[release-4.21] OCPBUGS-71196: Enable existing units without content

[pablintino]

Fixed: OCPBUGS-71196

- What I did

This is a manual cherry-pick of the fixes introduced for OCPBUGS-72396 and OCPBUGS-70259.

Check if a systemd unit exists on the system before attempting to enable or disable it, even when the unit has no content in the MachineConfig. This prevents errors when managing pre-existing system units.

- How to verify it

1. Deploy a 4.21 cluster with this change.
2. Ensure the kdump service is disabled in the worker nodes (it's disabled by default).
3. Apply the following MC:

apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
  labels:
    machineconfiguration.openshift.io/role: worker
  name: 99-worker-custom-enable-kdump
spec:
  config:
    ignition:
      version: 3.1.0
    systemd:
      units:
      - enabled: true
        name: kdump.service  

4. Wait for the worker MCP to finish the update.
5. Check on a worker node that the kdump service is now enabled.

- Description for the changelog

Ensure OS provided units can be enabled with empty Ignition units.

[openshift-ci-robot]

@pablintino: This pull request references Jira Issue OCPBUGS-71196, which is invalid:

• release note text must be set and not match the template OR release note type must be set to "Release Note Not Required". For more information you can reference the OpenShift Bug Process.

Comment /jira refresh to re-evaluate validity if changes to the Jira bug are made, or edit the title of this pull request to link to a different bug.

The bug has been updated to refer to the pull request using the external bug tracker.

Details

In response to this:

Fixed: OCPBUGS-71196

- What I did

This is a manual cherry-pick of the fixes introduced for OCPBUGS-72396 and OCPBUGS-70259.

Check if a systemd unit exists on the system before attempting to enable or disable it, even when the unit has no content in the MachineConfig. This prevents errors when managing pre-existing system units.

- How to verify it

1. Deploy a 4.21 cluster with this change.
2. Ensure the kdump service is disabled in the worker nodes (it's disabled by default).
3. Apply the following MC:

apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
 labels:
   machineconfiguration.openshift.io/role: worker
 name: 99-worker-custom-enable-kdump
spec:
 config:
   ignition:
     version: 3.1.0
   systemd:
     units:
     - enabled: true
       name: kdump.service  

4. Wait for the worker MCP to finish the update.
5. Check on a worker node that the kdump service is now enabled.

- Description for the changelog

Ensure OS provided units can be enabled with empty Ignition units.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the openshift-eng/jira-lifecycle-plugin repository.

[djoshy]

/lgtm

/label backport-risk-assessed

seems sane to me!

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: djoshy, pablintino

The full list of commands accepted by this bot can be found here.

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Details

Needs approval from an approver in each of these files:

• OWNERS [djoshy,pablintino]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[openshift-ci]

@pablintino: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
ci/prow/bootstrap-unit	86f0b36	link	false	/test bootstrap-unit

Full PR test history. Your PR dashboard.

Details

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository. I understand the commands that are listed here.

[pablintino]

/jira refresh

[openshift-ci-robot]

@pablintino: This pull request references Jira Issue OCPBUGS-71196, which is valid. The bug has been moved to the POST state.

7 validation(s) were run on this bug

• bug is open, matching expected state (open)
• bug target version (4.21.0) matches configured target version for branch (4.21.0)
• bug is in the state ASSIGNED, which is one of the valid states (NEW, ASSIGNED, POST)
• release note type set to "Release Note Not Required"
• dependent bug Jira Issue OCPBUGS-70259 is in the state Verified, which is one of the valid states (MODIFIED, ON_QA, VERIFIED)
• dependent Jira Issue OCPBUGS-70259 targets the "4.22.0" version, which is one of the valid target versions: 4.22.0
• bug has dependents

Requesting review from QA contact:
/cc @sergiordlr

The bug has been updated to refer to the pull request using the external bug tracker.

Details

In response to this:

/jira refresh

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the openshift-eng/jira-lifecycle-plugin repository.