use kubernetes.io as default label (#97)

Signed-off-by: Felix Breuer <f.breuer94@gmail.com>

Author: breuerfelix

docs/stackit-iaas-api-analysis.md

@@ -213,21 +213,17 @@ Example: `stackit://my-project-123/550e8400-e29b-41d4-a716-446655440000`
 
 Use the `labels` field for MCM identification and mapping:
 
-| Label Key                         | Value             | Purpose                                         |
-| --------------------------------- | ----------------- | ----------------------------------------------- |
-| `mcm.gardener.cloud/cluster`      | Cluster ID        | Identify which cluster owns this server         |
-| `mcm.gardener.cloud/machine`      | Machine CR name   | Map server to Kubernetes Machine                |
-| `mcm.gardener.cloud/machineclass` | MachineClass name | Map server to MachineClass for orphan detection |
-| `mcm.gardener.cloud/role`         | "node"            | Identify as cluster node                        |
+| Label Key                    | Value             | Purpose                                         |
+| ---------------------------- | ----------------- | ----------------------------------------------- |
+| `kubernetes.io/machine`      | Machine CR name   | Map server to Kubernetes Machine                |
+| `kubernetes.io/machineclass` | MachineClass name | Map server to MachineClass for orphan detection |
 
 Example labels:
 
 ```json
 {
-  "mcm.gardener.cloud/cluster": "shoot-dev-01",
-  "mcm.gardener.cloud/machine": "worker-pool-a-12345",
-  "mcm.gardener.cloud/machineclass": "worker-pool-a",
-  "mcm.gardener.cloud/role": "node"
+  "kubernetes.io/machine": "worker-pool-a-12345",
+  "kubernetes.io/machineclass": "worker-pool-a"
 }
 ```
 

pkg/client/sdk_test.go

@@ -116,16 +116,14 @@ var _ = Describe("SDK Type Conversion Helpers", func() {
 
 			It("should convert labels with special characters", func() {
 				labels := map[string]string{
-					"mcm.gardener.cloud/machine": "test-machine",
-					"kubernetes.io/role":         "node",
+					"kubernetes.io/machine": "test-machine",
 				}
 
 				result := convertLabelsToSDK(labels)
 
 				Expect(result).NotTo(BeNil())
 				Expect(result).To(HaveLen(2))
-				Expect(result["mcm.gardener.cloud/machine"]).To(Equal("test-machine"))
-				Expect(result["kubernetes.io/role"]).To(Equal("node"))
+				Expect(result["kubernetes.io/machine"]).To(Equal("test-machine"))
 			})
 		})
 

pkg/provider/apis/validation/validation.go

@@ -38,9 +38,9 @@ var regionRegex = regexp.MustCompile(`^[a-z0-9]+$`)
 // Pattern: lowercase letters/digits followed by digits, dash, then digit(s) (e.g., eu01-1, eu01-2)
 var availabilityZoneRegex = regexp.MustCompile(`^[a-z0-9]+-\d+$`)
 
-// labelKeyRegex validates Kubernetes label keys (must start/end with alphanumeric, can contain -, _, .)
+// labelKeyRegex validates Kubernetes label keys (must start/end with alphanumeric, can contain -, _, ., /)
 // Maximum length: 63 characters
-var labelKeyRegex = regexp.MustCompile(`^[a-zA-Z0-9]([-a-zA-Z0-9_.]*[a-zA-Z0-9])?$`)
+var labelKeyRegex = regexp.MustCompile(`^[a-zA-Z0-9]([-a-zA-Z0-9_./]*[a-zA-Z0-9])?$`)
 
 // labelValueRegex validates Kubernetes label values (must start/end with alphanumeric, can contain -, _, ., can be empty)
 // Maximum length: 63 characters
@@ -113,7 +113,7 @@ func ValidateProviderSpecNSecret(spec *api.ProviderSpec, secrets *corev1.Secret)
 				errors = append(errors, fmt.Errorf("providerSpec.labels key '%s' exceeds maximum length of 63 characters", key))
 			}
 			if !labelKeyRegex.MatchString(key) {
-				errors = append(errors, fmt.Errorf("providerSpec.labels key '%s' has invalid format (must start/end with alphanumeric, can contain -, _, .)", key))
+				errors = append(errors, fmt.Errorf("providerSpec.labels key '%s' has invalid format (must start/end with alphanumeric, can contain -, _, ., /)", key))
 			}
 			if len(value) > 63 {
 				errors = append(errors, fmt.Errorf("providerSpec.labels value for key '%s' exceeds maximum length of 63 characters", key))

pkg/provider/apis/validation/validation_core_labels_test.go

@@ -106,6 +106,7 @@ var _ = Describe("ValidateProviderSpecNSecret", func() {
 				"app.kubernetes.io_component": "worker",
 				"environment-type":            "prod",
 				"version":                     "v1.2.3",
+				"app/component":               "core",
 			}
 			errors := ValidateProviderSpecNSecret(providerSpec, secret)
 			Expect(errors).To(BeEmpty())
@@ -172,6 +173,16 @@ var _ = Describe("ValidateProviderSpecNSecret", func() {
 			Expect(errors[0].Error()).To(ContainSubstring("invalid format"))
 		})
 
+		It("should succeed with label keys containing slashes", func() {
+			providerSpec.Labels = map[string]string{
+				"mycompany.com/environment": "prod",
+				"app.io/version":            "v2",
+				"team/project/name":         "web",
+			}
+			errors := ValidateProviderSpecNSecret(providerSpec, secret)
+			Expect(errors).To(BeEmpty())
+		})
+
 		It("should fail when label key contains invalid characters", func() {
 			providerSpec.Labels = map[string]string{
 				"invalid@key": "value",

pkg/provider/core.go

@@ -11,9 +11,8 @@ import (
 
 const (
 	StackitProviderName      = "stackit"
-	StackitMachineLabel      = "mcm.gardener.cloud/machine"
-	StackitMachineClassLabel = "mcm.gardener.cloud/machineclass"
-	StackitRoleLabel         = "mcm.gardener.cloud/role"
+	StackitMachineLabel      = "kubernetes.io/machine"
+	StackitMachineClassLabel = "kubernetes.io/machineclass"
 )
 
 // GetVolumeIDs extracts volume IDs from PersistentVolume specs

pkg/provider/create.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/base64"
 	"fmt"
+	"maps"
 	"slices"
 
 	"github.com/gardener/machine-controller-manager/pkg/util/provider/driver"
@@ -94,16 +95,15 @@ func (p *Provider) CreateMachine(ctx context.Context, req *driver.CreateMachineR
 func (p *Provider) createServerRequest(req *driver.CreateMachineRequest, providerSpec *api.ProviderSpec) *client.CreateServerRequest {
 	// Build labels: merge ProviderSpec labels with MCM-specific labels
 	labels := make(map[string]string)
+
 	// Start with user-provided labels from ProviderSpec
 	if providerSpec.Labels != nil {
-		for k, v := range providerSpec.Labels {
-			labels[k] = v
-		}
+		maps.Copy(labels, providerSpec.Labels)
 	}
+
 	// Add MCM-specific labels for server identification and orphan VM detection
 	labels[StackitMachineLabel] = req.Machine.Name
 	labels[StackitMachineClassLabel] = req.MachineClass.Name
-	labels[StackitRoleLabel] = "node"
 
 	// Create server request
 	createReq := &client.CreateServerRequest{

pkg/provider/list.go

@@ -13,7 +13,7 @@ import (
 // ListMachines lists all STACKIT servers that belong to the specified MachineClass
 //
 // This method retrieves all servers in the STACKIT project and filters them based on
-// the "mcm.gardener.cloud/machineclass" label. This enables the MCM safety controller
+// the "kubernetes.io/machineclass" label. This enables the MCM safety controller
 // to detect and clean up orphan VMs that are not backed by Machine CRs.
 //
 // Returns:
@@ -51,7 +51,7 @@ func (p *Provider) ListMachines(ctx context.Context, req *driver.ListMachinesReq
 	}
 
 	// Filter servers by MachineClass label
-	// We use the "mcm.gardener.cloud/machineclass" label to identify which servers belong to this MachineClass
+	// We use the "kubernetes.io/machineclass" label to identify which servers belong to this MachineClass
 	machineList := make(map[string]string)
 	for _, server := range servers {
 		// Generate ProviderID in format: stackit://<projectId>/<serverId>

pkg/provider/list_test.go

@@ -71,23 +71,23 @@ var _ = Describe("ListMachines", func() {
 	Context("with valid inputs", func() {
 		It("should list machines filtered by MachineClass label", func() {
 			mockClient.ListServersFunc = func(_ context.Context, _, _ string, selector map[string]string) ([]*client.Server, error) {
-				Expect(selector["mcm.gardener.cloud/machineclass"]).To(Equal("test-machine-class"))
+				Expect(selector["kubernetes.io/machineclass"]).To(Equal("test-machine-class"))
 
 				return []*client.Server{
 					{
 						ID:   "server-1",
 						Name: "machine-1",
 						Labels: map[string]string{
-							"mcm.gardener.cloud/machineclass": "test-machine-class",
-							"mcm.gardener.cloud/machine":      "machine-1",
+							"kubernetes.io/machineclass": "test-machine-class",
+							"kubernetes.io/machine":      "machine-1",
 						},
 					},
 					{
 						ID:   "server-2",
 						Name: "machine-2",
 						Labels: map[string]string{
-							"mcm.gardener.cloud/machineclass": "test-machine-class",
-							"mcm.gardener.cloud/machine":      "machine-2",
+							"kubernetes.io/machineclass": "test-machine-class",
+							"kubernetes.io/machine":      "machine-2",
 						},
 					},
 				}, nil

test/e2e/e2e_labels_test.go

@@ -515,9 +515,8 @@ spec:
 
 			// Verify that MCM-generated labels would still be sent (check provider behavior)
 			// Even without user labels, the provider should add MCM labels like:
-			// - mcm.gardener.cloud/machineclass
-			// - mcm.gardener.cloud/machine
-			// - mcm.gardener.cloud/role
+			// - kubernetes.io/machineclass
+			// - kubernetes.io/machine
 			By("verifying provider handles missing labels gracefully")
 
 			// Check provider logs for any errors related to missing labels