extra-files: add udev rule for snap auto-import

[mardy]

This file has always been shipped by snapd, but we are about to remove
it from there because it causes issues on recent classic systems.

See also: https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1966203

[alfonsosanchezbeato]

LGTM, thanks! Which is the PR removing from snapd?

[bboozzoo]

Core22 has this: canonical/core-base#35 should we add something similar here too? Does udev/systemd from 16.04 even has the necessary support?

[mardy]

LGTM, thanks! Which is the PR removing from snapd?

It will come later, after the core snap has been released. By the way, how often does that happen?

[mardy]

Core22 has this: snapcore/core-base#35 should we add something similar here too? Does udev/systemd from 16.04 even has the necessary support?

No, it doesn't. In core22 that change was needed to workaround the security restrictions recently added to the udev unit file; but in previous Ubuntu distributions these restrictions are not there, so we can safely use unshare and call mount(). :-)

[valentindavid]

Has this been opened also in snapcore/core20 and snapcore/core18? I think those will need the fix too.

[mardy]

Has this been opened also in snapcore/core20 and snapcore/core18? I think those will need the fix too.

No, they already have their udev rules. Links in https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1966203/comments/13