[ArangoDB] Add section about Limiting resource utilization

[Simran-B]

https://www.arangodb.com/docs/devel/programs-arangod-env-vars.html

[tianon]

I've left a few suggestions based on our fork of markdownfmt (which is what the CI failure is).

I'm also going to cc the arangodb image maintainers for confirmation/review: @fceller @dothebart @KVS85

[dothebart]

@tianon thanks, I've discussed with my collegue @Simran-B (who is mainly responsible for the arangodb documentation) to create this PR beforehand.

Hope you like it, as we seem to have users having problems about arangodb not adjusting memory usage.
We found it a bit of a pity to add this workaround, as without docker ArangoDB would use the proc filesystem to retrieve this information. Is there any easy (or default by convention) way for a programm to determine its memory resources in a docker container to have a more common sense or at best automatic solution for this?

Cheers from Cologne,
Willi

[yosifkit]

Is there any easy (or default by convention) way for a programm to determine its memory resources in a docker container to have a more common sense or at best automatic solution for this?

I think the canonical place is /sys/fs/cgroup/memory/memory.limit_in_bytes (https://www.kernel.org/doc/Documentation/cgroup-v1/memory.txt), but that may be different in future systems using cgroup-v2 (https://www.kernel.org/doc/Documentation/cgroup-v2.txt).

[tianon]

arangodb/arangodb#11682 looks nice! 👍

Do you still want to merge this PR in the interim? (just double checking before I hit merge 😄)

[Simran-B]

Yes, please! It will remain relevant for at least 3.6, which may not receive a backport, and for the 3.7 alpha versions which are already out there.

We will open another PR once the new implementation landed.