fixup! feat: Support removing all taints

Author: jimmidyson

docs/content/customization/generic/taints.md

@@ -10,6 +10,8 @@ This customization will be available when the
 
 ## Example
 
+### Control plane taints
+
 To configure taints for the control plane nodes, specify the following configuration:
 
 ```yaml
@@ -29,19 +31,39 @@ spec:
                 value: some-value
 ```
 
-{{% alert title="Default control plane taints" color="warning" %}}
+#### Default control-plane taint applied by kubeadm
+
 When using this customization, the default taint added by kubeadm to the control plane nodes will not be added unless
 explicitly specified as well.
 
-To add the default taint to the control-plane, add the following taint along with any custom taints you wish to add to
-the control-plane taints:
+To add the default taint back to the control-plane, add the following taint along with any custom taints you wish to add
+to the control-plane taints:
 
 ```yaml
 - key: node-role.kubernetes.io/control-plane
   effect: NoSchedule
 ```
 
-{{% /alert %}}
+#### Removing all taints from control-plane nodes
+
+To remove the default control plane taints set by kubeadm (and therefore allow scheduling to control plane nodes without
+adding explicit tolerations to your pod manifests), set `controlPlane.taints` to an empty array:
+
+```yaml
+apiVersion: cluster.x-k8s.io/v1beta1
+kind: Cluster
+metadata:
+  name: <NAME>
+spec:
+  topology:
+    variables:
+      - name: clusterConfig
+        value:
+          controlPlane:
+            taints: []
+```
+
+### Worker node taints
 
 Taints for individual nodepools can be configured similarly:
 

pkg/handlers/generic/mutation/taints/inject_controlplane.go

@@ -91,15 +91,13 @@ func (h *taintsControlPlanePatchHandler) Mutate(
 			if obj.Spec.Template.Spec.KubeadmConfigSpec.JoinConfiguration != nil {
 				obj.Spec.Template.Spec.KubeadmConfigSpec.JoinConfiguration = &bootstrapv1.JoinConfiguration{}
 			}
-			coreTaints := toCoreTaints(taintsVar)
-
-			obj.Spec.Template.Spec.KubeadmConfigSpec.InitConfiguration.NodeRegistration.Taints = append(
+			obj.Spec.Template.Spec.KubeadmConfigSpec.InitConfiguration.NodeRegistration.Taints = toCoreTaints(
 				obj.Spec.Template.Spec.KubeadmConfigSpec.InitConfiguration.NodeRegistration.Taints,
-				coreTaints...,
+				taintsVar,
 			)
-			obj.Spec.Template.Spec.KubeadmConfigSpec.JoinConfiguration.NodeRegistration.Taints = append(
+			obj.Spec.Template.Spec.KubeadmConfigSpec.JoinConfiguration.NodeRegistration.Taints = toCoreTaints(
 				obj.Spec.Template.Spec.KubeadmConfigSpec.JoinConfiguration.NodeRegistration.Taints,
-				coreTaints...,
+				taintsVar,
 			)
 
 			return nil

pkg/handlers/generic/mutation/taints/inject_controlplane_test.go

@@ -55,6 +55,33 @@ var _ = Describe("Generate taints patches for Control Plane", func() {
 				),
 			}},
 		},
+		{
+			Name: "taints for control plane set to empty slice to remove default taints",
+			Vars: []runtimehooksv1.Variable{
+				capitest.VariableWithValue(
+					v1alpha1.ClusterConfigVariableName,
+					[]v1alpha1.Taint{},
+					v1alpha1.ControlPlaneConfigVariableName,
+					VariableName,
+				),
+			},
+			RequestItem: request.NewKubeadmControlPlaneTemplateRequestItem(""),
+			ExpectedPatchMatchers: []capitest.JSONPatchMatcher{{
+				Operation: "add",
+				Path:      "/spec/template/spec/kubeadmConfigSpec/initConfiguration/nodeRegistration/taints",
+				ValueMatcher: gomega.SatisfyAll(
+					gomega.Not(gomega.BeNil()),
+					gomega.BeEmpty(),
+				),
+			}, {
+				Operation: "add",
+				Path:      "/spec/template/spec/kubeadmConfigSpec/joinConfiguration/nodeRegistration/taints",
+				ValueMatcher: gomega.SatisfyAll(
+					gomega.Not(gomega.BeNil()),
+					gomega.BeEmpty(),
+				),
+			}},
+		},
 	}
 
 	// create test node for each case

pkg/handlers/generic/mutation/taints/inject_worker.go

@@ -90,20 +90,37 @@ func (h *taintsWorkerPatchHandler) Mutate(
 			if obj.Spec.Template.Spec.JoinConfiguration != nil {
 				obj.Spec.Template.Spec.JoinConfiguration = &bootstrapv1.JoinConfiguration{}
 			}
-			obj.Spec.Template.Spec.JoinConfiguration.NodeRegistration.Taints = append(
+			obj.Spec.Template.Spec.JoinConfiguration.NodeRegistration.Taints = toCoreTaints(
 				obj.Spec.Template.Spec.JoinConfiguration.NodeRegistration.Taints,
-				toCoreTaints(taintsVar)...,
+				taintsVar,
 			)
 			return nil
 		})
 }
 
-func toCoreTaints(taints []v1alpha1.Taint) []v1.Taint {
-	return lo.Map(taints, func(t v1alpha1.Taint, _ int) v1.Taint {
-		return v1.Taint{
-			Key:    t.Key,
-			Effect: v1.TaintEffect(t.Effect),
-			Value:  t.Value,
-		}
-	})
+func toCoreTaints(existingTaints []v1.Taint, newTaints []v1alpha1.Taint) []v1.Taint {
+	var newCoreTaints []v1.Taint
+	// Only initialize newCoreTaints if newTaints is not nil otherwise not setting the value at all will
+	// end up with an empty (but initialized) slice which will remove all taints, which is not the desired behavior.
+	if newTaints != nil {
+		newCoreTaints = lo.Map(newTaints, func(t v1alpha1.Taint, _ int) v1.Taint {
+			return v1.Taint{
+				Key:    t.Key,
+				Effect: v1.TaintEffect(t.Effect),
+				Value:  t.Value,
+			}
+		})
+	}
+
+	switch {
+	// If no new taints then return existing taints.
+	case newTaints == nil:
+		return existingTaints
+	// If no existing taints then return new taints.
+	case existingTaints == nil:
+		return newCoreTaints
+	// If both existing and new taints are present then append new taints to existing taints.
+	default:
+		return append(existingTaints, newCoreTaints...)
+	}
 }