Release arg in ubuntu-device-flash

Martin Pitt martin.pitt at
Mon Jun 8 16:16:39 UTC 2015

Sergio Schvezov [2015-06-08 12:54 -0300]:
> >  * Why is this necessary at all?
> Because we are moving to the new concept for channels, per snappy
> package and driven by the store. The system image channels which were
> both a channel and a release are going away.

Ah, so this:

          [core command options]
          --channel=        Specify the channel to use (stable)

does not need to be specified any more, and will go away? I. e. the
release argument replaces the --channel option eventually?

> >  * How can a program find out the correct release for a given channel?
> I don't understand this question, but snappy cares for the release, not
> the channel for finding packages on the store. Packaging has no encoding
> for the release.

OK, if the release is the new "primary" selector, asked the other way
around: How can a program find out an appropriate channel for a given

$ sudo ubuntu-device-flash core -o /tmp/snappy.img rolling
Channel ubuntu-core/rolling/stable not found on server

Can this get some sensible default?

I suppose "--channel edge" would be an okay default for testing until

> >  * What's the recommended way to find out whether or not u-d-f needs
> >    this argument? Is there anything easier than parsing --help output?
> This is a required argument and I regret ever adding a manpage.

I meant, if we want to write something (like the autopkgtest setup
script) that constructs a snappy image and which should work on all
Ubuntu (host) releases, I need to determine whether u-d-f wants
channels like "ubuntu-core/devel-proposed" or a channel like "edge"
plus a release. My first approximation would be

  ubuntu-device-flash core --help | grep -q Release

but I was wondering if there's something less brittle?



Martin Pitt                        |
Ubuntu Developer (  | Debian Developer  (

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