Ensure platform-specific code is correctly namespaced

[smortex]

Facter facts and providers are sometimes tied to a specific platform (e.g. Linux, FreeBSD, etc). When it is the case, they are placed in a directory named after this platform.

Some files are incorrectly stored in the base directory making it less obvious that they are platform-specific.

This PR fix this issue and is part 1/2 of a fix for #2742

[puppetlabs-jenkins]

Can one of the admins verify this patch?

[joshcooper]

Thanks @smortex! Moving the containers resolver makes sense based on my reading of https://wiki.freebsd.org/Containers, but what about the others like dmi? What about them makes them linux specific? Is it the /sys/class filesystem?

When adding resolvers in the future, what's the best way to determine if something is linux-specific or not? Wondering if maybe there's a good reference/porting guide we could refer to?

Also could you resolve conflicts?

[smortex]

Hey @joshcooper, I am catching up after long holiday away from home

Thanks @smortex! Moving the containers resolver makes sense based on my reading of wiki.freebsd.org/Containers, but what about the others like dmi? What about them makes them linux specific? Is it the /sys/class filesystem?

Indeed, /sys is something that is not available on FreeBSD and probably some other namespacing could be done if dmi facts are collected there. My goal in this PR is to eventually fix a warning that is produced with the latest code. As far as I can see, the dmi facts do not produce warnings when attempting to access /sys/....

When adding resolvers in the future, what's the best way to determine if something is linux-specific or not? Wondering if maybe there's a good reference/porting guide we could refer to?

Ughhhhh 😦 No real idea. Some acceptance tests that would run on various operating systems and ensure that no warning / error is produced may help… but that's non-trivial. Maybe creating a team with people interested in "exotic" operating systems and pinging that team when new provider are added may be simpler 🤷 ?

Also could you resolve conflicts?

Done!