WIP: MCO NRI plugin experimentation

[ngopalak-redhat]

- What I did

- How to verify it

- Description for the changelog

[openshift-ci]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[openshift-ci]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: ngopalak-redhat
Once this PR has been reviewed and has the lgtm label, please assign yuqi-zhang for approval. For more information see the Code Review Process.

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

Needs approval from an approver in each of these files:

• OWNERS

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

[ngopalak-redhat]

/test unit
/test verify
/test images
/test verify-deps

[openshift-ci]

@ngopalak-redhat: 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/verify	57b5c13	link	true	/test verify

Full PR test history. Your PR dashboard.

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.

[ngopalak-redhat]

@haircommander, I’ve prototyped a POC where the MCO daemon functions as an NRI plugin.
The plugin enforces a strict "deny-by-default" policy for mutations. It only permits mutations in namespaces specified in an allow-list (/etc/crio/nri_plugins/AllowMutations/config.yaml).

• Registers with index 99 to ensure it runs as the final validator.
• Leverages existing MCO configuration capabilities, meaning no additional operators or complex setup are required for the user.
• Basic testing is complete with the changes in the PR and the behavior is stable.

I see two paths for managing the allow-list:

1. API/CRD Approach: MCO parses a specific CRD and applies the config. We can then make sure that users don't play around with system namespaces
2. Direct Override: Users simply override the config file via MCO to specify allowed namespaces.

How do you see proceeding the direction of making Machine Config Daemon (in MCO) a validating NRI plugin for OpenShift?