⚠️ Change type of *string fields with invalid zero value to string

api/bootstrap/kubeadm/v1beta1/conversion.go

@@ -262,6 +262,9 @@ func (dst *KubeadmConfig) ConvertFrom(srcRaw conversion.Hub) error {
 	// Convert timeouts moved from one struct to another.
 	dst.Spec.ConvertFrom(&src.Spec)
 
+	dropEmptyStringsKubeadmConfigSpec(&dst.Spec)
+	dropEmptyStringsKubeadmConfigStatus(&dst.Status)
+
 	// Preserve Hub data on down-conversion except for metadata.
 	return utilconversion.MarshalData(src, dst)
 }
@@ -324,6 +327,8 @@ func (dst *KubeadmConfigTemplate) ConvertFrom(srcRaw conversion.Hub) error {
 	// Convert timeouts moved from one struct to another.
 	dst.Spec.Template.Spec.ConvertFrom(&src.Spec.Template.Spec)
 
+	dropEmptyStringsKubeadmConfigSpec(&dst.Spec.Template.Spec)
+
 	// Preserve Hub data on down-conversion except for metadata.
 	return utilconversion.MarshalData(src, dst)
 }
@@ -494,3 +499,38 @@ func Convert_v1_Condition_To_v1beta1_Condition(in *metav1.Condition, out *cluste
 func Convert_v1beta1_Condition_To_v1_Condition(in *clusterv1beta1.Condition, out *metav1.Condition, s apimachineryconversion.Scope) error {
 	return clusterv1beta1.Convert_v1beta1_Condition_To_v1_Condition(in, out, s)
 }
+
+func dropEmptyStringsKubeadmConfigSpec(dst *KubeadmConfigSpec) {
+	for i, u := range dst.Users {
+		dropEmptyString(&u.Gecos)
+		dropEmptyString(&u.Groups)
+		dropEmptyString(&u.HomeDir)
+		dropEmptyString(&u.Shell)
+		dropEmptyString(&u.Passwd)
+		dropEmptyString(&u.PrimaryGroup)
+		dropEmptyString(&u.Sudo)
+		dst.Users[i] = u
+	}
+
+	if dst.DiskSetup != nil {
+		for i, p := range dst.DiskSetup.Partitions {
+			dropEmptyString(&p.TableType)
+			dst.DiskSetup.Partitions[i] = p
+		}
+		for i, f := range dst.DiskSetup.Filesystems {
+			dropEmptyString(&f.Partition)
+			dropEmptyString(&f.ReplaceFS)
+			dst.DiskSetup.Filesystems[i] = f
+		}
+	}
+}
+
+func dropEmptyStringsKubeadmConfigStatus(dst *KubeadmConfigStatus) {
+	dropEmptyString(&dst.DataSecretName)
+}
+
+func dropEmptyString(s **string) {
+	if *s != nil && **s == "" {
+		*s = nil
+	}
+}

api/bootstrap/kubeadm/v1beta1/conversion_test.go

@@ -133,6 +133,8 @@ func spokeKubeadmConfigSpec(in *KubeadmConfigSpec, c randfill.Continue) {
 
 	// Drop UseExperimentalRetryJoin as we intentionally don't preserve it.
 	in.UseExperimentalRetryJoin = false
+
+	dropEmptyStringsKubeadmConfigSpec(in)
 }
 
 func spokeClusterConfiguration(in *ClusterConfiguration, c randfill.Continue) {
@@ -178,4 +180,6 @@ func spokeKubeadmConfigStatus(in *KubeadmConfigStatus, c randfill.Continue) {
 			in.V1Beta2 = nil
 		}
 	}
+
+	dropEmptyStringsKubeadmConfigStatus(in)
 }