On 18/10/13 03:06, Sam Alba wrote:
Hi all,
I've been recently working on a Docker plugin for Heat that makes it
possible to use Docker containers as resources.
I've just opened the repository:
https://github.com/dotcloud/openstack-heat-docker
Cool, nice work. Thanks for sharing! :)
I agree that we shouldn't see this as a replacement for a Nova driver
(mainly because it doesn't take advantage of Keystone for authenticating
the user, nor abstract the pool of available hosts away from the user),
but it is a really interesting concept to play around with. I too would
definitely welcome it in Heat's /contrib directory where it can be
subject to continuous testing to make sure that any changes in Heat
don't break it.
So, here's a crazy, half-baked idea that I almost posted to the list
last week: we've been discussing adding software configurations to the
HOT format, to allow users (amongst other things) to deploy multiple
independent software configurations to the same Nova VM... when we do so
should we deploy each config in a Linux container?
Discuss.
It's now possible to do that via Nova (since there is now a Docker
driver for it). But the idea here is not to replace the Nova driver
with this Heat plugin, the idea is just to propose a different path.
Basically, Docker itself has a Rest API[1] with all features needed to
deploy and manage containers, the Nova driver uses this API. However
having the Nova API in front of it makes it hard to bring all Docker
features to the user, basically everything has to fit into the Nova
API. For instance, docker commit/push are mapped to nova snapshots,
etc... And a lot of Docker features are not available yet; I admit
that some of them will be hard to support (docker Env variables,
Volumes, etc... how should they fit in Nova?).
The idea of this Docker plugin for Heat is to use the whole Docker API
directly from a template. All possible parameters for creating a
container from the Docker API[2] can be defined from the template.
This allows more flexibility.
Since this approach is a bit different from the normal OpenStack
workflow (for instance, Nova's role is to abstract all computing units
right now), I am interested to get feedback on this.
Obviously, I'll keep maintaining the Docker driver for Nova and I'm
also working on putting together some new features I'll propose for
the next release.
[1] http://docs.docker.io/en/latest/api/docker_remote_api_v1.5/
[2]
http://docs.docker.io/en/latest/api/docker_remote_api_v1.5/#create-a-container
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