Support for core24 base

[Callahan Kovacs]

Hello,

We've been adding support for snapcraft to bootstrap the core24 snap and allowing developers early access to build on a core24 base.

The snapd team is getting close to releasing an edge version of the core24 snap. They'll need support from Launchpad to build the core24 snap on different architectures.

Thanks!

[Valentin David (valentin.david)]

Now snapcraft 7.4 has been released with all we need, we are now blocked by launchpad missing "devel" as build base. I have tried to run a build, but got the error:

(No such base: 'devel'.)

Could you add that base?

[Colin Watson (cjwatson)]

I created these new snap bases in Launchpad:

In [1]: lp.snap_bases.new(name='devel', display_name='devel', distro_series='/ubuntu/mantic', build_channels={'snapcraft': 'stable/launchpad-buildd'}, features={'allow_duplicate_build_on': True})
Out[1]: <snap_base at https://api.launchpad.net/devel/+snap-bases/devel>

In [2]: lp.snap_bases.new(name='core24', display_name='core24', distro_series='/ubuntu/mantic', build_channels={'snapcraft': 'stable/launchpad-buildd'}, features={'allow_duplicate_build_on': True})
Out[2]: <snap_base at https://api.launchpad.net/devel/+snap-bases/core24>

These will need to be updated when new Ubuntu series are opened; the linked ubuntu-release-tools MP documents the procedure there.

With the preparatory work we've done here, the Launchpad side of setting up core26 (etc.) should be much simpler. As it stands now, the procedure should be:

 * Ubuntu Core: get an initial version of coreXX (e.g. core26) into the store
 * Launchpad: run `lp.snap_bases.new(name='coreXX', display_name='coreXX', distro_series='/ubuntu/whatever-is-current-at-that-time', build_channels={'snapcraft': 'stable/launchpad-buildd'}, features={'allow_duplicate_build_on': True})` (copy `build_channels` and `features` from the previous core version)
 * Launchpad: add whichever coreXX it is to `lp.services.fields.SnapBuildChannelsField._core_snap_names`, to allow snap recipes that use coreXX to control which channel is used for it