Fix on cgroup type determination not in OTP 25

It seems that erts: Allow lack of optional fields when determining cgroup type by jhogberg · Pull Request #7402 · erlang/otp · GitHub is not backported to the latest OTP 25 patch package (25.3.2.7).

Folks tell me that Kubernetes 1.26 enforces cgroupsv2, so Erlang projects on OTP 25 will likely run into issues with CPU quota.

For VerneMQ, as an example, the issue is reported here: [Bug]: Issues with the correct CPU quota detection on k8s v1.26 · Issue #2207 · vernemq/vernemq · GitHub.

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If I understand correctly, below fix is only in OTP 26+.

It seems Erlang projects compiled on OTP < 26 will have trouble on Kubernetes 1.26, due to cgroupsv2.
Has anyone encountered this issue on Kubernetes 1.26 and an idea on how to avoid it?

Apologies for bumping this; it seems like some sort of small thing with the “potential” to getting bitten.
Thanks.

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I can confirm that OTP-25 running on AL2023 sees this issue (gets unknown).

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Hi, sorry for dropping the ball on this. We’re working on fixing another cgroup2 issue on 25/26, and will backport this fix to 25 while we’re at it :slight_smile:

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@jhogberg Thanks for letting us know. I also just realised the fix is deleting a whitespace, would’ve been the shortest patch ever :slight_smile:
Is there public info on the other cgroup2 issue?

Yes, cgroup v2 support is not finding the corrects files · Issue #7928 · erlang/otp · GitHub :slight_smile: