException):
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"""Used internally to track exceptions that are already handled.
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It is used to track exceptions that have gone through
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:func:`horizon.exceptions.handle` more than once.
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"""
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def __init__(self, wrapped):
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self.wrapped = wrapped
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UNAUTHORIZED = tuple(HORIZON_CONFIG['exceptions']['unauthorized'])
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UNAUTHORIZED += (NotAuthorized,)
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NOT_FOUND = tuple(HORIZON_CONFIG['exceptions']['not_found'])
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NOT_FOUND += (GetFileError,)
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RECOVERABLE = (AlreadyExists, Conflict, NotAvailable, ServiceCatalogException,
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BadRequest)
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RECOVERABLE += tuple(HORIZON_CONFIG['exceptions']['recoverable'])
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def error_color(msg):
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return color_style().ERROR_OUTPUT(msg)
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def check_message(keywords, message):
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"""Checks an exception for given keywords and raises an error if found.
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It raises a new ``ActionError`` with the desired message if the
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keywords are found. This allows selective
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control over API error messages.
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"""
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exc_type, exc_value, exc_traceback = sys.exc_info()
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if set(str(exc_value).split(" ")).issuperset(set(keywords)):
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exc_value.message = message
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raise
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def handle_unauthorized(request, message, redirect, ignore, escalate, handled,
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force_silence, force_log,
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log_method, log_entry, log_level):
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if ignore:
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return NotAuthorized
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if not force_silence and not handled:
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log_method(error_color("Unauthorized: %s" % log_entry))
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if not handled:
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if message:
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message = _("Unauthorized: %s") % message
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# We get some pretty useless error messages back from
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# some clients, so let's define our own fallback.
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fallback = _("Unauthorized. Please try logging in again.")
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messages.error(request, message or fallback)
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# Continue and present our "unauthorized" error message.
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raise NotAuthorized
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def handle_notfound(request, message, redirect, ignore, escalate, handled,
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force_silence, force_log,
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log_method, log_entry, log_level):
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if not force_silence and not handled and (not ignore or force_log):
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log_method(error_color("Not Found: %s" % log_entry))
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if not ignore and not handled:
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messages.error(request, message or log_entry)
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if redirect:
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raise Http302(redirect)
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if not escalate:
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return NotFound # return to normal code flow
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def handle_recoverable(request, message, redirect, ignore, escalate, handled,
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force_silence, force_log,
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log_method, log_entry, log_level):
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if not force_silence and not handled and (not ignore or force_log):
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# Default recoverable error to WARN log level
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log_method = getattr(LOG, log_level or "warning")
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log_method(error_color("Recoverable error: %s" % log_entry))
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if not ignore and not handled:
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messages.error(request, message or log_entry)
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if redirect:
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raise Http302(redirect)
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if not escalate:
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return RecoverableError # return to normal code flow
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HANDLE_EXC_METHODS = [
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{'exc': UNAUTHORIZED, 'handler': handle_unauthorized,
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'set_wrap': False, 'escalate': True},
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{'exc': NOT_FOUND, 'handler': handle_notfound, 'set_wrap': True},
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{'exc': RECOVERABLE, 'handler': handle_recoverable, 'set_wrap': True},
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]
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def handle(request, message=None, redirect=None, ignore=False,
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escalate=False, log_level=None, force_log=None):
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"""Centralized error handling for Horizon.
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Because Horizon consumes so many different APIs with completely
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different ``Exception`` types, it's necessary to have a centralized
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place for handling exceptions which may be raised.
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Exceptions are roughly divided into 3 types:
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#. ``UNAUTHORIZED``: Errors resulting from authentication or authorization
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problems. These result in being logged out and sent to the login screen.
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#. ``NOT_FOUND``: Errors resulting from objects which could not be
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located via the API. These generally result in a user-facing error
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message, but are otherwise returned to the normal code flow. Optionally
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a redirect value may be passed to the error handler so users are
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returned to a different view than the one requested in addition to the
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error message.
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#. ``RECOVERABLE``: Generic API errors which generate a user-facing message
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but drop directly back to the regular code flow.
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All other exceptions bubble the stack as normal unless the ``ignore``
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argument is passed in as ``True``, in which case only unrecognized
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errors are bubbled.
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If the exception is not re-raised, an appropriate wrapper exception
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class indicating the type of exception that was encountered will be
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returned.
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"""
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exc_type, exc_value, exc_traceback = sys.exc_info()
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log_method = getattr(LOG, log_level or "exception")
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force_log = force_log or os.environ.get("HORIZON_TEST_RUN", False)
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force_silence = getattr(exc_value, "silence_logging", False)
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# Because the same exception may travel through this method more than
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# once (if it's re-raised) we may want to treat it differently
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# the second time (e.g. no user messages/logging).
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handled = issubclass(exc_type, HandledException)
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wrap = False
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# Restore our original exception information, but re-wrap it at the end
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if handled:
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exc_type, exc_value, exc_traceback = exc_value.wrapped
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wrap = True
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log_entry = encoding.force_text(exc_value)
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user_message = ""
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# We trust messages from our own exceptions
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if issubclass(exc_type, HorizonException):
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user_message = log_entry
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# If the message has a placeholder for the exception, fill it in
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elif message and "%(exc)s" in message:
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user_message = encoding.force_text(message) % {"exc": log_entry}
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elif message:
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user_message = encoding.force_text(message)
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for exc_handler in HANDLE_EXC_METHODS:
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if issubclass(exc_type, exc_handler['exc']):
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if exc_handler['set_wrap']:
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wrap = True
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handler = exc_handler['handler']
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ret = handler(request, user_message, redirect, ignore,
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exc_handler.get('escalate', escalate),
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handled, force_silence, force_log,
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log_method, log_entry, log_level)
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if ret:
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return ret # return to normal code flow
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# If we've gotten here, time to wrap and/or raise our exception.
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if wrap:
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raise HandledException([exc_type, exc_value, exc_traceback])
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# assume exceptions handled in the code that pass in a message are already
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# handled appropriately and treat as recoverable
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if message:
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ret = handle_recoverable(request, user_message, redirect, ignore,
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escalate, handled, force_silence, force_log,
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log_method, log_entry, log_level)
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if ret:
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return ret
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six.reraise(exc_type, exc_value, exc_traceback)
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