196 lines
7.4 KiB
Python
196 lines
7.4 KiB
Python
#
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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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import copy
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from heat.db import api as db_api
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from heat.engine import dependencies
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from heat.engine import resource
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from heat.engine import scheduler
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from heat.openstack.common.gettextutils import _
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from heat.openstack.common import log as logging
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logger = logging.getLogger(__name__)
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class StackUpdate(object):
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"""
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A Task to perform the update of an existing stack to a new template.
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"""
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def __init__(self, existing_stack, new_stack, previous_stack,
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rollback=False):
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"""Initialise with the existing stack and the new stack."""
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self.existing_stack = existing_stack
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self.new_stack = new_stack
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self.previous_stack = previous_stack
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self.rollback = rollback
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self.existing_snippets = dict((n, r.parsed_template())
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for n, r in self.existing_stack.items())
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def __repr__(self):
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if self.rollback:
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return '%s Rollback' % str(self.existing_stack)
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else:
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return '%s Update' % str(self.existing_stack)
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@scheduler.wrappertask
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def __call__(self):
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"""Return a co-routine that updates the stack."""
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cleanup_prev = scheduler.DependencyTaskGroup(
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self.previous_stack.dependencies,
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self._remove_backup_resource,
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reverse=True)
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update = scheduler.DependencyTaskGroup(self.dependencies(),
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self._resource_update)
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if not self.rollback:
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yield cleanup_prev()
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try:
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yield update()
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finally:
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self.previous_stack.reset_dependencies()
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def _resource_update(self, res):
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if res.name in self.new_stack and self.new_stack[res.name] is res:
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return self._process_new_resource_update(res)
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else:
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return self._process_existing_resource_update(res)
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@scheduler.wrappertask
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def _remove_backup_resource(self, prev_res):
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if prev_res.state not in ((prev_res.INIT, prev_res.COMPLETE),
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(prev_res.DELETE, prev_res.COMPLETE)):
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logger.debug(_("Deleting backup resource %s") % prev_res.name)
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yield prev_res.destroy()
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@staticmethod
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def _exchange_stacks(existing_res, prev_res):
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db_api.resource_exchange_stacks(existing_res.stack.context,
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existing_res.id, prev_res.id)
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prev_stack, existing_stack = prev_res.stack, existing_res.stack
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prev_stack[existing_res.name] = existing_res
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existing_stack[prev_res.name] = prev_res
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@scheduler.wrappertask
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def _create_resource(self, new_res):
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res_name = new_res.name
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# Clean up previous resource
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if res_name in self.previous_stack:
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prev_res = self.previous_stack[res_name]
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if prev_res.state not in ((prev_res.INIT, prev_res.COMPLETE),
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(prev_res.DELETE, prev_res.COMPLETE)):
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# Swap in the backup resource if it is in a valid state,
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# instead of creating a new resource
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if prev_res.status == prev_res.COMPLETE:
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logger.debug(_("Swapping in backup Resource %s") %
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res_name)
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self._exchange_stacks(self.existing_stack[res_name],
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prev_res)
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return
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logger.debug(_("Deleting backup Resource %s") % res_name)
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yield prev_res.destroy()
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# Back up existing resource
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if res_name in self.existing_stack:
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logger.debug(_("Backing up existing Resource %s") % res_name)
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existing_res = self.existing_stack[res_name]
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self.previous_stack[res_name] = existing_res
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existing_res.state_set(existing_res.UPDATE, existing_res.COMPLETE)
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self.existing_stack[res_name] = new_res
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yield new_res.create()
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@scheduler.wrappertask
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def _process_new_resource_update(self, new_res):
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res_name = new_res.name
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if res_name in self.existing_stack:
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existing_res = self.existing_stack[res_name]
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try:
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yield self._update_in_place(existing_res,
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new_res)
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except resource.UpdateReplace:
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pass
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else:
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logger.info(_("Resource %(res_name)s for stack %(stack_name)s"
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" updated") % {
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'res_name': res_name,
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'stack_name': self.existing_stack.name})
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return
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yield self._create_resource(new_res)
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def _update_in_place(self, existing_res, new_res):
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existing_snippet = self.existing_snippets[existing_res.name]
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prev_res = self.previous_stack.get(new_res.name)
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# Note the new resource snippet is resolved in the context
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# of the existing stack (which is the stack being updated)
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raw_snippet = copy.deepcopy(new_res.t)
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parsed_snippet = self.existing_stack.resolve_static_data(raw_snippet)
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new_snippet = self.existing_stack.resolve_runtime_data(parsed_snippet)
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return existing_res.update(new_snippet, existing_snippet,
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prev_resource=prev_res)
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@scheduler.wrappertask
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def _process_existing_resource_update(self, existing_res):
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res_name = existing_res.name
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if res_name in self.previous_stack:
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yield self._remove_backup_resource(self.previous_stack[res_name])
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if res_name in self.new_stack:
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new_res = self.new_stack[res_name]
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if new_res.state == (new_res.INIT, new_res.COMPLETE):
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# Already updated in-place
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return
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if existing_res.stack is not self.previous_stack:
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yield existing_res.destroy()
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if res_name not in self.new_stack:
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del self.existing_stack[res_name]
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def dependencies(self):
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'''
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Return a Dependencies object representing the dependencies between
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update operations to move from an existing stack definition to a new
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one.
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'''
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existing_deps = self.existing_stack.dependencies
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new_deps = self.new_stack.dependencies
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def edges():
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# Create/update the new stack's resources in create order
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for e in new_deps.graph().edges():
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yield e
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# Destroy/cleanup the old stack's resources in delete order
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for e in existing_deps.graph(reverse=True).edges():
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yield e
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# Don't cleanup old resources until after they have been replaced
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for name, res in self.existing_stack.iteritems():
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if name in self.new_stack:
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yield (res, self.new_stack[name])
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return dependencies.Dependencies(edges())
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