How to know the version of RHEL CoreOS in OpenShift 4

Environment

• Red Hat OpenShift Container Platform (RHOCP)
  • 4
• Red Hat Enterprise Linux CoreOS (RHCOS)
  • 4

Issue

• How to verify what version of Red Hat CoreOS is running on each node?
• How to verify the Kernel version used by a Red Hat CoreOS node in OpenShift?

Resolution

For checking the RHCOS version and other information from a running OpenShift 4 node:

1. Check the available nodes:

   NAME       STATUS   ROLES                  AGE     VERSION
   master-0   Ready    control-plane,master   4h20m   v1.29.10+67d3387
   master-1   Ready    control-plane,master   4h20m   v1.29.10+67d3387
   master-2   Ready    control-plane,master   4h20m   v1.29.10+67d3387
   worker-0   Ready    worker                 3h57m   v1.29.10+67d3387
   worker-1   Ready    worker                 3h57m   v1.29.10+67d3387
   worker-2   Ready    worker                 3h57m   v1.29.10+67d3387
   

2. Retrieve the desired information from the node (change [node_name] with the desired node name):

       $ oc debug node/[node_name] -- chroot /host bash -c 'cat /etc/redhat-release; grep -E "OPENSHIFT_VERSION=|RHEL_VERSION=|^VERSION=" /etc/os-release; rpm -q kernel' 2>/dev/null
   
       Red Hat Enterprise Linux CoreOS release 4.16
       VERSION="416.94.202411201433-0"
       OPENSHIFT_VERSION="4.16"
       RHEL_VERSION=9.4
       kernel-5.14.0-427.44.1.el9_4.x86_64
   

Refer to RHEL CoreOS Kernel versions in OpenShift 4 for a list of Kernel versions in different OpenShift 4 releases.

Root Cause

Is it possible to check the RHCOS version and other data by accessing the nodes.

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