Managing base and other snappy apps

Mark Shuttleworth mark at
Fri Jul 24 06:27:29 UTC 2015

On 24/07/15 03:20, Eystein Måløy Stenberg wrote:
> I am new to Snappy, but have read much of the docs and tried it for a few
> hours.
> No problems and it looks simple so far, but I had a few questions about
> managing snaps.

Welcome aboard and thanks for the questions. I can speak to *intended*
behaviour, others will have a better sense of *current* behaviour and
timing for the convergence of those two :)

> On [1] I get a feeling for how the base system itself is updated. But is
> this entirely managed with the "ubuntu-core" snap? So if I run "snappy
> update ubuntu-core" it will download a new image (if any) to the passive
> partition? Or are there other snaps that should be updated as part of the
> base system as well (I see "generic-amd64" which sounds like a base snap).
> Any other software that comprises a base system update?

The "system" is intended to be defined by three snaps:

 * a platform / kernel snap (ideally shared, like a standard BBB snap)
 * a gadget snap (that describes how the BBB is wedged into this device)
 * the OS snap ("ubuntu-core)

You could update those separately or together, they are all intended to
be transactional with rollback.

generic-amd64 sounds like the kernel snap for a VM or PC device.

> Furthermore, assuming base system update goes well, I should reboot to the
> other partition. Is there a preferred method do this (I see a
> --automatic-reboot option to snappy update) or will the regular "shutdown
> -r now" do the job well enough?

A normal reboot should come up in the correct way.

> Is there a way to see which snaps can be updated? I am looking for
> something similar to "apt-get -s upgrade". Or would this be the difference
> in version between "snappy list -v" and "snappy search"?

Yes, there is a command to see what can be updated, I don't have the
command reference handy on this flight but it's intended for you to be
able to view that and selectively apply the updates you want.

> Finally, is there a way for software to manage snaps, just like you can
> being logged in as superuser with the "snappy" command? I am planning to
> make an application that can update and manage snaps. Supposedly it would
> either need to be part of the base OS (which I guess is unlikely it would
> be allowed to) or it would have to be packaged as a snap with special
> privileges (perhaps as a framework)?

The intent is to expose update management as a service so you can put
your own front end on it for an appliance, say.


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