cgroup: do not write twice the oom file

[giuseppe]

if a persist_path was provided, then use only that to write the oom file instead of creating it also in the current working directory.

Closes: #504

[Luap99]

Thanks, LGTM

I find it weird that the function is named write and that the error says write too but it really just creates an empty file, but this is pre-existing so I don't mind.

[giuseppe]

I find it weird that the function is named write and that the error says write too but it really just creates an empty file, but this is pre-existing so I don't mind.

good idea, I've renamed it to create_oom_file

[giuseppe]

@haircommander PTAL

[haircommander]

hmm unfortunately cri-o does use the path at the bundle path to find the oom file https://github.com/cri-o/cri-o/blob/04500243ec0cd775e76bcec1c822aaa3faa11177/internal/oci/runtime_oci.go#L1100

conmon ci is broken again but I'm pretty sure this would fail cri-o ci if we merged as-is.

would it be better for you if we explicitly used the value of bundle_path rather than assuming that's cwd. but still write to both?

[giuseppe]

maybe we can fix it in Podman, and run the conmon process from the bundle path itself, or the persistent dir

[giuseppe]

alternative fix for Podman: containers/podman#23243