"Items to join must be strings" - Intrinsic functions resolve before get_input in StructuredConfig resource

[Robert Collins]

Trying to use Fn::Join with a software deployment using get_input -

Fn::Join:
 - ':'
 - - get_input: foo
   - "bar"

errors on stack-update, showing "Items to join must be strings"

https://review.openstack.org/108135 let me see what errors which is this:

 Items to join must be strings {u'get_input': u'controller_host'}

which can't be resolved by function.resolve as its not a function :).

Raising the log level on the server let me see this: (btw - shouldn't need to do that :/)

2014-07-18 10:40:52.282 20240 ERROR heat.engine.parser [req-8a28db27-f5ef-4df0-960a-36d562977414 None] Property error : SSLConfig: config Items to join must be strings
2014-07-18 10:40:52.282 20240 TRACE heat.engine.parser Traceback (most recent call last):
2014-07-18 10:40:52.282 20240 TRACE heat.engine.parser File "/opt/stack/venvs/heat/local/lib/python2.7/site-packages/heat/engine/parser.py", line 418, in validate
2014-07-18 10:40:52.282 20240 TRACE heat.engine.parser result = res.validate()
2014-07-18 10:40:52.282 20240 TRACE heat.engine.parser File "/opt/stack/venvs/heat/local/lib/python2.7/site-packages/heat/engine/resource.py", line 640, in validate
2014-07-18 10:40:52.282 20240 TRACE heat.engine.parser return self.properties.validate()
2014-07-18 10:40:52.282 20240 TRACE heat.engine.parser File "/opt/stack/venvs/heat/local/lib/python2.7/site-packages/heat/engine/properties.py", line 322, in validate
2014-07-18 10:40:52.282 20240 TRACE heat.engine.parser raise exception.StackValidationFailed(message=msg)
2014-07-18 10:40:52.282 20240 TRACE heat.engine.parser StackValidationFailed: Property error : SSLConfig: config Items to join must be strings
2014-07-18 10:40:52.282 20240 TRACE heat.engine.parser

[Robert Collins (lifeless)]

So it looks to me like its trying to get the property value, but you can't do that in a late bound config, you can only check that the structure is right, no ?

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.openstack.org/108157

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/108158

[OpenStack Infra (hudson-openstack)]

Change abandoned by Clint 'SpamapS' Byrum (<email address hidden>) on branch: master
Review: https://review.openstack.org/108158
Reason: This is not going to be possible.

[Clint Byrum (clint-fewbar)]

This is not even close to a simple problem to solve.

The software config object is managed outside of the stack. So any intrinsic functions will not have any access to the stack itself. This is by design to support encapsulation. However, we do need these intrinsic functions to be passed in so they can be used from within the config:.

I feel that this is not going to be possible without some deep thought.

So, the work around for TripleO will need to be to do concatenation of inputs in the o-a-c template, rather than in the Heat templates.

[Tomas Sedovic (tsedovic)]

I'm having a similar issue with joining attributes of ResourceGroup's inner resources:

  servers:
    type: OS::Heat::ResourceGroup
    properties:
      count: 3
      resource_def:
        type: OS::Nova::Server
        properties:
          image: overcloud-compute
          flavor: baremetal

  allNodesConfig:
    type: OS::Heat::StructuredConfig
    properties:
      config:
        completion-signal:
          get_input: deploy_signal_id
        names:
          list_join:
          - ','
          - {get_attr: [servers, name]}

heat stack-create reports: ERROR: Property error : allNodesConfig: config "list_join" must operate on a list.

[Zane Bitter (zaneb)]

What Tomas is seeing looks like an unrelated error - presumably due to get_attr returning None.

[Tomas Sedovic (tsedovic)]

Looks like you're right, Zane. Filed a separate bug here: https://bugs.launchpad.net/heat/+bug/1358831

[OpenStack Infra (hudson-openstack)]

Change abandoned by Clint 'SpamapS' Byrum (<email address hidden>) on branch: master
Review: https://review.openstack.org/108157
Reason: ENOTIME

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/314986

[OpenStack Infra (hudson-openstack)]

Change abandoned by Sharat Sharma (<email address hidden>) on branch: master
Review: https://review.openstack.org/314986

[Zane Bitter (zaneb)]

Realistically, this is never going to get fixed. Intrinsic functions can only be evaluated in the context of the template (since they may mean different things in different template versions), but software configs are created by a separate API that is not associated with a template. As long as get_input looks like an intrinsic function, this is not fixable.

The only alternative would be some sort of string-based substitution format, carefully chosen not to conflict with any likely to appear in the config payload.