MachineConfigs that use 3.4.0 ignition with a kernelArguments are not currently allowed by MCO.

In on-cluster build pools, when we create a 3.4.0 MC with kernelArguments, the pool is not degraded.

No new rendered MC is created either.

 

4.14.0-0.nightly-2023-09-06-065940
 

Always
 

1. Enable on-cluster build in the "worker" pool
2. Create a MC using 3.4.0 ignition version with kernelArguments

apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
  creationTimestamp: "2023-09-07T12:52:11Z"
  generation: 1
  labels:
    machineconfiguration.openshift.io/role: worker
  name: mco-tc-66376-reject-ignition-kernel-arguments-worker
  resourceVersion: "175290"
  uid: 10b81a5f-04ee-4d7b-a995-89f319968110
spec:
  config:
    ignition:
      version: 3.4.0
    kernelArguments:
      shouldExist:
      - enforcing=0

The build process is triggered and new image is built and deployed.

The pool is never degraded.
 

MCs with igition 3.4.0 kernelArguments are not currently allowed. The MCP should be degraded reporting a message similar to this one (this is the error reported if we deploy the MC in the master pool, which is a normal pool):

oc get mcp -o yaml
....
 - lastTransitionTime: "2023-09-07T12:16:55Z"
    message: 'Node sregidor-s10-7pdvl-master-1.c.openshift-qe.internal is reporting:
      "can''t reconcile config rendered-master-57e85ed95604e3de944b0532c58c385e with
      rendered-master-24b982c8b08ab32edc2e84e3148412a3: ignition kargs section contains
      changes"'
    reason: 1 nodes are reporting degraded status on sync
    status: "True"
    type: NodeDegraded

 

When the image is deployed (it shouldn't be deployed) the kernel argument enforcing=0 is not present:
sh-5.1# cat /proc/cmdline 
BOOT_IMAGE=(hd0,gpt3)/ostree/rhcos-05f51fadbc7fe74fa1e2ba3c0dbd0268c6996f0582c05dc064f137e93aa68184/vmlinuz-5.14.0-284.30.1.el9_2.x86_64 ostree=/ostree/boot.0/rhcos/05f51fadbc7fe74fa1e2ba3c0dbd0268c6996f0582c05dc064f137e93aa68184/0 ignition.platform.id=gcp console=tty0 console=ttyS0,115200n8 root=UUID=95083f10-c02f-4d94-a5c9-204481ce3a91 rw rootflags=prjquota boot=UUID=0440a909-3e61-4f7c-9f8e-37fe59150665 systemd.unified_cgroup_hierarchy=1 cgroup_no_v1=all psi=1