Installing core snap in container often fails

[Michał Sawicz]

Very often, when trying to build a snap with SNAPCRAFT_CONTAINER_BUILDS=1, the build fails to install the core snap:

Looking up assertion ['account-key', 'public-key-sha3-384=BWDEoaqyr25nF5SNCvEv2v7QnM9QsfCc0PBMYD_i2NGSQ32EF2d4D0hqUel3m8ul']
Looking up assertion ['snap-declaration', 'snap-name=core']
Looking up assertion ['snap-revision', 'snap-revision=2844', 'snap-id=99T7MUlRhtI3U0QFgl5mXXESAiSwt776']
Adding assertion core_2844.assert
Installing /run/core_2844.snap
error: cannot perform the following tasks:
- Copy snap "core" data (cannot copy "/var/snap/core/2844" to "/var/snap/core/2844": failed to copy all: "cp: cannot stat '/var/snap/core/2844': No such file or directory" (1))

It seems to be trying to refresh to the same core revision that already exists?

[John Lenton (chipaca)]

there was a bug in snapd,
https://forum.snapcraft.io/t/cant-re-install-existing-snap/1824/9
which has been fixed but not yet released to stable; it should be in 2.28.
There's also a minor bug in snapcraft that triggers it, see
https://forum.snapcraft.io/t/snapcraft-container-builds-triggering-a-bug-in-snapd/1990

[Sergio Schvezov (sergiusens)]

I will mark this as invalid given that this is a snapd bug. That said, we are moving to only installing the core snap if the version has changed so will set it to triaged instead and repurpose the bug for that task.

[Cris Dywan (kalikiana)]

https://github.com/snapcore/snapcraft/pull/1568