[openstack-dev] [TripleO] capturing build details in images

James Slagle james.slagle at gmail.com
Thu Dec 5 13:38:32 UTC 2013

On Wed, Dec 4, 2013 at 5:19 PM, Robert Collins
<robertc at robertcollins.net> wrote:
> This is a follow up to https://review.openstack.org/59621 to get
> broader discussion..
> So at the moment we capture a bunch of details in the image - what
> parameters the image was built with and some environment variables.
> Last week we were capturing everything, which there is broad consensus
> was too much, but it seems to me that that is based on two things:
>  - the security ramifications of unanticipated details being baked
> into the image
>  - many variables being irrelevant most of the time
> I think those are both good points. But... the problem with diagnostic
> information is you don't know that you need it until you don't have
> it.
> I'm particularly worried that things like bad http proxies, and third
> party elements that need variables we don't know about will be
> undiagnosable. Forcing everything through a DIB_FOO variable thunk
> seems like just creating work for ourselves - I'd like to avoid that.
> Further, some variables we should capture (like http_proxy) have
> passwords embedded in them, so even whitelisting what variables to
> capture doesn't solve the general problem.
> So - what about us capturing this information outside the image: we
> can create a uuid for the build, and write a file in the image with
> that uuid, and outside the image we can write:
>  - all variables (no security ramifications now as this file can be
> kept by whomever built the image)
>  - command line args
>  - version information for the toolchain etc.

+1.  I like this idea a lot.

What about making the uuid file written outside of the image be in
json format so it's easily machine parseable?

Something like:

dib-<uuid>.json would contain:

  "environment" : {
      "DIB_NO_TMPFS": "1",
  "dib" : {
     "command-line" : ....,
     "version": .....

Could keep adding additional things like list of elements used, build time, etc.

-- James Slagle

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