Source code for heat.engine.update
#
# 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 copy
from heat.db import api as db_api
from heat.engine import dependencies
from heat.engine import resource
from heat.engine import scheduler
from heat.openstack.common.gettextutils import _
from heat.openstack.common import log as logging
logger = logging.getLogger(__name__)
[docs]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.parsed_template())
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)
update = scheduler.DependencyTaskGroup(self.dependencies(),
self._resource_update)
if not self.rollback:
yield cleanup_prev()
try:
yield update()
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)):
logger.debug(_("Deleting backup resource %s") % prev_res.name)
yield prev_res.destroy()
@staticmethod
def _exchange_stacks(existing_res, prev_res):
db_api.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[existing_res.name] = existing_res
existing_stack[prev_res.name] = 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:
logger.debug(_("Swapping in backup Resource %s") %
res_name)
self._exchange_stacks(self.existing_stack[res_name],
prev_res)
return
logger.debug(_("Deleting backup Resource %s") % res_name)
yield prev_res.destroy()
# Back up existing resource
if res_name in self.existing_stack:
logger.debug(_("Backing up existing Resource %s") % res_name)
existing_res = self.existing_stack[res_name]
self.previous_stack[res_name] = existing_res
existing_res.state_set(existing_res.UPDATE, existing_res.COMPLETE)
self.existing_stack[res_name] = new_res
yield new_res.create()
@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]
try:
yield self._update_in_place(existing_res,
new_res)
except resource.UpdateReplace:
pass
else:
logger.info(_("Resource %(res_name)s for stack %(stack_name)s"
" updated") % {
'res_name': res_name,
'stack_name': self.existing_stack.name})
return
yield self._create_resource(new_res)
def _update_in_place(self, existing_res, new_res):
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)
raw_snippet = copy.deepcopy(new_res.t)
parsed_snippet = self.existing_stack.resolve_static_data(raw_snippet)
new_snippet = self.existing_stack.resolve_runtime_data(parsed_snippet)
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:
del self.existing_stack[res_name]
[docs] def dependencies(self):
'''
Return 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 self.existing_stack.iteritems():
if name in self.new_stack:
yield (res, self.new_stack[name])
return dependencies.Dependencies(edges())