restrict machine deployment topology name to less than 63 characters

internal/topology/check/compatibility.go

@@ -23,6 +23,7 @@ import (
 
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/util/sets"
+	"k8s.io/apimachinery/pkg/util/validation"
 	"k8s.io/apimachinery/pkg/util/validation/field"
 	"sigs.k8s.io/controller-runtime/pkg/client"
 
@@ -277,6 +278,19 @@ func MachineDeploymentTopologiesAreValidAndDefinedInClusterClass(desired *cluste
 	machineDeploymentClasses := classNamesFromWorkerClass(clusterClass.Spec.Workers)
 	names := sets.String{}
 	for i, md := range desired.Spec.Topology.Workers.MachineDeployments {
+		if errs := validation.IsValidLabelValue(md.Name); len(errs) != 0 {
+			for _, err := range errs {
+				allErrs = append(
+					allErrs,
+					field.Invalid(
+						field.NewPath("spec", "topology", "workers", "machineDeployments").Index(i).Child("name"),
+						md.Name,
+						fmt.Sprintf("must be a valid label value %s", err),
+					),
+				)
+			}
+		}
+
 		if !machineDeploymentClasses.Has(md.Class) {
 			allErrs = append(allErrs,
 				field.Invalid(

internal/topology/check/compatibility_test.go

@@ -992,6 +992,36 @@ func TestMachineDeploymentTopologiesAreUniqueAndDefinedInClusterClass(t *testing
 				Build(),
 			wantErr: false,
 		},
+		{
+			name: "fail if MachineDeploymentTopology name is longer than 63 characters",
+			clusterClass: builder.ClusterClass(metav1.NamespaceDefault, "class1").
+				WithInfrastructureClusterTemplate(
+					builder.InfrastructureClusterTemplate(metav1.NamespaceDefault, "infra1").Build()).
+				WithControlPlaneTemplate(
+					builder.ControlPlane(metav1.NamespaceDefault, "cp1").Build()).
+				WithControlPlaneInfrastructureMachineTemplate(
+					builder.InfrastructureMachineTemplate(metav1.NamespaceDefault, "cpinfra1").Build()).
+				WithWorkerMachineDeploymentClasses(
+					*builder.MachineDeploymentClass("aa").
+						WithInfrastructureTemplate(
+							builder.InfrastructureMachineTemplate(metav1.NamespaceDefault, "infra1").Build()).
+						WithBootstrapTemplate(
+							builder.BootstrapTemplate(metav1.NamespaceDefault, "bootstrap1").Build()).
+						Build()).
+				Build(),
+			cluster: builder.Cluster(metav1.NamespaceDefault, "cluster1").
+				WithTopology(
+					builder.ClusterTopology().
+						WithClass("class1").
+						WithVersion("v1.22.2").
+						WithMachineDeployment(
+							builder.MachineDeploymentTopology("machine-deployment-topology-name-that-has-longerthan63characterlooooooooooooooooooooooongname").
+								WithClass("aa").
+								Build()).
+						Build()).
+				Build(),
+			wantErr: true,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {