Warnings about NUMA while starting up the container

[w1ndy]

Hi,

I'm running the mongo image on a NUMA-enabled machine, and I get following warning from logs when MongoDB is starting:

WARNING: You are running on a NUMA machine.
We suggest launching mongod like this to avoid performance problems:
numactl --interleave=all mongod [other options]

How can I resolve this? Any help is appreciated, thanks.

[w1ndy]

Seccomp is preventing numactl from working correctly, because get_mempolicy and set_mempolicy syscall is restricted in docker containers. Possible workarounds include:

1. Run without seccomp: docker run --security-opt seccomp=unconfined mongo
2. Run with a custom seccomp profile: docker run --security-opt seccomp=./seccomp.json mongo

Hope it helps other people who ran into the same problem. Maybe we can add it into docs? For reference: https://docs.docker.com/engine/security/seccomp/

[tianon]

Indeed, adding this to the documentation (https://github.com/docker-library/docs/tree/master/mongo) would be extremely appreciated.

Our current test already includes something like this (creating a custom seccomp profile on the fly): https://github.com/docker-library/official-images/blob/98d3a4d3cecc8b53e0ea547337eeff53ff58710e/test/tests/mongo-basics/run.sh#L6-L53

[tianon]

To improve on this, adding --cap-add SYS_NICE to your container arguments is sufficient to allow NUMA to do the right thing.