Cloned from launchpad blueprint https://blueprints.launchpad.net/heat/+spec/adopt-stack.

Description:

This will allow a stack to be created without creating any resources. Instead the state of some existing resources will be passed in to the adopt action. Partnered with blueprint abandon-stack this will allow stacks to be moved from one heat instance to another.

Possible use cases for abandon/adopt are:
* Moving a stack from a private heat orchestrating on a public cloud to the public heat
* Rebalancing a sharded heat
* Moving stacks off a heat that needs an offline upgrade

It also may be possible to hand-craft the resource state so that an adopt can happen on resources which were not previously created with heat.

A Resource.handle_adopt method will do the following:
* set the supplied resource id
* set the supplied resource data
* set the supplied metadata(?) if different from the template

Some resource subclasses may need to implement their own handle_adopt, but hopefully this will be rare.

Consideration needs to be given to configured endpoints/signal urls on running compute resources, which may stop working when the stack is moved from one heat to another. Ideally existing compute resource will reconfigure themselves for new endpoints.

Specification URL (additional information):

None