Docker memory metrics don't consider cgroups version of running container

[fearful-symmetry]

Right now, the docker/memory metrics just do this to fetch RSS memory:

totalRSS := myRawStat.Stats.MemoryStats.Stats["total_rss"]

The problem is, the Stats object reports different metrics depending on the cgroups version: https://github.com/moby/moby/blob/master/daemon/stats_unix.go. That total_rss field isn't on V2.

The code doesn't consider this, and the docs only mention it briefly: https://docs.docker.com/engine/api/v1.45/#tag/Container/operation/ContainerStats

[elasticmachine]

Pinging @elastic/elastic-agent-data-plane (Team:Elastic-Agent-Data-Plane)

[andrew-moldovan]

@fearful-symmetry @pierrehilbert any updates on this one? It would really help us out with https://elasticco.atlassian.net/browse/CP-2371

[fearful-symmetry]

huh, I thought this was fixed months ago, I can take a look.