🌱 Allows to redefine ETCD client logger

[dmvolod]

What this PR does / why we need it:
For some reasons, we need to adjust ECTD client logger level to avoid have an unpredictable number of warnings in the log, like

{"level":"warn","ts":"2025-05-22T16:36:08.530926Z","caller":"[email protected]/retry_interceptor.go:63","msg":"retrying of unary invoker failed","target":"etcd-endpoints://0xc016cf01e0/etcd-test-control-plane-dx4r5","attempt":0,"error":"rpc error: code = DeadlineExceeded desc = latest balancer error: last connection error: connection error: desc = \"transport: Error while dialing: error upgrading connection: error sending request: Post \\\"https://XXX.XX.XX.XX:6443/api/v1/namespaces/kube-system/pods/etcd-test-control-plane-dx4r5/portforward?timeout=10s\\\": EOF\""}
{"level":"warn","ts":"2025-05-22T16:36:23.642869Z","caller":"[email protected]/retry_interceptor.go:63","msg":"retrying of unary invoker failed","target":"etcd-endpoints://0xc0041314a0/etcd-test-control-plane-dx4r5","attempt":0,"error":"rpc error: code = DeadlineExceeded desc = received context error while waiting for new LB policy update: context deadline exceeded"}
{"level":"warn","ts":"2025-05-22T16:37:11.809235Z","caller":"[email protected]/retry_interceptor.go:63","msg":"retrying of unary invoker failed","target":"etcd-endpoints://0xc01595fa40/etcd-test-control-plane-dx4r5","attempt":0,"error":"rpc error: code = DeadlineExceeded desc = latest balancer error: last connection error: connection error: desc = \"transport: Error while dialing: error upgrading connection: error sending request: Post \\\"https://XXX.XX.XX.XX:6443/api/v1/namespaces/kube-system/pods/etcd-test-control-plane-dx4r5/portforward?timeout=10s\\\": EOF\""}
{"level":"warn","ts":"2025-05-22T16:37:30.158754Z","caller":"[email protected]/retry_interceptor.go:63","msg":"retrying of unary invoker failed","target":"etcd-endpoints://0xc009898f00/etcd-test-control-plane-dx4r5","attempt":0,"error":"rpc error: code = DeadlineExceeded desc = received context error while waiting for new LB policy update: context deadline exceeded"}

But now, ETCD log level is hardcoded to the zapcore.InfoLevel. This PR allows to redefine it on init in the embedded controllers. If we need to redefine it globally with env variable or run option for any deployment, please let me know.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

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[dmvolod]

/area provider/control-plane-kubeadm

[sbueringer]

Wondering if kubernetes has a similar use case and how are they handling it (e.g. in the kube-apiserver)

[dmvolod]

Wondering if kubernetes has a similar use case and how are they handling it (e.g. in the kube-apiserver)

This is a very good point. It doesn't work in kube-apiserver at the moment, because community copied/pasted (https://github.com/kubernetes/kubernetes/blob/b35c5c0a301d326fdfa353943fca077778544ac6/staging/src/k8s.io/apiserver/pkg/storage/storagebackend/factory/etcd3.go#L97-L111) the etcdClientDebugLevel function from etcd, which is no longer actual for now. I will plan to create a similar PR for Kubernetes also.

I requested an export of this function in the PR etcd-io/etcd#20006. But as far as I understand, there are no plans to backport it to etcd 3.5.

The only downside to this approach is that it won't work natively. We can have both approaches at the same time to get a universal solution. That is, set the logger via a function and change the logging level via ETCD_CLIENT_DEBUG variable. The only thing is that at the moment we will also have to copy/paste the function until the release of etcd 3.6 with this fix is ​​released and we will not switch to it. I could create and track this issue.

[sbueringer]

I was wondering if there is a way to "reuse" our regular log level for the etcd logger

[dmvolod]

I was wondering if there is a way to "reuse" our regular log level for the etcd logger

Seems to with some trick like that, it could be possible, but should be validated

func (r *KubeadmControlPlaneReconciler) SetupWithManager(ctx context.Context, mgr ctrl.Manager, options controller.Options) error {
	logger, _ := logutil.CreateDefaultZapLogger(zapcore.Level(ctrl.LoggerFrom(ctx).GetV()))
	etcd.SetLogger(logger)