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Hi Russel,

I have something that is pushing it for to stay in nova (at least the
compute drivers). I should have a gerrit branch for people to review soon.

Regards
chuck


On Mon, Dec 16, 2013 at 10:07 AM, Russell Bryant <rbryant at redhat.com> wrote:

> On 12/16/2013 09:27 AM, Daniel Kuffner wrote:
> > Hi All,
> >
> > I have submitted a new blueprint which addresses the a common pattern
> > in the docker world. A usual pattern in the docker world is to use
> > environment variables to configure a container.
> >
> > docker run -e "SQL_URL=postgres://user:password@/db" my-app
> >
> > The nova docker driver doesn't support to set any environment
> > variables. To work around this issue I used cloud-init which works
> > fine. But this approach has of course the drawback that a) I have to
> > install the cloud init service. and b) my docker container doesn't
> > work outside of openstack.
> >
> > I propose to allow a user to set docker environment variables via nova
> > instance metadata. The metadata key should have a prefix like ENV_
> > which can be used to determine all environment variables. The prefix
> > should be removed and the remainder key and vaule will be injected.
> >
> > The metadata can unfortunately not be set in horizon but can be used
> > from the nova command line tool and from heat. Example heat:
> >
> > myapp:
> >     Type: OS::Nova::Server
> >     Properties:
> >       flavor: m1.small
> >       image: my-app:latest
> >       meta-data:
> >         - ENV_SQL_URL: postgres://user:password@/db
> >         - ENV_SOMETHING_ELSE: Value
> >
> >
> > Let me know what you think about that.
> >
> > Blueprint:
> https://blueprints.launchpad.net/nova/+spec/docker-env-via-meta-data
>
> Thanks for starting the discussion.  More people should do this for
> their blueprints.  :-)
>
> One of the things we should be striving for is to provide as consistent
> of an experience as we can across drivers.  Right now, we have the
> metadata service and config drive, and neither of those are driver
> specific.  In the case of config drive, whether it's used or not is
> exposed through the API.  As you point out, the meta-data service does
> technically work with the docker driver.
>
> I don't think we should support environment variables like this
> automatically.  Instead, I think it would be more appropriate to add an
> API extension for specifying env vars.  That way the behavior is more
> explicit and communicated through the API.  The env vars would be passed
> through all of the appropriate plumbing and down to drivers that are
> able to support it.
>
> This is all also assuming that containers support is staying in Nova and
> not a new service.  That discussion seems to have stalled.  Is anyone
> still pushing on that?  Any updates?
>
> --
> Russell Bryant
>
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