Currently signalling via 99-refresh-completed only uses the legacy
curl data payload (e.g that for CFN compatible WaitConditions),
but now we're using it exclusively for signalling SoftwareDeployment
resources, which support a different payload, including deploy_stdout
which is accessible via a resource attribute.
Returning a payload for deploy_stdout containing the derived config ID
is potentially useful as it changes whenever the SoftwareConfig or any
inputs change, thus can be used as a unique identifier for dependent
resources which need to be re-triggered when some config is reapplied,
for example puppet manifests with a dependency on hieradata applied
via a SoftwareDeployment.
get_attr: [ControllerDeployment, deploy_stdout]
Partial-Bug: #1463092
Change-Id: Ic62b6303795f70f3b9ace46731a21d1c0e7fe6c7
e6b9609473