_nodes/stats can return host filesystem stats when running in a container

[masseyke]

The _nodes/stats API uses the /proc/diskstats file to get disk usage stats. If elasticsearch is running in a container, and if it is configured so that /proc/diskstats reports stats for the underlying host rather than the container, then the _nodes/stats API will return disk usage stats for the host machine rather than the container.

[elasticsearchmachine]

Pinging @elastic/es-data-management (Team:Data Management)

[lukewhiting]

I have put a call out to the cloud team to get a better understanding of their containers and what the correct method would be to get the required stats. Awaiting a response.

[lukewhiting]

After consulting with cp-stateful, beats team and SRE, we haven't determined a way that it's possible for us, using stock Docker's provided interfaces, to get these statistics in a way that is scoped to the current container.

For that reason, I'm going to close this ticket as a "Won't fix" as we don't believe there's a way to resolve the underlying issue via ES code changes.

[lukewhiting]

Re-opening this issue as, although there's no code fix, It's a good idea to make a note of this scenario in the docs. I'll get a PR for that sorted.

[elasticsearchmachine]

Pinging @elastic/es-docs (Team:Docs)