[openstack-dev] [Nova][Docker] Environment variables

Daniel Kuffner daniel.kuffner at gmail.com
Mon Dec 16 15:18:52 UTC 2013

Hi Russell,

You actually propose to extend the whole nova stack to support
environment variables. Would any other driver benefit from this API

Is that what you imagine?
nova --env SQL_URL=postgres://user:password --image ....

Regarding the discussion you mentioned. Are there any public resources
to read. I kind of missed it. Most likely it was before I was part of
this community :)


On Mon, Dec 16, 2013 at 4:07 PM, 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
> _______________________________________________
> OpenStack-dev mailing list
> OpenStack-dev at lists.openstack.org
> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev

More information about the OpenStack-dev mailing list