Add checks for atomic update compatibility

[mtravitzky]

This checks for packages installing into locations which are illegal for compatibility with atomic updates. E.g. a package which installs into /var/ would get corrupted after a rollback from a newer snapshot.

[danigm]

This looks good, can you review the flake8 formatting errors?

It could be also nice to have some specific tests for this, but I can add that in later PR.

[mtravitzky]

Re-ran flake8 locally, should be fine now

[danigm]

@mtravitzky the check looks good, but maybe we should tweak the default configuration, at least for now. It's probably not wise to set the badness to 10000 immediately, it could produce a lot of broken packages in Factory once this change lands on the rpm package.

[Conan-Kudo]

I'm not sure this check is valid, since it's completely valid to install things into /var, even in transactional update mode. Otherwise it's probably impossible to set up directory hierarchies and initialize data trees for persistent data required for applications and services.

[Vogtinator]

I'm not sure this check is valid, since it's completely valid to install things into /var, even in transactional update mode.

No, /var is not available inside the transactional environment. It's not part of the snapshotted part of the system.

Otherwise it's probably impossible to set up directory hierarchies and initialize data trees for persistent data required for applications and services.

Programs which need a specific hierarchy in /var can request creation through tmpfiles.d or create it on first start.

(For now there's still the "create-dirs-from-rpmdb" service which looks at the RPM database for directory creation, but it'll be removed in the future)

[mtravitzky]

@mtravitzky the check looks good, but maybe we should tweak the default configuration, at least for now. It's probably not wise to set the badness to 10000 immediately, it could produce a lot of broken packages in Factory once this change lands on the rpm package.

What badness would you suggest? Something like 900?

[FilippoBonazziSUSE]

In the logrotate check we first set it to 100 and then recently raised it to 10000 once we were sure that Factory was clean. It's an arbitrary value but I think it works fine as a reference.

[mtravitzky]

In the logrotate check we first set it to 100 and then recently raised it to 10000 once we were sure that Factory was clean. It's an arbitrary value but I think it works fine as a reference.

Sounds good, so that's what I just did 🙂

[danigm]

Looks good, just fix the comment to match the config new value