Enforce unique subnet names

Author: Cecile Robert-Michon

api/v1alpha3/azurecluster_validation.go

@@ -84,14 +84,20 @@ func validateResourceGroup(resourceGroup string, fldPath *field.Path) *field.Err
 // validateSubnets validates a list of Subnets
 func validateSubnets(subnets Subnets, fldPath *field.Path) field.ErrorList {
 	var allErrs field.ErrorList
+	subnetNames := make(map[string]bool, len(subnets))
 	requiredSubnetRoles := map[string]bool{
 		"control-plane": false,
 		"node":          false,
 	}
+
 	for i, subnet := range subnets {
 		if err := validateSubnetName(subnet.Name, fldPath.Index(i).Child("name")); err != nil {
 			allErrs = append(allErrs, err)
 		}
+		if _, ok := subnetNames[subnet.Name]; ok {
+			allErrs = append(allErrs, field.Duplicate(fldPath, subnet.Name))
+		}
+		subnetNames[subnet.Name] = true
 		if subnet.InternalLBIPAddress != "" {
 			if err := validateInternalLBIPAddress(subnet.InternalLBIPAddress,
 				fldPath.Index(i).Child("internalLBIPAddress")); err != nil {

api/v1alpha3/azurecluster_validation_test.go

@@ -384,6 +384,31 @@ func TestSubnetsInvalidLackRequiredSubnet(t *testing.T) {
 	})
 }
 
+func TestSubnetNamesNotUnique(t *testing.T) {
+	g := NewWithT(t)
+
+	type test struct {
+		name    string
+		subnets Subnets
+	}
+
+	testCase := test{
+		name:    "subnets - names not unique",
+		subnets: createValidSubnets(),
+	}
+
+	testCase.subnets[0].Name = "subnet-name"
+	testCase.subnets[1].Name = "subnet-name"
+
+	t.Run(testCase.name, func(t *testing.T) {
+		errs := validateSubnets(testCase.subnets,
+			field.NewPath("spec").Child("networkSpec").Child("subnets"))
+		g.Expect(errs).To(HaveLen(1))
+		g.Expect(errs[0].Type).To(Equal(field.ErrorTypeDuplicate))
+		g.Expect(errs[0].Field).To(Equal("spec.networkSpec.subnets"))
+	})
+}
+
 func TestSubnetNameValid(t *testing.T) {
 	g := NewWithT(t)