[rdo-list] Adding backwards compatible tripleo-heat-templates packaging

[Alan Pevec]

>> I think something like this (having an openstack-tripleo-heat-templates-compat-mitaka package or similar) would work best.
>>
>> This would also allow us to decide when to drop support for older releases. Newton will have a mitaka-compat package, but we'll sure drop it in a later release, won't we? We could then just control which packages are built for each release using rdoinfo.
>
> If we do this, *every* release will drop a package and add a package.
> The tripleo team won't commit to supporting more than 1 version back
> currently, so -mitaka would only be included with the newton release.

If that's defined in a tripleo spec, please provide a link.

> In Ocata, we'd drop mitaka and add -newton.  This is part of the
> reason that a single tarball made things easier.  Just get the right
> source tarball for old release and build it in a single package.  An
> update per release in a single spec file is generally easier than a
> new package.

How is that done in upstream tripleoci jobs which is testing upgrade?
Is that just checking out stable branch? Link please :)
Problmem with the proposed change is how to supply Source1 to Trunk
builders, currently it handles only single Source0 by replacing it
with the tarball generated from the git checkout. We would have to
keep full Source1 tarball in the distgit and manually keep it in sync
with the stable source branch.
While this might look like a nail-hammer tool deficiency, tracking two
branches in the same package is really adding unnecessary complexity.
What about adding a new package
openstack-tripleo-heat-templates-compat which would be configured in
rdoinfo to take Source0 from the previous stable branch and only that
metadata would get updated for the new release e.g.
- project: tripleo-heat-templates-compat
  tags:
    newton-uc:
      source-branch: stable/mitaka
    newton:
      source-branch: stable/mitaka
   mitaka:
      source-branch: stable/liberty
  conf: rpmfactory-core
  maintainers:
  - mburns at redhat.com

It would install into {_datadir}/%{name}/%{old_name} and
openstack-tripleo-heat-templates could have Requires:
openstack-tripleo-heat-templates-compat so that no changes are
required in the installer.

Cheers,
Alan