Open Stack

All,

We've got some requirements around adding some interfaces to the heat
environment file format, for example:

1. Now that we support passing un-merged environment files to heat, it'd be
good to support an optional description key for environments, such that we
could add an API (in addition to the one added by jdob to retrieve the
merged environment for a running stack) that can retrieve
all-the-environments and we can easily tell which one does what (e.g to
display in a UI perhaps)

2. We've got requirements around merge strategies for multiple environments
with potentially colliding keys.  Similar to the cloud-init merge
strategy[1] works.  Basically it should be possible to include multiple
environments then have heat e.g append to a list parameter_default instead
of just last-one-wins.

Both of these will likely require some optional additions to the
environment file format - can we handle them just like e.g event_sinks and
just add them?

Clearly since the environment format isn't versioned this poses a
compatibility problem if "new" environments are used on an old heat, but to
be fair we have done this before (with both parameter_defaults and
event_sinks)

What do folks think, can we add at least the description, and what
interface makes sense for the merge strategy (annotation in the environment
vs data passed to the API along with the environment files list?)

Any thoughts on the above would be great :)

Thanks,

Steve

[1] http://cloudinit.readthedocs.io/en/latest/topics/merging.html
[2] https://github.com/openstack/python-heatclient/blob/master/heatclient/common/environment_format.py#L22