update fails for nested stack

[Removed by request]

A stack has failed creation due to an issue with a nested template. After trying stack-update to try and fix it, the update failed with "stack not created"

Steps to reproduce:
   1. nova keypair-add keypair_heat
   2. Using below templates, run heat stack-create test-001 -f test_fail.yaml
   3. nova keypair-delete keypair_heat
   4. heat stack-update with the same template

Heat starts the updating progress but fails because 'Error: Cannot update server, stack not created'. If this is as designed, then it should be picked at validation, and update should not start.

== log: ==

2015-01-15 06:28:53.476 2364 INFO heat.engine.resource [-] UPDATE: TemplateResource "server" Stack "test-002" [11780e9b-0e19-4764-a6c1-a1b40527ed98]
2015-01-15 06:28:53.476 2364 TRACE heat.engine.resource Traceback (most recent call last):
2015-01-15 06:28:53.476 2364 TRACE heat.engine.resource File "/usr/lib/python2.7/site-packages/heat/engine/resource.py", line 435, in _action_recorder
2015-01-15 06:28:53.476 2364 TRACE heat.engine.resource yield
2015-01-15 06:28:53.476 2364 TRACE heat.engine.resource File "/usr/lib/python2.7/site-packages/heat/engine/resource.py", line 690, in update
2015-01-15 06:28:53.476 2364 TRACE heat.engine.resource args=[after, tmpl_diff, prop_diff])
2015-01-15 06:28:53.476 2364 TRACE heat.engine.resource File "/usr/lib/python2.7/site-packages/heat/engine/scheduler.py", line 286, in wrapper
2015-01-15 06:28:53.476 2364 TRACE heat.engine.resource step = next(subtask)
2015-01-15 06:28:53.476 2364 TRACE heat.engine.resource File "/usr/lib/python2.7/site-packages/heat/engine/resource.py", line 476, in action_handler_task
2015-01-15 06:28:53.476 2364 TRACE heat.engine.resource handler_data = handler(*args)
2015-01-15 06:28:53.476 2364 TRACE heat.engine.resource File "/usr/lib/python2.7/site-packages/heat/engine/resources/template_resource.py", line 256, in handle_update
2015-01-15 06:28:53.476 2364 TRACE heat.engine.resource self.child_params())
2015-01-15 06:28:53.476 2364 TRACE heat.engine.resource File "/usr/lib/python2.7/site-packages/heat/engine/stack_resource.py", line 227, in update_with_template
2015-01-15 06:28:53.476 2364 TRACE heat.engine.resource % self.name)
2015-01-15 06:28:53.476 2364 TRACE heat.engine.resource Error: Cannot update server, stack not created
2015-01-15 06:28:53.476 2364 TRACE heat.engine.resource

== templates: ==

test_fail.yaml:

heat_template_version: 2013-05-23

parameters:

  flavor:
    type: string
    default: m1.tiny

resources:

  keypair:
    type: OS::Nova::KeyPair
    properties:
      name: keypair_heat
      save_private_key: false

  server:
    type: server_fail.yaml
    properties:
      flavor: {get_param: flavor}
      key_name: {get_resource: keypair}
    depends_on: keypair

server_fail.yaml:

heat_template_version: 2013-05-23

parameters:
  image:
    type: string
    default: cirros-0.3.3-x86_64-disk
  key_name:
    type: string
  flavor:
    type: string
  availability_zone:
    type: string
    default: nova

resources:
  server:
    type: OS::Nova::Server
    properties:
      availability_zone: { get_param: availability_zone }
      flavor: { get_param: flavor }
      image: { get_param: image }
      key_name: { get_param: key_name }

[Removed by request (removed3381998)]

Heat version is from Sat Jan 10 14:19:40 2015 (commit 15043074b1cc92e720a570936b761706dcd86c58) on a devstack environment

[Song Li (lisong-cruise)]

I think there would be a lots of problems like this one.
Maybe we might need a blue print to implement a precheck.

[Angus Salkeld (asalkeld)]

Song Li, please not a blueprint for a bug fix.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/147463

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/147463
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=aafbf6025ca826d76f5ea6e99dfe2c2e62fe0422
Submitter: Jenkins
Branch: master

commit aafbf6025ca826d76f5ea6e99dfe2c2e62fe0422
Author: Angus Salkeld <email address hidden>
Date: Tue Feb 3 15:31:47 2015 +1000

    Fix update on failed stack

    In the case of a dependant resource failing, a nested stack will not get
    created, so we need to at least create an empty nested stack to allow
    the update to work.

    Change-Id: I2e83546801bce0da566ec8ef1322e30d695ff02a
    Closes-bug: 1411103

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/juno
Review: https://review.openstack.org/153368

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/153368
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=f6dfcc23de9e5d71988cc1de915198688a2d7c2f
Submitter: Jenkins
Branch: stable/juno

commit f6dfcc23de9e5d71988cc1de915198688a2d7c2f
Author: Angus Salkeld <email address hidden>
Date: Tue Feb 3 15:31:47 2015 +1000

    Fix update on failed stack

    In the case of a dependant resource failing, a nested stack will not get
    created, so we need to at least create an empty nested stack to allow
    the update to work.

    Change-Id: I2e83546801bce0da566ec8ef1322e30d695ff02a
    Closes-bug: 1411103
    (cherry picked from commit aafbf6025ca826d76f5ea6e99dfe2c2e62fe0422)