Add (linux).process.cgroup attribute

[rogercoll]

Area(s)

area:system

Is your change request related to a problem? Please describe.

The hostmetrics receiver is currently reporting the process.cgroup attribute: https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/main/receiver/hostmetricsreceiver/internal/scraper/processscraper/metadata.yaml#L49

This attribute is really helpful as it can be used to extract containerization information like the K8s pod UID and/or the container ID which the process is running on.

Describe the solution you'd like

Standardize the process.cgroup attribute.

Describe alternatives you've considered

As cgroups being a Linux only technology, would it make sense to add the attribute under the linux namespace (e.g linux.process.cgroup)?

Additional context

No response

[braydonk]

I'm in favour of this attribute being under the linux namespace.

[trisch-me]

Hey @rogercoll, don't you think process will be better option for it? I know it's specific to linux, but process is common for all OS. I think the important namespace here is process and not the linux

@mjwolf what do you think?

[mjwolf]

I think this would be better under process as well. There are already OS specific attributes in process; process.owner is Windows specific while process.user.id and process.group.id. #1329 will also add another one with gnu.build_id. So I don't see a problem with adding process.cgroup, and it seems like a more natural location to me.

[rogercoll]

don't you think process will be better option for it?

I don't have a strong opinion about it, given that we already have OS specific attributes without the OS namespace it might make sense to have a unified approach (without OS).

We discussed this naming issue during today's system SIG and we notice that some attributes contain the OS while others don't, I think we should agree on the structure and fix these nuances. #1403