About changing the pids_limit in OSD or ROSA

Solution Verified - Updated -

Environment

  • Red Hat OpenShift Service on AWS (ROSA)
    • 4.8
    • 4.9
    • 4.10
  • Red Hat OpenShift Dedicated (OSD)
    • 4.8
    • 4.9
    • 4.10

Issue

  • How to change the value of pids_limit/pidsLimit in OSD or ROSA.
  • Is it possible to customize crio.conf in OSD or ROSA?

Resolution

The specific pidsLimit is not user configurable on any OSD or ROSA cluster before 4.11.

Note: For OSD/ROSA 4.11 or newer, please refer to Change pids_limit in OSD/ROSA 4.11 and newer.

As of the following versions, the default per-pod pidsLimit is 4096:

  • 4.8.35
  • 4.9.26
  • 4.10.6

To enable this new default value, please upgrade the OSD/ROSA cluster to any of these or newer versions.

Note: In previous OSD/ROSA versions, the default per-pod pidsLimit was the OpenShift default of 1024.

Root Cause

It's not possible to customize CRI-O configurations in OSD or ROSA before 4.11. While it's not possible to configure the pidsLimit or other CRI-O configurations in OSD or ROSA, the fleet wide default pidsLimit was changed per the above resolution.
Refer to the documentation for additional information: Compute nodes in OSD, Compute nodes in ROSA.

Diagnostic Steps

Check the CRI-O pids_limit in the nodes (if there is no pids_limit in the output, the value is the old default 1024):

$ oc get nodes
[...]
$ oc debug node/[node_name] -- chroot /host bash -c 'crio config | grep pid'
time="2022-01-01 00:00:01.117272995Z" level=info msg="Starting CRI-O, version: 1.22.1-21.rhaos4.9.git74a7981.2.el8, git: ()"
level=info msg="Using default capabilities: CAP_CHOWN, CAP_DAC_OVERRIDE, CAP_FSETID, CAP_FOWNER, CAP_SETGID, CAP_SETUID, CAP_SETPCAP, CAP_NET_BIND_SERVICE, CAP_KILL"
pids_limit = 4096

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