✨ Allow to disable KubeProxy and CoreDNS #12359

sathieu · 2025-06-13T21:11:18Z

What this PR does / why we need it:

Disabling kube-proxy using controlplane.cluster.x-k8s.io/skip-kube-proxy annotation is not enough because kubeadm will try to pull the kube-proxy image on preflight.

The proper way to disable kube-proxy is to use Proxy.Disable=true, as in this PR.

Which issue(s) this PR fixes:
Related to #12288

/area provider/bootstrap-kubeadm

k8s-ci-robot · 2025-06-13T21:11:26Z

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k8s-ci-robot · 2025-06-13T21:11:28Z

Hi @sathieu. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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fabriziopandini · 2025-06-21T09:53:54Z

I would like to better understand the transition from where we are today to the target state.

As of today, the API only allows users to delegate to kubeadm installation of core DNS and kube-proxy, and the annotation allows users to take ownership of the management of the upgrades of those addons.

With this PR, I assume we are adding a third use case, which is take ownership of both installation and management of CoreDNS and kube-proxy, but it is not clear if both the existing use cases are going to be still supported.

(BTW, in my opinion we have to support all of them, and possibly more to a more consistent API).

sivchari

Thank you for working on this! I left some comments.

sivchari · 2025-06-22T07:32:27Z

api/bootstrap/kubeadm/v1beta1/kubeadm_types.go

+	// Proxy defines the options for the proxy add-on installed in the cluster.
+	Proxy Proxy `json:"proxy,omitempty"`
 }


Suggested change

// Proxy defines the options for the proxy add-on installed in the cluster.

Proxy Proxy `json:"proxy,omitempty"`

}

// Proxy defines the options for the proxy add-on installed in the cluster.

// +optional

Proxy *Proxy `json:"proxy,omitempty"`

This field is optional, so it would be good to add the optional marker and make it be pointer.

sivchari · 2025-06-22T07:34:00Z

api/bootstrap/kubeadm/v1beta1/kubeadm_types.go

+	// Disabled specifies whether to disable this addon in the cluster
+	Disabled bool `json:"disabled,omitempty"`


Suggested change

// Disabled specifies whether to disable this addon in the cluster

Disabled bool `json:"disabled,omitempty"`

// Disabled specifies whether to disable this addon in the cluster

// +optional

Disabled *bool `json:"disabled,omitempty"`

sivchari · 2025-06-22T07:34:14Z

api/bootstrap/kubeadm/v1beta1/kubeadm_types.go

+	// Disabled specifies whether to disable this addon in the cluster
+	Disabled bool `json:"disabled,omitempty"`


Suggested change

// Disabled specifies whether to disable this addon in the cluster

Disabled bool `json:"disabled,omitempty"`

// Disabled specifies whether to disable this addon in the cluster

// +optional

Disabled *bool `json:"disabled,omitempty"`

sivchari · 2025-06-22T07:34:27Z

api/bootstrap/kubeadm/v1beta2/kubeadm_types.go

+// Proxy defines the proxy addon that should be used in the cluster
+type Proxy struct {
+	// Disabled specifies whether to disable this addon in the cluster
+	Disabled bool `json:"disabled,omitempty"`


sivchari · 2025-06-22T07:35:40Z

api/bootstrap/kubeadm/v1beta1/kubeadm_types.go

Do we need to add these changes to v1beta1 ? I think it's good way to only add these to v1beta2.

sivchari · 2025-06-22T07:38:01Z

controlplane/kubeadm/internal/controllers/controller_test.go

+		objs := []client.Object{
+			cluster.DeepCopy(),
+			corednsCM.DeepCopy(),
+			kubeadmCM.DeepCopy(),
+		}
+		kcp := kcp.DeepCopy()
+		kcp.Spec.KubeadmConfigSpec.ClusterConfiguration.DNS.Disabled = true
+
+		depl := depl.DeepCopy()
+
+		depl.Spec.Template.Spec.Containers[0].Image = "my-cool-image!!!!" // something very unlikely for getCoreDNSInfo to parse
+		objs = append(objs, depl)


Suggested change

objs := []client.Object{

cluster.DeepCopy(),

corednsCM.DeepCopy(),

kubeadmCM.DeepCopy(),

}

kcp := kcp.DeepCopy()

kcp.Spec.KubeadmConfigSpec.ClusterConfiguration.DNS.Disabled = true

depl := depl.DeepCopy()

depl.Spec.Template.Spec.Containers[0].Image = "my-cool-image!!!!" // something very unlikely for getCoreDNSInfo to parse

objs = append(objs, depl)

depl := depl.DeepCopy()

depl.Spec.Template.Spec.Containers[0].Image = "my-cool-image!!!!" // something very unlikely for getCoreDNSInfo to parse

kcp := kcp.DeepCopy()

kcp.Spec.KubeadmConfigSpec.ClusterConfiguration.DNS.Disabled = true

objs := []client.Object{

cluster.DeepCopy(),

corednsCM.DeepCopy(),

kubeadmCM.DeepCopy(),

depl,

}

sivchari · 2025-06-22T07:56:57Z

controlplane/kubeadm/internal/controllers/controller_test.go

+
+		var actualCoreDNSDeployment appsv1.Deployment
+		g.Expect(fakeClient.Get(ctx, client.ObjectKey{Name: "coredns", Namespace: metav1.NamespaceSystem}, &actualCoreDNSDeployment)).To(Succeed())
+		g.Expect(actualCoreDNSDeployment.Spec.Template.Spec.Containers[0].Image).ToNot(ContainSubstring("coredns"))


Suggested change

g.Expect(actualCoreDNSDeployment.Spec.Template.Spec.Containers[0].Image).ToNot(ContainSubstring("coredns"))

g.Expect(actualCoreDNSDeployment.Spec.Template.Spec.Containers[0].Image).To(Equal("my-cool-image!!!!"))

sivchari · 2025-06-22T07:59:37Z

controlplane/kubeadm/internal/workload_cluster.go

@@ -421,6 +421,12 @@ func staticPodName(component, nodeName string) string {
 func (w *Workload) UpdateKubeProxyImageInfo(ctx context.Context, kcp *controlplanev1.KubeadmControlPlane) error {
 	// Return early if we've been asked to skip kube-proxy upgrades entirely.
 	if _, ok := kcp.Annotations[controlplanev1.SkipKubeProxyAnnotation]; ok {
+		//


Suggested change

//

sivchari · 2025-06-22T08:02:04Z

controlplane/kubeadm/internal/workload_cluster_coredns.go

+	// Return early if DNS is disabled
+	if kcp.Spec.KubeadmConfigSpec.ClusterConfiguration.DNS.Disabled {
+		return nil
+	}
+


Suggested change

// Return early if DNS is disabled

if kcp.Spec.KubeadmConfigSpec.ClusterConfiguration.DNS.Disabled {

return nil

}

// Return early if DNS is disabled

if clusterCondiguration.DNS.Disabled {

return nil

}

We can rewrite it like suggestion when you move these codes after L-94,

See kubernetes-sigs#12288

sathieu · 2025-06-22T21:29:48Z

@fabriziopandini @sivchari Thanks for your review.

@sivchari I've implemented all your suggestions. However, the pointer usage makes code less readable. Should I create helper functions and where?

I've kept the v1beta1 part, because some providers have not yet migrated to v1beta2 (for example capv)

k8s-ci-robot added do-not-merge/work-in-progress Indicates that a PR should not merge because it is a work in progress. area/provider/bootstrap-kubeadm Issues or PRs related to CAPBK cncf-cla: yes Indicates the PR's author has signed the CNCF CLA. labels Jun 13, 2025

k8s-ci-robot requested review from chrischdi and sivchari June 13, 2025 21:11

k8s-ci-robot added needs-ok-to-test Indicates a PR that requires an org member to verify it is safe to test. size/L Denotes a PR that changes 100-499 lines, ignoring generated files. labels Jun 13, 2025

sathieu force-pushed the disable-dns-proxy branch from df65ac9 to d9c128f Compare June 15, 2025 05:38

sathieu marked this pull request as ready for review June 15, 2025 05:39

k8s-ci-robot removed the do-not-merge/work-in-progress Indicates that a PR should not merge because it is a work in progress. label Jun 15, 2025

k8s-ci-robot requested a review from elmiko June 15, 2025 05:39

sathieu force-pushed the disable-dns-proxy branch from d9c128f to 198850a Compare June 15, 2025 05:50

sathieu mentioned this pull request Jun 15, 2025

Review skip Proxy and DNS in KCP and in the KubeadmConfig #12288

Open

sathieu force-pushed the disable-dns-proxy branch from 198850a to 31527e7 Compare June 15, 2025 06:04

sivchari reviewed Jun 22, 2025

View reviewed changes

✨ Allow to disable KubeProxy and CoreDNS

166d792

See kubernetes-sigs#12288

sathieu force-pushed the disable-dns-proxy branch from 31527e7 to 166d792 Compare June 22, 2025 21:27

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		// Disabled specifies whether to disable this addon in the cluster
		Disabled bool `json:"disabled,omitempty"`

	g.Expect(actualCoreDNSDeployment.Spec.Template.Spec.Containers[0].Image).ToNot(ContainSubstring("coredns"))
	g.Expect(actualCoreDNSDeployment.Spec.Template.Spec.Containers[0].Image).To(Equal("my-cool-image!!!!"))

✨ Allow to disable KubeProxy and CoreDNS #12359

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