# Copyright 2014 Budapest University of Technology and Economics (BME IK)
#
# This file is part of CIRCLE Cloud.
#
# CIRCLE is free software: you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free
# Software Foundation, either version 3 of the License, or (at your option)
# any later version.
#
# CIRCLE is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
# details.
#
# You should have received a copy of the GNU General Public License along
# with CIRCLE. If not, see <http://www.gnu.org/licenses/>.
from inspect import getargspec
from logging import getLogger
from django.core.exceptions import PermissionDenied, ImproperlyConfigured
from django.utils.translation import ugettext_noop
from .models import (activity_context, has_suffix, humanize_exception,
HumanReadableObject)
logger = getLogger(__name__)
class Operation(object):
"""Base class for VM operations.
"""
required_perms = None
superuser_required = False
do_not_call_in_templates = True
abortable = False
has_percentage = False
def __call__(self, **kwargs):
return self.call(**kwargs)
def __init__(self, subject):
"""Initialize a new operation bound to the specified subject.
"""
self.subject = subject
def __unicode__(self):
return self.name
def __prelude(self, request, kwargs):
"""This method contains the shared prelude of call and async.
"""
defaults = {'system': False, 'user': None}
allargs = dict(defaults, **kwargs) # all arguments
auxargs = allargs.copy() # auxiliary (i.e. only for _operation) args
# NOTE: consumed items should be removed from auxargs, and no new items
# should be added to it
skip_auth_check = auxargs.pop('system')
user = auxargs.pop('user')
if user is None: # parent was a system call
skip_auth_check = True
# check for unexpected keyword arguments
argspec = getargspec(self._operation)
if argspec.keywords is None: # _operation doesn't take ** args
unexpected_kwargs = set(auxargs) - set(argspec.args)
if unexpected_kwargs:
raise TypeError("Operation got unexpected keyword arguments: "
"%s" % ", ".join(unexpected_kwargs))
if not skip_auth_check:
self.check_auth(user, request)
self.check_precond()
return allargs, auxargs
def _exec_op(self, request, allargs, auxargs):
"""Execute the operation inside the specified activity's context.
"""
# compile arguments for _operation
argspec = getargspec(self._operation)
if argspec.keywords is not None: # _operation takes ** args
arguments = allargs.copy()
else: # _operation doesn't take ** args
arguments = {k: v for (k, v) in allargs.iteritems()
if k in argspec.args}
arguments.update(auxargs)
return self._operation(request, **arguments)
def _operation(self, **kwargs):
"""This method is the operation's particular implementation.
Deriving classes should implement this method.
"""
raise NotImplementedError
def call(self, request, **kwargs):
"""Execute the operation (synchronously).
Anticipated keyword arguments:
* parent_activity: Parent activity for the operation. If this argument
is present, the operation's activity will be created
as a child activity of it.
* system: Indicates that the operation is invoked by the system, not a
User. If this argument is present and has a value of True,
then authorization checks are skipped.
* user: The User invoking the operation. If this argument is not
present, it'll be provided with a default value of None.
"""
allargs, auxargs = self.__prelude(request, kwargs)
logger.info("%s called (synchronously) on %s with the following "
"parameters: %r", self.__class__.__name__, self.subject,
kwargs)
return self._exec_op(request, allargs, auxargs)
def check_precond(self):
pass
@classmethod
def check_perms(cls, user):
"""Check if user is permitted to run this operation on any instance
"""
if cls.required_perms is None:
raise ImproperlyConfigured(
"Set required_perms to () if none needed.")
if not user.has_perms(cls.required_perms):
raise humanize_exception(ugettext_noop(
"You don't have the required permissions."),
PermissionDenied())
if cls.superuser_required and not user.is_superuser:
raise humanize_exception(ugettext_noop(
"Superuser privileges are required."), PermissionDenied())
def check_auth(self, user):
"""Check if user is permitted to run this operation on this instance
"""
#TODO: implement
pass
def on_abort(self, activity, error):
"""This method is called when the operation aborts (i.e. raises an
exception).
"""
pass
def on_commit(self, activity):
"""This method is called when the operation executes successfully.
"""
pass
operation_registry_name = '_ops'
class OperatedMixin(object):
def __getattr__(self, name):
# NOTE: __getattr__ is only called if the attribute doesn't already
# exist in your __dict__
return self.get_operation_class(name)(self)
@classmethod
def get_operation_class(cls, name):
ops = getattr(cls, operation_registry_name, {})
op = ops.get(name)
if op:
return op
else:
raise AttributeError("%r object has no attribute %r" %
(cls.__name__, name))
def get_available_operations(self, user):
"""Yield Operations that match permissions of user and preconditions.
"""
for name in getattr(self, operation_registry_name, {}):
op = getattr(self, name)
try:
op.check_auth(user)
op.check_precond()
except:
pass # unavailable
else:
yield op
def get_operation_from_activity_code(self, activity_code):
"""Get an instance of the Operation corresponding to the specified
activity code.
:returns: A bound instance of an operation, or None if no matching
operation could be found.
"""
for op in getattr(self, operation_registry_name, {}).itervalues():
if has_suffix(activity_code, op.get_activity_code_suffix()):
return op(self)
else:
return None
def register_operation(op_cls, op_id=None, target_cls=None):
"""Register the specified operation with the target class.
You can optionally specify an ID to be used for the registration;
otherwise, the operation class' 'id' attribute will be used.
"""
if op_id is None:
try:
op_id = op_cls.id
except AttributeError:
raise NotImplementedError("Operations should specify an 'id' "
"attribute designating the name the "
"operation can be called by on its "
"host. Alternatively, provide the name "
"in the 'op_id' parameter to this call.")
if target_cls is None:
try:
target_cls = op_cls.host_cls
except AttributeError:
raise NotImplementedError("Operations should specify a 'host_cls' "
"attribute designating the host class "
"the operation should be registered to. "
"Alternatively, provide the host class "
"in the 'target_cls' parameter to this "
"call.")
assert not hasattr(target_cls, op_id), (
"target class already has an attribute with this id")
if not hasattr(target_cls, operation_registry_name):
setattr(target_cls, operation_registry_name, dict())
getattr(target_cls, operation_registry_name)[op_id] = op_cls
def get_operation_class(cls, name):
ops = getattr(cls, operation_registry_name, {})
op = ops.get(name)
if op:
return op
else:
raise AttributeError("%r object has no attribute %r" %
(cls.__name__, name))
def __getattr__(self, name):
# NOTE: __getattr__ is only called if the attribute doesn't already
# exist in your __dict__
return get_operation_class(type(self), name)(self)
target_cls.__getattr__ = __getattr__
return op_cls