Exceptions when adding implicit dependencies cause stacks to be unloadable

[Zane Bitter]

There have been a number of errors caused by the code to add implicit dependencies for a particular resource type (i.e. overriding Resource.add_dependencies() - something used heavily by Neutron resources) raising an exception. If this exception occurs in a non-deterministic way (e.g. it depends on external state) then we can get into a situation where a stack can be created but we cannot load it from the DB again to delete (or even show) it. Examples of this class of error include bug 1442121 and bug 1536515.

While we always need to fix plugins that are broken in this way, since it is a common programming error we also need to prevent plugins with this problem from breaking Heat and leaving stacks undeletable.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/290027

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/290027
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=38a46e8d21602e1ebed22c38ba53c0095c6be609
Submitter: Jenkins
Branch: master

commit 38a46e8d21602e1ebed22c38ba53c0095c6be609
Author: Zane Bitter <email address hidden>
Date: Tue Mar 8 11:35:12 2016 -0500

    Catch exceptions calculating implicit dependencies

    Uncaught exceptions in an overridden add_dependencies() method of a plugin
    can prevent a stack being loaded from the database. To protect against
    programming errors that can result in uncaught exceptions, separate the
    calculation of implicit dependencies out from the calculation of explicit
    dependencies, and ignore exceptions in the latter when dealing with an
    existing stack.

    Change-Id: I939dba57eeba5710bb77a1b30a872fca5d38ad71
    Closes-Bug: #1554625

[Thierry Carrez (ttx)]

This issue was fixed in the openstack/heat 6.0.0.0rc1 release candidate.

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.openstack.org/299184

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/299184
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=d263687f8469a3c7f7897484405c76b671f02fd6
Submitter: Jenkins
Branch: master

commit d263687f8469a3c7f7897484405c76b671f02fd6
Author: Johannes Grassler <email address hidden>
Date: Wed Mar 30 09:55:37 2016 +0200

    Warn against API calls in plugin guide

    API calls raising uncaught exceptions have previously caused problems,
    especially when deleting stacks or cleaning up after a stack's partial
    deletion. This commit explicitely documents this pitfall.

    Change-Id: If86ef0deb5b8eaa1a0665c07bfddcfe52994f249
    Related-Bug: #1554625

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/liberty
Review: https://review.openstack.org/333309

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/333309
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=3cb015e41015679af71c788b516c7de8280f3a30
Submitter: Jenkins
Branch: stable/liberty

commit 3cb015e41015679af71c788b516c7de8280f3a30
Author: Zane Bitter <email address hidden>
Date: Tue Mar 8 11:35:12 2016 -0500

    Catch exceptions calculating implicit dependencies

    Uncaught exceptions in an overridden add_dependencies() method of a plugin
    can prevent a stack being loaded from the database. To protect against
    programming errors that can result in uncaught exceptions, separate the
    calculation of implicit dependencies out from the calculation of explicit
    dependencies, and ignore exceptions in the latter when dealing with an
    existing stack.

    Change-Id: I939dba57eeba5710bb77a1b30a872fca5d38ad71
    Closes-Bug: #1554625
    (cherry picked from commit 38a46e8d21602e1ebed22c38ba53c0095c6be609)

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/heat 5.0.2 release.