[release-1.27 | release-1.28] fix: enable the `cloud-node-controller`

[aneesh1]

What type of PR is this?

/kind bug

What this PR does / why we need it:

Overview

In v1.26, the cloud-node-controller was running its reconciliation logic in the cloud-controller-manager, but in v1.27 and v1.28 the it wasn't. When running v1.26 of the cloud-controller-manager in our cluster, we observed that the spec.ProviderID field of nodes was populated, but not when running v1.27 OR v1.28. In addition, we observed NO Update calls by the cloud-controller-manager in v1.27 and v1.28.

We realized that in v1.26, the node-controller was configured to run by default on release-1.26: https://github.com/kubernetes-sigs/cloud-provider-azure/blob/47d04bebceda815d88821badf318ba6bd061e9f5/vendor/k8s.io/cloud-provider/controllers/node/node_controller.go#L181

but in v1.27: https://github.com/kubernetes-sigs/cloud-provider-azure/blob/95a67a1597c85b1565855320c3a8603ece2677ce/vendor/k8s.io/cloud-provider/controllers/node/node_controller.go#L184-L188

and v1.28: https://github.com/kubernetes-sigs/cloud-provider-azure/blob/492d2fb0c241cd0877d9f70c4ef97462f274e252/vendor/k8s.io/cloud-provider/controllers/node/node_controller.go#L188-L192

The node-controller would only run if the workerCount variable was configured.

The workerCount variable gets configured in the NewCloudNodeController function in release-1.27:

https://github.com/kubernetes-sigs/cloud-provider-azure/blob/95a67a1597c85b1565855320c3a8603ece2677ce/vendor/k8s.io/cloud-provider/controllers/node/node_controller.go#L113C6-L118

which is supposed to get configured via the command line argument --concurrent-node-syncs CLI flag: https://github.com/kubernetes-sigs/cloud-provider-azure/blob/be9e1821ee4fec885264eb256192a2bc419efbe4/cmd/cloud-controller-manager/app/core.go#L54

In release-1.27 and release-1.28, this CLI flag is not provided: https://github.com/kubernetes-sigs/cloud-provider-azure/blob/release-1.27/cmd/cloud-controller-manager/app/options/options.go#L134-L155

Justification

The cloud-node-controller configuration was removed from v1.27 and v1.28 of the cloud-controller-manager, thereby preventing the controller from being run. It seems like node-controller should be run as part of the cloud-node-manager instead of cloud-controller-manager. Based on this issue, we understand that the reason behind this change is due to throttling by the cloud-provider, but in v1.26 and prior to the cloud-controller-manager, we did not encounter issues with cloud provider limits on Azure when the node-controller ran in the kube-controller-manager. In addition, if a user does not want to run the node-controller as part of the cloud-controller-manager they can simply exclude it from the list of controllers by doing -cloud-node-controller and can deploy the cloud-node-manager.

Which issue(s) this PR fixes:

Fixes https://github.com/kubernetes-sigs/cloud-provider-azure/issues/1700

Special notes for your reviewer:

Does this PR introduce a user-facing change?

Runs the cloud-node-controller if it is included as part of the list of controllers in the cloud-controller-manager.

[linux-foundation-easycla[bot]]

• :white_check_mark:login: aneesh1 / (d0a7310f288b1ee336ceecfed9ee97823a18226d)

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[aneesh1]

/approve /lgtm

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[nilo19]

This is where the cloud-node-manager starts running, please check. https://github.com/kubernetes-sigs/cloud-provider-azure/blob/master/pkg/nodemanager/nodemanager.go#L190

By the way, the cloud-node-manager runs as a daemonset separated from cloud-controller-manager since very long ago, not from v1.26.