deb-heat/heat/engine/update.py
Zane Bitter 7b129f666f Copy correct definition to the backup stack
We were using the definition of the existing resource, immediately after
updating it in place, to copy to the backup stack. This turns out to be
incorrect, because the definition of the new resource is only copied to the
existing resource if it was actually updated. It doesn't follow that the
existing resource's definition must be the same, because it's actually the
frozen definition (using the stored property values from the DB) that's
compared with the new definition when deciding to update. The existing
definition might well be rubbish if a previous update is failed, because it
does not get updated in the existing template after the resource is updated
in place. This caused bug 1622795 when combined with the new conditionals
feature.

We were also using the wrong template to do the parsing in both cases: when
updating in-place we are passing the new definition, but we were reparsing
using the existing template. And we were effectively doing the same when
creating a new resource, because we accessed the template through the new
resource only *after* it had been moved to the existing stack. In both
cases the correct code would have been:

  definition = new_res.t.reparse(self.previous_stack,
                                 new_res.stack.t)

However, there's no actual need to reparse the resource definitions before
passing them to Template.add_resource(), because that method immediately
calls render_hot() to get back to the unparsed definition anyway. So just
don't bother. These issues have been requiring us up until now to cache the
conditionals from the new_stack in the Template, to prevent the reparsing
from looking at the wrong set of conditionals. This change relieves us of
that restriction.

Finally, change the debug error messages to distinguish this case (copying
a resource definition into the backup template) from "backing up" a
resource (moving an actual physical resource into the backup stack).

Change-Id: I7be92f2e1b812c23fa52d87c18c7f22f1be94446
Closes-Bug: #1622795
2016-09-12 20:51:52 -04:00

287 lines
12 KiB
Python

#
# 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.
from oslo_log import log as logging
import six
from heat.common import exception
from heat.common.i18n import _LI
from heat.common.i18n import repr_wrapper
from heat.engine import dependencies
from heat.engine import resource
from heat.engine import scheduler
from heat.objects import resource as resource_objects
LOG = logging.getLogger(__name__)
@repr_wrapper
class StackUpdate(object):
"""A Task to perform the update of an existing stack to a new template."""
def __init__(self, existing_stack, new_stack, previous_stack,
rollback=False):
"""Initialise with the existing stack and the new stack."""
self.existing_stack = existing_stack
self.new_stack = new_stack
self.previous_stack = previous_stack
self.rollback = rollback
self.existing_snippets = dict((n, r.frozen_definition())
for n, r in self.existing_stack.items())
def __repr__(self):
if self.rollback:
return '%s Rollback' % str(self.existing_stack)
else:
return '%s Update' % str(self.existing_stack)
@scheduler.wrappertask
def __call__(self):
"""Return a co-routine that updates the stack."""
cleanup_prev = scheduler.DependencyTaskGroup(
self.previous_stack.dependencies,
self._remove_backup_resource,
reverse=True)
def get_error_wait_time(resource):
return resource.cancel_grace_period()
updater = scheduler.DependencyTaskGroup(
self.dependencies(),
self._resource_update,
error_wait_time=get_error_wait_time)
if not self.rollback:
yield cleanup_prev()
try:
yield updater()
finally:
self.previous_stack.reset_dependencies()
def _resource_update(self, res):
if res.name in self.new_stack and self.new_stack[res.name] is res:
return self._process_new_resource_update(res)
else:
return self._process_existing_resource_update(res)
@scheduler.wrappertask
def _remove_backup_resource(self, prev_res):
if prev_res.state not in ((prev_res.INIT, prev_res.COMPLETE),
(prev_res.DELETE, prev_res.COMPLETE)):
LOG.debug("Deleting backup resource %s" % prev_res.name)
yield prev_res.destroy()
@staticmethod
def _exchange_stacks(existing_res, prev_res):
resource_objects.Resource.exchange_stacks(existing_res.stack.context,
existing_res.id, prev_res.id)
prev_stack, existing_stack = prev_res.stack, existing_res.stack
prev_stack.add_resource(existing_res)
existing_stack.add_resource(prev_res)
@scheduler.wrappertask
def _create_resource(self, new_res):
res_name = new_res.name
# Clean up previous resource
if res_name in self.previous_stack:
prev_res = self.previous_stack[res_name]
if prev_res.state not in ((prev_res.INIT, prev_res.COMPLETE),
(prev_res.DELETE, prev_res.COMPLETE)):
# Swap in the backup resource if it is in a valid state,
# instead of creating a new resource
if prev_res.status == prev_res.COMPLETE:
LOG.debug("Swapping in backup Resource %s" % res_name)
self._exchange_stacks(self.existing_stack[res_name],
prev_res)
return
LOG.debug("Deleting backup Resource %s" % res_name)
yield prev_res.destroy()
# Back up existing resource
if res_name in self.existing_stack:
LOG.debug("Backing up existing Resource %s" % res_name)
existing_res = self.existing_stack[res_name]
self.previous_stack.add_resource(existing_res)
existing_res.state_set(existing_res.UPDATE, existing_res.COMPLETE)
self.existing_stack.add_resource(new_res)
# Save new resource definition to backup stack if it is not
# present in backup stack template already
# it allows to resolve all dependencies that existing resource
# can have if it was copied to backup stack
if (res_name not in
self.previous_stack.t[self.previous_stack.t.RESOURCES]):
LOG.debug("Storing definition of new Resource %s", res_name)
self.previous_stack.t.add_resource(new_res.t)
self.previous_stack.t.store(self.previous_stack.context)
yield new_res.create()
def _check_replace_restricted(self, res):
registry = res.stack.env.registry
restricted_actions = registry.get_rsrc_restricted_actions(res.name)
existing_res = self.existing_stack[res.name]
if 'replace' in restricted_actions:
ex = exception.ResourceActionRestricted(action='replace')
failure = exception.ResourceFailure(ex, existing_res,
existing_res.UPDATE)
existing_res._add_event(existing_res.UPDATE, existing_res.FAILED,
six.text_type(ex))
raise failure
@scheduler.wrappertask
def _process_new_resource_update(self, new_res):
res_name = new_res.name
if res_name in self.existing_stack:
existing_res = self.existing_stack[res_name]
is_substituted = existing_res.check_is_substituted(type(new_res))
if type(existing_res) is type(new_res) or is_substituted:
try:
yield self._update_in_place(existing_res,
new_res,
is_substituted)
except resource.UpdateReplace:
pass
else:
# Save updated resource definition to backup stack
# cause it allows the backup stack resources to be
# synchronized
LOG.debug("Storing definition of updated Resource %s",
res_name)
self.previous_stack.t.add_resource(new_res.t)
self.previous_stack.t.store(self.previous_stack.context)
LOG.info(_LI("Resource %(res_name)s for stack "
"%(stack_name)s updated"),
{'res_name': res_name,
'stack_name': self.existing_stack.name})
return
else:
self._check_replace_restricted(new_res)
yield self._create_resource(new_res)
def _update_in_place(self, existing_res, new_res, is_substituted=False):
existing_snippet = self.existing_snippets[existing_res.name]
prev_res = self.previous_stack.get(new_res.name)
# Note the new resource snippet is resolved in the context
# of the existing stack (which is the stack being updated)
# but with the template of the new stack (in case the update
# is switching template implementations)
new_snippet = new_res.t.reparse(self.existing_stack,
self.new_stack.t)
if is_substituted:
substitute = type(new_res)(existing_res.name,
existing_res.t,
existing_res.stack)
existing_res.stack.resources[existing_res.name] = substitute
existing_res = substitute
return existing_res.update(new_snippet, existing_snippet,
prev_resource=prev_res)
@scheduler.wrappertask
def _process_existing_resource_update(self, existing_res):
res_name = existing_res.name
if res_name in self.previous_stack:
yield self._remove_backup_resource(self.previous_stack[res_name])
if res_name in self.new_stack:
new_res = self.new_stack[res_name]
if new_res.state == (new_res.INIT, new_res.COMPLETE):
# Already updated in-place
return
if existing_res.stack is not self.previous_stack:
yield existing_res.destroy()
if res_name not in self.new_stack:
self.existing_stack.remove_resource(res_name)
def dependencies(self):
"""Return the Dependencies graph for the update.
Returns a Dependencies object representing the dependencies between
update operations to move from an existing stack definition to a new
one.
"""
existing_deps = self.existing_stack.dependencies
new_deps = self.new_stack.dependencies
def edges():
# Create/update the new stack's resources in create order
for e in new_deps.graph().edges():
yield e
# Destroy/cleanup the old stack's resources in delete order
for e in existing_deps.graph(reverse=True).edges():
yield e
# Don't cleanup old resources until after they have been replaced
for name, res in six.iteritems(self.existing_stack):
if name in self.new_stack:
yield (res, self.new_stack[name])
return dependencies.Dependencies(edges())
def preview(self):
upd_keys = set(self.new_stack.resources.keys())
cur_keys = set(self.existing_stack.resources.keys())
common_keys = cur_keys.intersection(upd_keys)
deleted_keys = cur_keys.difference(upd_keys)
added_keys = upd_keys.difference(cur_keys)
updated_keys = []
replaced_keys = []
for key in common_keys:
current_res = self.existing_stack.resources[key]
updated_res = self.new_stack.resources[key]
current_props = current_res.frozen_definition().properties(
current_res.properties_schema, current_res.context)
updated_props = updated_res.frozen_definition().properties(
updated_res.properties_schema, updated_res.context)
# type comparison must match that in _process_new_resource_update
if type(current_res) is not type(updated_res):
replaced_keys.append(key)
continue
try:
if current_res.preview_update(updated_res.frozen_definition(),
current_res.frozen_definition(),
updated_props, current_props,
None):
updated_keys.append(key)
except resource.UpdateReplace:
replaced_keys.append(key)
return {
'unchanged': list(set(common_keys).difference(
set(updated_keys + replaced_keys))),
'updated': updated_keys,
'replaced': replaced_keys,
'added': list(added_keys),
'deleted': list(deleted_keys),
}