cmd/k8s-operator,k8s-operator: allow users to set custom labels for the optional ServiceMonitor (#14475)

* cmd/k8s-operator,k8s-operator: allow users to set custom labels for the optional ServiceMonitor

Updates tailscale/tailscale#14381

Signed-off-by: Irbe Krumina <irbe@tailscale.com>

cmd/k8s-operator/connector_test.go

@@ -203,7 +203,7 @@ func TestConnectorWithProxyClass(t *testing.T) {
 	pc := &tsapi.ProxyClass{
 		ObjectMeta: metav1.ObjectMeta{Name: "custom-metadata"},
 		Spec: tsapi.ProxyClassSpec{StatefulSet: &tsapi.StatefulSet{
-			Labels:      map[string]string{"foo": "bar"},
+			Labels:      tsapi.Labels{"foo": "bar"},
 			Annotations: map[string]string{"bar.io/foo": "some-val"},
 			Pod:         &tsapi.Pod{Annotations: map[string]string{"foo.io/bar": "some-val"}}}},
 	}

cmd/k8s-operator/deploy/crds/tailscale.com_proxyclasses.yaml

@@ -99,6 +99,16 @@ spec:
                         enable:
                           description: If Enable is set to true, a Prometheus ServiceMonitor will be created. Enable can only be set to true if metrics are enabled.
                           type: boolean
+                        labels:
+                          description: |-
+                            Labels to add to the ServiceMonitor.
+                            Labels must be valid Kubernetes labels.
+                            https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#syntax-and-character-set
+                          type: object
+                          additionalProperties:
+                            type: string
+                            maxLength: 63
+                            pattern: ^(([a-zA-Z0-9][-._a-zA-Z0-9]*)?[a-zA-Z0-9])?$
                   x-kubernetes-validations:
                     - rule: '!(has(self.serviceMonitor) && self.serviceMonitor.enable  && !self.enable)'
                       message: ServiceMonitor can only be enabled if metrics are enabled
@@ -133,6 +143,8 @@ spec:
                       type: object
                       additionalProperties:
                         type: string
+                        maxLength: 63
+                        pattern: ^(([a-zA-Z0-9][-._a-zA-Z0-9]*)?[a-zA-Z0-9])?$
                     pod:
                       description: Configuration for the proxy Pod.
                       type: object
@@ -1062,6 +1074,8 @@ spec:
                           type: object
                           additionalProperties:
                             type: string
+                            maxLength: 63
+                            pattern: ^(([a-zA-Z0-9][-._a-zA-Z0-9]*)?[a-zA-Z0-9])?$
                         nodeName:
                           description: |-
                             Proxy Pod's node name.

cmd/k8s-operator/deploy/manifests/operator.yaml

@@ -563,6 +563,16 @@ spec:
                                             enable:
                                                 description: If Enable is set to true, a Prometheus ServiceMonitor will be created. Enable can only be set to true if metrics are enabled.
                                                 type: boolean
+                                            labels:
+                                                additionalProperties:
+                                                    maxLength: 63
+                                                    pattern: ^(([a-zA-Z0-9][-._a-zA-Z0-9]*)?[a-zA-Z0-9])?$
+                                                    type: string
+                                                description: |-
+                                                    Labels to add to the ServiceMonitor.
+                                                    Labels must be valid Kubernetes labels.
+                                                    https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#syntax-and-character-set
+                                                type: object
                                         required:
                                             - enable
                                         type: object
@@ -592,6 +602,8 @@ spec:
                                         type: object
                                     labels:
                                         additionalProperties:
+                                            maxLength: 63
+                                            pattern: ^(([a-zA-Z0-9][-._a-zA-Z0-9]*)?[a-zA-Z0-9])?$
                                             type: string
                                         description: |-
                                             Labels that will be added to the StatefulSet created for the proxy.
@@ -1522,6 +1534,8 @@ spec:
                                                 type: array
                                             labels:
                                                 additionalProperties:
+                                                    maxLength: 63
+                                                    pattern: ^(([a-zA-Z0-9][-._a-zA-Z0-9]*)?[a-zA-Z0-9])?$
                                                     type: string
                                                 description: |-
                                                     Labels that will be added to the proxy Pod.

cmd/k8s-operator/ingress_test.go

@@ -295,7 +295,7 @@ func TestTailscaleIngressWithProxyClass(t *testing.T) {
 	pc := &tsapi.ProxyClass{
 		ObjectMeta: metav1.ObjectMeta{Name: "custom-metadata"},
 		Spec: tsapi.ProxyClassSpec{StatefulSet: &tsapi.StatefulSet{
-			Labels:      map[string]string{"foo": "bar"},
+			Labels:      tsapi.Labels{"foo": "bar"},
 			Annotations: map[string]string{"bar.io/foo": "some-val"},
 			Pod:         &tsapi.Pod{Annotations: map[string]string{"foo.io/bar": "some-val"}}}},
 	}
@@ -424,12 +424,7 @@ func TestTailscaleIngressWithProxyClass(t *testing.T) {
 func TestTailscaleIngressWithServiceMonitor(t *testing.T) {
 	pc := &tsapi.ProxyClass{
 		ObjectMeta: metav1.ObjectMeta{Name: "metrics", Generation: 1},
-		Spec: tsapi.ProxyClassSpec{
-			Metrics: &tsapi.Metrics{
-				Enable:         true,
-				ServiceMonitor: &tsapi.ServiceMonitor{Enable: true},
-			},
-		},
+		Spec:       tsapi.ProxyClassSpec{},
 		Status: tsapi.ProxyClassStatus{
 			Conditions: []metav1.Condition{{
 				Status:             metav1.ConditionTrue,
@@ -437,32 +432,6 @@ func TestTailscaleIngressWithServiceMonitor(t *testing.T) {
 				ObservedGeneration: 1,
 			}}},
 	}
-	crd := &apiextensionsv1.CustomResourceDefinition{ObjectMeta: metav1.ObjectMeta{Name: serviceMonitorCRD}}
-	tsIngressClass := &networkingv1.IngressClass{ObjectMeta: metav1.ObjectMeta{Name: "tailscale"}, Spec: networkingv1.IngressClassSpec{Controller: "tailscale.com/ts-ingress"}}
-	fc := fake.NewClientBuilder().
-		WithScheme(tsapi.GlobalScheme).
-		WithObjects(pc, tsIngressClass).
-		WithStatusSubresource(pc).
-		Build()
-	ft := &fakeTSClient{}
-	fakeTsnetServer := &fakeTSNetServer{certDomains: []string{"foo.com"}}
-	zl, err := zap.NewDevelopment()
-	if err != nil {
-		t.Fatal(err)
-	}
-	ingR := &IngressReconciler{
-		Client: fc,
-		ssr: &tailscaleSTSReconciler{
-			Client:            fc,
-			tsClient:          ft,
-			tsnetServer:       fakeTsnetServer,
-			defaultTags:       []string{"tag:k8s"},
-			operatorNamespace: "operator-ns",
-			proxyImage:        "tailscale/tailscale",
-		},
-		logger: zl.Sugar(),
-	}
-	// 1. Enable metrics- expect metrics Service to be created
 	ing := &networkingv1.Ingress{
 		TypeMeta: metav1.TypeMeta{Kind: "Ingress", APIVersion: "networking.k8s.io/v1"},
 		ObjectMeta: metav1.ObjectMeta{
@@ -491,8 +460,7 @@ func TestTailscaleIngressWithServiceMonitor(t *testing.T) {
 			},
 		},
 	}
-	mustCreate(t, fc, ing)
-	mustCreate(t, fc, &corev1.Service{
+	svc := &corev1.Service{
 		ObjectMeta: metav1.ObjectMeta{
 			Name:      "test",
 			Namespace: "default",
@@ -504,11 +472,38 @@ func TestTailscaleIngressWithServiceMonitor(t *testing.T) {
 				Name: "http"},
 			},
 		},
-	})
-
+	}
+	crd := &apiextensionsv1.CustomResourceDefinition{ObjectMeta: metav1.ObjectMeta{Name: serviceMonitorCRD}}
+	tsIngressClass := &networkingv1.IngressClass{ObjectMeta: metav1.ObjectMeta{Name: "tailscale"}, Spec: networkingv1.IngressClassSpec{Controller: "tailscale.com/ts-ingress"}}
+	fc := fake.NewClientBuilder().
+		WithScheme(tsapi.GlobalScheme).
+		WithObjects(pc, tsIngressClass, ing, svc).
+		WithStatusSubresource(pc).
+		Build()
+	ft := &fakeTSClient{}
+	fakeTsnetServer := &fakeTSNetServer{certDomains: []string{"foo.com"}}
+	zl, err := zap.NewDevelopment()
+	if err != nil {
+		t.Fatal(err)
+	}
+	ingR := &IngressReconciler{
+		Client: fc,
+		ssr: &tailscaleSTSReconciler{
+			Client:            fc,
+			tsClient:          ft,
+			tsnetServer:       fakeTsnetServer,
+			defaultTags:       []string{"tag:k8s"},
+			operatorNamespace: "operator-ns",
+			proxyImage:        "tailscale/tailscale",
+		},
+		logger: zl.Sugar(),
+	}
 	expectReconciled(t, ingR, "default", "test")
-
 	fullName, shortName := findGenName(t, fc, "default", "test", "ingress")
+	serveConfig := &ipn.ServeConfig{
+		TCP: map[uint16]*ipn.TCPPortHandler{443: {HTTPS: true}},
+		Web: map[ipn.HostPort]*ipn.WebServerConfig{"${TS_CERT_DOMAIN}:443": {Handlers: map[string]*ipn.HTTPHandler{"/": {Proxy: "http://1.2.3.4:8080/"}}}},
+	}
 	opts := configOpts{
 		stsName:            shortName,
 		secretName:         fullName,
@@ -517,27 +512,51 @@ func TestTailscaleIngressWithServiceMonitor(t *testing.T) {
 		parentType:         "ingress",
 		hostname:           "default-test",
 		app:                kubetypes.AppIngressResource,
-		enableMetrics:      true,
 		namespaced:         true,
 		proxyType:          proxyTypeIngressResource,
+		serveConfig:        serveConfig,
+		resourceVersion:    "1",
 	}
-	serveConfig := &ipn.ServeConfig{
-		TCP: map[uint16]*ipn.TCPPortHandler{443: {HTTPS: true}},
-		Web: map[ipn.HostPort]*ipn.WebServerConfig{"${TS_CERT_DOMAIN}:443": {Handlers: map[string]*ipn.HTTPHandler{"/": {Proxy: "http://1.2.3.4:8080/"}}}},
-	}
-	opts.serveConfig = serveConfig
 
-	expectEqual(t, fc, expectedSecret(t, fc, opts), nil)
-	expectEqual(t, fc, expectedHeadlessService(shortName, "ingress"), nil)
+	// 1. Enable metrics- expect metrics Service to be created
+	mustUpdate(t, fc, "", "metrics", func(proxyClass *tsapi.ProxyClass) {
+		proxyClass.Spec.Metrics = &tsapi.Metrics{Enable: true}
+	})
+	opts.enableMetrics = true
+
+	expectReconciled(t, ingR, "default", "test")
+
 	expectEqual(t, fc, expectedMetricsService(opts), nil)
-	expectEqual(t, fc, expectedSTSUserspace(t, fc, opts), removeHashAnnotation)
+
 	// 2. Enable ServiceMonitor - should not error when there is no ServiceMonitor CRD in cluster
 	mustUpdate(t, fc, "", "metrics", func(pc *tsapi.ProxyClass) {
-		pc.Spec.Metrics.ServiceMonitor = &tsapi.ServiceMonitor{Enable: true}
+		pc.Spec.Metrics.ServiceMonitor = &tsapi.ServiceMonitor{Enable: true, Labels: tsapi.Labels{"foo": "bar"}}
 	})
 	expectReconciled(t, ingR, "default", "test")
+	expectEqual(t, fc, expectedMetricsService(opts), nil)
+
 	// 3. Create ServiceMonitor CRD and reconcile- ServiceMonitor should get created
 	mustCreate(t, fc, crd)
 	expectReconciled(t, ingR, "default", "test")
+	opts.serviceMonitorLabels = tsapi.Labels{"foo": "bar"}
+	expectEqual(t, fc, expectedMetricsService(opts), nil)
+	expectEqualUnstructured(t, fc, expectedServiceMonitor(t, opts))
+
+	// 4. Update ServiceMonitor CRD and reconcile- ServiceMonitor should get updated
+	mustUpdate(t, fc, pc.Namespace, pc.Name, func(proxyClass *tsapi.ProxyClass) {
+		proxyClass.Spec.Metrics.ServiceMonitor.Labels = nil
+	})
+	expectReconciled(t, ingR, "default", "test")
+	opts.serviceMonitorLabels = nil
+	opts.resourceVersion = "2"
+	expectEqual(t, fc, expectedMetricsService(opts), nil)
 	expectEqualUnstructured(t, fc, expectedServiceMonitor(t, opts))
+
+	// 5. Disable metrics - metrics resources should get deleted.
+	mustUpdate(t, fc, pc.Namespace, pc.Name, func(proxyClass *tsapi.ProxyClass) {
+		proxyClass.Spec.Metrics = nil
+	})
+	expectReconciled(t, ingR, "default", "test")
+	expectMissing[corev1.Service](t, fc, "operator-ns", metricsResourceName(shortName))
+	// ServiceMonitor gets garbage collected when the Service is deleted - we cannot test that here.
 }

cmd/k8s-operator/metrics_resources.go

@@ -8,6 +8,7 @@ package main
 import (
 	"context"
 	"fmt"
+	"reflect"
 
 	"go.uber.org/zap"
 	corev1 "k8s.io/api/core/v1"
@@ -115,15 +116,15 @@ func reconcileMetricsResources(ctx context.Context, logger *zap.SugaredLogger, o
 		return maybeCleanupServiceMonitor(ctx, cl, opts.proxyStsName, opts.tsNamespace)
 	}
 
-	logger.Info("ensuring ServiceMonitor for metrics Service %s/%s", metricsSvc.Namespace, metricsSvc.Name)
-	svcMonitor, err := newServiceMonitor(metricsSvc)
+	logger.Infof("ensuring ServiceMonitor for metrics Service %s/%s", metricsSvc.Namespace, metricsSvc.Name)
+	svcMonitor, err := newServiceMonitor(metricsSvc, pc.Spec.Metrics.ServiceMonitor)
 	if err != nil {
 		return fmt.Errorf("error creating ServiceMonitor: %w", err)
 	}
-	// We don't use createOrUpdate here because that does not work with unstructured types. We also do not update
-	// the ServiceMonitor because it is not expected that any of its fields would change. Currently this is good
-	// enough, but in future we might want to add logic to create-or-update unstructured types.
-	err = cl.Get(ctx, client.ObjectKeyFromObject(metricsSvc), svcMonitor.DeepCopy())
+
+	// We don't use createOrUpdate here because that does not work with unstructured types.
+	existing := svcMonitor.DeepCopy()
+	err = cl.Get(ctx, client.ObjectKeyFromObject(metricsSvc), existing)
 	if apierrors.IsNotFound(err) {
 		if err := cl.Create(ctx, svcMonitor); err != nil {
 			return fmt.Errorf("error creating ServiceMonitor: %w", err)
@@ -133,6 +134,13 @@ func reconcileMetricsResources(ctx context.Context, logger *zap.SugaredLogger, o
 	if err != nil {
 		return fmt.Errorf("error getting ServiceMonitor: %w", err)
 	}
+	// Currently, we only update labels on the ServiceMonitor as those are the only values that can change.
+	if !reflect.DeepEqual(existing.GetLabels(), svcMonitor.GetLabels()) {
+		existing.SetLabels(svcMonitor.GetLabels())
+		if err := cl.Update(ctx, existing); err != nil {
+			return fmt.Errorf("error updating ServiceMonitor: %w", err)
+		}
+	}
 	return nil
 }
 
@@ -165,9 +173,13 @@ func maybeCleanupServiceMonitor(ctx context.Context, cl client.Client, stsName,
 // newServiceMonitor takes a metrics Service created for a proxy and constructs and returns a ServiceMonitor for that
 // proxy that can be applied to the kube API server.
 // The ServiceMonitor is returned as Unstructured type - this allows us to avoid importing prometheus-operator API server client/schema.
-func newServiceMonitor(metricsSvc *corev1.Service) (*unstructured.Unstructured, error) {
+func newServiceMonitor(metricsSvc *corev1.Service, spec *tsapi.ServiceMonitor) (*unstructured.Unstructured, error) {
 	sm := serviceMonitorTemplate(metricsSvc.Name, metricsSvc.Namespace)
 	sm.ObjectMeta.Labels = metricsSvc.Labels
+	if spec != nil && len(spec.Labels) > 0 {
+		sm.ObjectMeta.Labels = mergeMapKeys(sm.ObjectMeta.Labels, spec.Labels.Parse())
+	}
+
 	sm.ObjectMeta.OwnerReferences = []metav1.OwnerReference{*metav1.NewControllerRef(metricsSvc, corev1.SchemeGroupVersion.WithKind("Service"))}
 	sm.Spec = ServiceMonitorSpec{
 		Selector: metav1.LabelSelector{MatchLabels: metricsSvc.Labels},
@@ -270,3 +282,14 @@ type metricsOpts struct {
 func isNamespacedProxyType(typ string) bool {
 	return typ == proxyTypeIngressResource || typ == proxyTypeIngressService
 }
+
+func mergeMapKeys(a, b map[string]string) map[string]string {
+	m := make(map[string]string, len(a)+len(b))
+	for key, val := range b {
+		m[key] = val
+	}
+	for key, val := range a {
+		m[key] = val
+	}
+	return m
+}

cmd/k8s-operator/operator_test.go

@@ -16,6 +16,7 @@ import (
 	appsv1 "k8s.io/api/apps/v1"
 	corev1 "k8s.io/api/core/v1"
 	networkingv1 "k8s.io/api/networking/v1"
+	apiextensionsv1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/client-go/tools/record"
@@ -1129,7 +1130,7 @@ func TestProxyClassForService(t *testing.T) {
 				AcceptRoutes: true,
 			},
 			StatefulSet: &tsapi.StatefulSet{
-				Labels:      map[string]string{"foo": "bar"},
+				Labels:      tsapi.Labels{"foo": "bar"},
 				Annotations: map[string]string{"bar.io/foo": "some-val"},
 				Pod:         &tsapi.Pod{Annotations: map[string]string{"foo.io/bar": "some-val"}}}},
 	}
@@ -1766,6 +1767,106 @@ func Test_externalNameService(t *testing.T) {
 	expectEqual(t, fc, expectedSTS(t, fc, opts), removeHashAnnotation)
 }
 
+func Test_metricsResourceCreation(t *testing.T) {
+	pc := &tsapi.ProxyClass{
+		ObjectMeta: metav1.ObjectMeta{Name: "metrics", Generation: 1},
+		Spec:       tsapi.ProxyClassSpec{},
+		Status: tsapi.ProxyClassStatus{
+			Conditions: []metav1.Condition{{
+				Status:             metav1.ConditionTrue,
+				Type:               string(tsapi.ProxyClassReady),
+				ObservedGeneration: 1,
+			}}},
+	}
+	svc := &corev1.Service{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:      "test",
+			Namespace: "default",
+			UID:       types.UID("1234-UID"),
+			Labels:    map[string]string{LabelProxyClass: "metrics"},
+		},
+		Spec: corev1.ServiceSpec{
+			ClusterIP:         "10.20.30.40",
+			Type:              corev1.ServiceTypeLoadBalancer,
+			LoadBalancerClass: ptr.To("tailscale"),
+		},
+	}
+	crd := &apiextensionsv1.CustomResourceDefinition{ObjectMeta: metav1.ObjectMeta{Name: serviceMonitorCRD}}
+	fc := fake.NewClientBuilder().
+		WithScheme(tsapi.GlobalScheme).
+		WithObjects(pc, svc).
+		WithStatusSubresource(pc).
+		Build()
+	ft := &fakeTSClient{}
+	zl, err := zap.NewDevelopment()
+	if err != nil {
+		t.Fatal(err)
+	}
+	clock := tstest.NewClock(tstest.ClockOpts{})
+	sr := &ServiceReconciler{
+		Client: fc,
+		ssr: &tailscaleSTSReconciler{
+			Client:            fc,
+			tsClient:          ft,
+			operatorNamespace: "operator-ns",
+		},
+		logger: zl.Sugar(),
+		clock:  clock,
+	}
+	expectReconciled(t, sr, "default", "test")
+	fullName, shortName := findGenName(t, fc, "default", "test", "svc")
+	opts := configOpts{
+		stsName:            shortName,
+		secretName:         fullName,
+		namespace:          "default",
+		parentType:         "svc",
+		tailscaleNamespace: "operator-ns",
+		hostname:           "default-test",
+		namespaced:         true,
+		proxyType:          proxyTypeIngressService,
+		app:                kubetypes.AppIngressProxy,
+		resourceVersion:    "1",
+	}
+
+	// 1. Enable metrics- expect metrics Service to be created
+	mustUpdate(t, fc, "", "metrics", func(pc *tsapi.ProxyClass) {
+		pc.Spec = tsapi.ProxyClassSpec{Metrics: &tsapi.Metrics{Enable: true}}
+	})
+	expectReconciled(t, sr, "default", "test")
+	opts.enableMetrics = true
+	expectEqual(t, fc, expectedMetricsService(opts), nil)
+
+	// 2. Enable ServiceMonitor - should not error when there is no ServiceMonitor CRD in cluster
+	mustUpdate(t, fc, "", "metrics", func(pc *tsapi.ProxyClass) {
+		pc.Spec.Metrics.ServiceMonitor = &tsapi.ServiceMonitor{Enable: true}
+	})
+	expectReconciled(t, sr, "default", "test")
+
+	// 3. Create ServiceMonitor CRD and reconcile- ServiceMonitor should get created
+	mustCreate(t, fc, crd)
+	expectReconciled(t, sr, "default", "test")
+	expectEqualUnstructured(t, fc, expectedServiceMonitor(t, opts))
+
+	// 4. A change to ServiceMonitor config gets reflected in the ServiceMonitor resource
+	mustUpdate(t, fc, "", "metrics", func(pc *tsapi.ProxyClass) {
+		pc.Spec.Metrics.ServiceMonitor.Labels = tsapi.Labels{"foo": "bar"}
+	})
+	expectReconciled(t, sr, "default", "test")
+	opts.serviceMonitorLabels = tsapi.Labels{"foo": "bar"}
+	opts.resourceVersion = "2"
+	expectEqual(t, fc, expectedMetricsService(opts), nil)
+	expectEqualUnstructured(t, fc, expectedServiceMonitor(t, opts))
+
+	// 5. Disable metrics- expect metrics Service to be deleted
+	mustUpdate(t, fc, "", "metrics", func(pc *tsapi.ProxyClass) {
+		pc.Spec.Metrics = nil
+	})
+	expectReconciled(t, sr, "default", "test")
+	expectMissing[corev1.Service](t, fc, "operator-ns", metricsResourceName(opts.stsName))
+	// ServiceMonitor gets garbage collected when Service gets deleted (it has OwnerReference of the Service
+	// object). We cannot test this using the fake client.
+}
+
 func toFQDN(t *testing.T, s string) dnsname.FQDN {
 	t.Helper()
 	fqdn, err := dnsname.ToFQDN(s)

cmd/k8s-operator/proxyclass.go

@@ -115,7 +115,7 @@ func (pcr *ProxyClassReconciler) Reconcile(ctx context.Context, req reconcile.Re
 func (pcr *ProxyClassReconciler) validate(ctx context.Context, pc *tsapi.ProxyClass) (violations field.ErrorList) {
 	if sts := pc.Spec.StatefulSet; sts != nil {
 		if len(sts.Labels) > 0 {
-			if errs := metavalidation.ValidateLabels(sts.Labels, field.NewPath(".spec.statefulSet.labels")); errs != nil {
+			if errs := metavalidation.ValidateLabels(sts.Labels.Parse(), field.NewPath(".spec.statefulSet.labels")); errs != nil {
 				violations = append(violations, errs...)
 			}
 		}
@@ -126,7 +126,7 @@ func (pcr *ProxyClassReconciler) validate(ctx context.Context, pc *tsapi.ProxyCl
 		}
 		if pod := sts.Pod; pod != nil {
 			if len(pod.Labels) > 0 {
-				if errs := metavalidation.ValidateLabels(pod.Labels, field.NewPath(".spec.statefulSet.pod.labels")); errs != nil {
+				if errs := metavalidation.ValidateLabels(pod.Labels.Parse(), field.NewPath(".spec.statefulSet.pod.labels")); errs != nil {
 					violations = append(violations, errs...)
 				}
 			}
@@ -178,6 +178,11 @@ func (pcr *ProxyClassReconciler) validate(ctx context.Context, pc *tsapi.ProxyCl
 			violations = append(violations, field.TypeInvalid(field.NewPath("spec", "metrics", "serviceMonitor"), "enable", msg))
 		}
 	}
+	if pc.Spec.Metrics != nil && pc.Spec.Metrics.ServiceMonitor != nil && len(pc.Spec.Metrics.ServiceMonitor.Labels) > 0 {
+		if errs := metavalidation.ValidateLabels(pc.Spec.Metrics.ServiceMonitor.Labels.Parse(), field.NewPath(".spec.metrics.serviceMonitor.labels")); errs != nil {
+			violations = append(violations, errs...)
+		}
+	}
 	// We do not validate embedded fields (security context, resource
 	// requirements etc) as we inherit upstream validation for those fields.
 	// Invalid values would get rejected by upstream validations at apply

cmd/k8s-operator/proxyclass_test.go

@@ -36,10 +36,10 @@ func TestProxyClass(t *testing.T) {
 		},
 		Spec: tsapi.ProxyClassSpec{
 			StatefulSet: &tsapi.StatefulSet{
-				Labels:      map[string]string{"foo": "bar", "xyz1234": "abc567"},
+				Labels:      tsapi.Labels{"foo": "bar", "xyz1234": "abc567"},
 				Annotations: map[string]string{"foo.io/bar": "{'key': 'val1232'}"},
 				Pod: &tsapi.Pod{
-					Labels:      map[string]string{"foo": "bar", "xyz1234": "abc567"},
+					Labels:      tsapi.Labels{"foo": "bar", "xyz1234": "abc567"},
 					Annotations: map[string]string{"foo.io/bar": "{'key': 'val1232'}"},
 					TailscaleContainer: &tsapi.Container{
 						Env:             []tsapi.Env{{Name: "FOO", Value: "BAR"}},
@@ -155,6 +155,25 @@ func TestProxyClass(t *testing.T) {
 	expectReconciled(t, pcr, "", "test")
 	tsoperator.SetProxyClassCondition(pc, tsapi.ProxyClassReady, metav1.ConditionTrue, reasonProxyClassValid, reasonProxyClassValid, 0, cl, zl.Sugar())
 	expectEqual(t, fc, pc, nil)
+
+	// 7. A ProxyClass with invalid ServiceMonitor labels gets its status updated to Invalid with an error message.
+	pc.Spec.Metrics.ServiceMonitor.Labels = tsapi.Labels{"foo": "bar!"}
+	mustUpdate(t, fc, "", "test", func(proxyClass *tsapi.ProxyClass) {
+		proxyClass.Spec.Metrics.ServiceMonitor.Labels = pc.Spec.Metrics.ServiceMonitor.Labels
+	})
+	expectReconciled(t, pcr, "", "test")
+	msg = `ProxyClass is not valid: .spec.metrics.serviceMonitor.labels: Invalid value: "bar!": a valid label must be an empty string or consist of alphanumeric characters, '-', '_' or '.', and must start and end with an alphanumeric character (e.g. 'MyValue',  or 'my_value',  or '12345', regex used for validation is '(([A-Za-z0-9][-A-Za-z0-9_.]*)?[A-Za-z0-9])?')`
+	tsoperator.SetProxyClassCondition(pc, tsapi.ProxyClassReady, metav1.ConditionFalse, reasonProxyClassInvalid, msg, 0, cl, zl.Sugar())
+	expectEqual(t, fc, pc, nil)
+
+	// 8. A ProxyClass with valid ServiceMonitor labels gets its status updated to Valid.
+	pc.Spec.Metrics.ServiceMonitor.Labels = tsapi.Labels{"foo": "bar", "xyz1234": "abc567", "empty": "", "onechar": "a"}
+	mustUpdate(t, fc, "", "test", func(proxyClass *tsapi.ProxyClass) {
+		proxyClass.Spec.Metrics.ServiceMonitor.Labels = pc.Spec.Metrics.ServiceMonitor.Labels
+	})
+	expectReconciled(t, pcr, "", "test")
+	tsoperator.SetProxyClassCondition(pc, tsapi.ProxyClassReady, metav1.ConditionTrue, reasonProxyClassValid, reasonProxyClassValid, 0, cl, zl.Sugar())
+	expectEqual(t, fc, pc, nil)
 }
 
 func TestValidateProxyClass(t *testing.T) {

cmd/k8s-operator/proxygroup_test.go

@@ -88,6 +88,7 @@ func TestProxyGroup(t *testing.T) {
 		stsName:            pg.Name,
 		parentType:         "proxygroup",
 		tailscaleNamespace: "tailscale",
+		resourceVersion:    "1",
 	}
 
 	t.Run("proxyclass_not_ready", func(t *testing.T) {

cmd/k8s-operator/sts.go

@@ -761,7 +761,7 @@ func applyProxyClassToStatefulSet(pc *tsapi.ProxyClass, ss *appsv1.StatefulSet,
 	}
 
 	// Update StatefulSet metadata.
-	if wantsSSLabels := pc.Spec.StatefulSet.Labels; len(wantsSSLabels) > 0 {
+	if wantsSSLabels := pc.Spec.StatefulSet.Labels.Parse(); len(wantsSSLabels) > 0 {
 		ss.ObjectMeta.Labels = mergeStatefulSetLabelsOrAnnots(ss.ObjectMeta.Labels, wantsSSLabels, tailscaleManagedLabels)
 	}
 	if wantsSSAnnots := pc.Spec.StatefulSet.Annotations; len(wantsSSAnnots) > 0 {
@@ -773,7 +773,7 @@ func applyProxyClassToStatefulSet(pc *tsapi.ProxyClass, ss *appsv1.StatefulSet,
 		return ss
 	}
 	wantsPod := pc.Spec.StatefulSet.Pod
-	if wantsPodLabels := wantsPod.Labels; len(wantsPodLabels) > 0 {
+	if wantsPodLabels := wantsPod.Labels.Parse(); len(wantsPodLabels) > 0 {
 		ss.Spec.Template.ObjectMeta.Labels = mergeStatefulSetLabelsOrAnnots(ss.Spec.Template.ObjectMeta.Labels, wantsPodLabels, tailscaleManagedLabels)
 	}
 	if wantsPodAnnots := wantsPod.Annotations; len(wantsPodAnnots) > 0 {

cmd/k8s-operator/sts_test.go

@@ -61,10 +61,10 @@ func Test_applyProxyClassToStatefulSet(t *testing.T) {
 	proxyClassAllOpts := &tsapi.ProxyClass{
 		Spec: tsapi.ProxyClassSpec{
 			StatefulSet: &tsapi.StatefulSet{
-				Labels:      map[string]string{"foo": "bar"},
+				Labels:      tsapi.Labels{"foo": "bar"},
 				Annotations: map[string]string{"foo.io/bar": "foo"},
 				Pod: &tsapi.Pod{
-					Labels:      map[string]string{"bar": "foo"},
+					Labels:      tsapi.Labels{"bar": "foo"},
 					Annotations: map[string]string{"bar.io/foo": "foo"},
 					SecurityContext: &corev1.PodSecurityContext{
 						RunAsUser: ptr.To(int64(0)),
@@ -116,10 +116,10 @@ func Test_applyProxyClassToStatefulSet(t *testing.T) {
 	proxyClassJustLabels := &tsapi.ProxyClass{
 		Spec: tsapi.ProxyClassSpec{
 			StatefulSet: &tsapi.StatefulSet{
-				Labels:      map[string]string{"foo": "bar"},
+				Labels:      tsapi.Labels{"foo": "bar"},
 				Annotations: map[string]string{"foo.io/bar": "foo"},
 				Pod: &tsapi.Pod{
-					Labels:      map[string]string{"bar": "foo"},
+					Labels:      tsapi.Labels{"bar": "foo"},
 					Annotations: map[string]string{"bar.io/foo": "foo"},
 				},
 			},
@@ -146,7 +146,6 @@ func Test_applyProxyClassToStatefulSet(t *testing.T) {
 			},
 		}
 	}
-
 	var userspaceProxySS, nonUserspaceProxySS appsv1.StatefulSet
 	if err := yaml.Unmarshal(userspaceProxyYaml, &userspaceProxySS); err != nil {
 		t.Fatalf("unmarshaling userspace proxy template: %v", err)
@@ -176,9 +175,9 @@ func Test_applyProxyClassToStatefulSet(t *testing.T) {
 	// 1. Test that a ProxyClass with all fields set gets correctly applied
 	// to a Statefulset built from non-userspace proxy template.
 	wantSS := nonUserspaceProxySS.DeepCopy()
-	wantSS.ObjectMeta.Labels = mergeMapKeys(wantSS.ObjectMeta.Labels, proxyClassAllOpts.Spec.StatefulSet.Labels)
-	wantSS.ObjectMeta.Annotations = mergeMapKeys(wantSS.ObjectMeta.Annotations, proxyClassAllOpts.Spec.StatefulSet.Annotations)
-	wantSS.Spec.Template.Labels = proxyClassAllOpts.Spec.StatefulSet.Pod.Labels
+	updateMap(wantSS.ObjectMeta.Labels, proxyClassAllOpts.Spec.StatefulSet.Labels.Parse())
+	updateMap(wantSS.ObjectMeta.Annotations, proxyClassAllOpts.Spec.StatefulSet.Annotations)
+	wantSS.Spec.Template.Labels = proxyClassAllOpts.Spec.StatefulSet.Pod.Labels.Parse()
 	wantSS.Spec.Template.Annotations = proxyClassAllOpts.Spec.StatefulSet.Pod.Annotations
 	wantSS.Spec.Template.Spec.SecurityContext = proxyClassAllOpts.Spec.StatefulSet.Pod.SecurityContext
 	wantSS.Spec.Template.Spec.ImagePullSecrets = proxyClassAllOpts.Spec.StatefulSet.Pod.ImagePullSecrets
@@ -207,9 +206,9 @@ func Test_applyProxyClassToStatefulSet(t *testing.T) {
 	// StatefulSet and Pod set gets correctly applied to a Statefulset built
 	// from non-userspace proxy template.
 	wantSS = nonUserspaceProxySS.DeepCopy()
-	wantSS.ObjectMeta.Labels = mergeMapKeys(wantSS.ObjectMeta.Labels, proxyClassJustLabels.Spec.StatefulSet.Labels)
-	wantSS.ObjectMeta.Annotations = mergeMapKeys(wantSS.ObjectMeta.Annotations, proxyClassJustLabels.Spec.StatefulSet.Annotations)
-	wantSS.Spec.Template.Labels = proxyClassJustLabels.Spec.StatefulSet.Pod.Labels
+	updateMap(wantSS.ObjectMeta.Labels, proxyClassJustLabels.Spec.StatefulSet.Labels.Parse())
+	updateMap(wantSS.ObjectMeta.Annotations, proxyClassJustLabels.Spec.StatefulSet.Annotations)
+	wantSS.Spec.Template.Labels = proxyClassJustLabels.Spec.StatefulSet.Pod.Labels.Parse()
 	wantSS.Spec.Template.Annotations = proxyClassJustLabels.Spec.StatefulSet.Pod.Annotations
 	gotSS = applyProxyClassToStatefulSet(proxyClassJustLabels, nonUserspaceProxySS.DeepCopy(), new(tailscaleSTSConfig), zl.Sugar())
 	if diff := cmp.Diff(gotSS, wantSS); diff != "" {
@@ -219,9 +218,9 @@ func Test_applyProxyClassToStatefulSet(t *testing.T) {
 	// 3. Test that a ProxyClass with all fields set gets correctly applied
 	// to a Statefulset built from a userspace proxy template.
 	wantSS = userspaceProxySS.DeepCopy()
-	wantSS.ObjectMeta.Labels = mergeMapKeys(wantSS.ObjectMeta.Labels, proxyClassAllOpts.Spec.StatefulSet.Labels)
-	wantSS.ObjectMeta.Annotations = mergeMapKeys(wantSS.ObjectMeta.Annotations, proxyClassAllOpts.Spec.StatefulSet.Annotations)
-	wantSS.Spec.Template.Labels = proxyClassAllOpts.Spec.StatefulSet.Pod.Labels
+	updateMap(wantSS.ObjectMeta.Labels, proxyClassAllOpts.Spec.StatefulSet.Labels.Parse())
+	updateMap(wantSS.ObjectMeta.Annotations, proxyClassAllOpts.Spec.StatefulSet.Annotations)
+	wantSS.Spec.Template.Labels = proxyClassAllOpts.Spec.StatefulSet.Pod.Labels.Parse()
 	wantSS.Spec.Template.Annotations = proxyClassAllOpts.Spec.StatefulSet.Pod.Annotations
 	wantSS.Spec.Template.Spec.SecurityContext = proxyClassAllOpts.Spec.StatefulSet.Pod.SecurityContext
 	wantSS.Spec.Template.Spec.ImagePullSecrets = proxyClassAllOpts.Spec.StatefulSet.Pod.ImagePullSecrets
@@ -243,9 +242,9 @@ func Test_applyProxyClassToStatefulSet(t *testing.T) {
 	// 4. Test that a ProxyClass with custom labels and annotations gets correctly applied
 	// to a Statefulset built from a userspace proxy template.
 	wantSS = userspaceProxySS.DeepCopy()
-	wantSS.ObjectMeta.Labels = mergeMapKeys(wantSS.ObjectMeta.Labels, proxyClassJustLabels.Spec.StatefulSet.Labels)
-	wantSS.ObjectMeta.Annotations = mergeMapKeys(wantSS.ObjectMeta.Annotations, proxyClassJustLabels.Spec.StatefulSet.Annotations)
-	wantSS.Spec.Template.Labels = proxyClassJustLabels.Spec.StatefulSet.Pod.Labels
+	updateMap(wantSS.ObjectMeta.Labels, proxyClassJustLabels.Spec.StatefulSet.Labels.Parse())
+	updateMap(wantSS.ObjectMeta.Annotations, proxyClassJustLabels.Spec.StatefulSet.Annotations)
+	wantSS.Spec.Template.Labels = proxyClassJustLabels.Spec.StatefulSet.Pod.Labels.Parse()
 	wantSS.Spec.Template.Annotations = proxyClassJustLabels.Spec.StatefulSet.Pod.Annotations
 	gotSS = applyProxyClassToStatefulSet(proxyClassJustLabels, userspaceProxySS.DeepCopy(), new(tailscaleSTSConfig), zl.Sugar())
 	if diff := cmp.Diff(gotSS, wantSS); diff != "" {
@@ -294,13 +293,6 @@ func Test_applyProxyClassToStatefulSet(t *testing.T) {
 	}
 }
 
-func mergeMapKeys(a, b map[string]string) map[string]string {
-	for key, val := range b {
-		a[key] = val
-	}
-	return a
-}
-
 func Test_mergeStatefulSetLabelsOrAnnots(t *testing.T) {
 	tests := []struct {
 		name    string
@@ -392,3 +384,10 @@ func Test_mergeStatefulSetLabelsOrAnnots(t *testing.T) {
 		})
 	}
 }
+
+// updateMap updates map a with the values from map b.
+func updateMap(a, b map[string]string) {
+	for key, val := range b {
+		a[key] = val
+	}
+}

cmd/k8s-operator/testutils_test.go

@@ -61,7 +61,10 @@ type configOpts struct {
 	app                                            string
 	shouldRemoveAuthKey                            bool
 	secretExtraData                                map[string][]byte
-	enableMetrics                                  bool
+	resourceVersion                                string
+
+	enableMetrics        bool
+	serviceMonitorLabels tsapi.Labels
 }
 
 func expectedSTS(t *testing.T, cl client.Client, opts configOpts) *appsv1.StatefulSet {
@@ -431,14 +434,17 @@ func metricsLabels(opts configOpts) map[string]string {
 
 func expectedServiceMonitor(t *testing.T, opts configOpts) *unstructured.Unstructured {
 	t.Helper()
-	labels := metricsLabels(opts)
+	smLabels := metricsLabels(opts)
+	if len(opts.serviceMonitorLabels) != 0 {
+		smLabels = mergeMapKeys(smLabels, opts.serviceMonitorLabels.Parse())
+	}
 	name := metricsResourceName(opts.stsName)
 	sm := &ServiceMonitor{
 		ObjectMeta: metav1.ObjectMeta{
 			Name:            name,
 			Namespace:       opts.tailscaleNamespace,
-			Labels:          labels,
-			ResourceVersion: "1",
+			Labels:          smLabels,
+			ResourceVersion: opts.resourceVersion,
 			OwnerReferences: []metav1.OwnerReference{{APIVersion: "v1", Kind: "Service", Name: name, BlockOwnerDeletion: ptr.To(true), Controller: ptr.To(true)}},
 		},
 		TypeMeta: metav1.TypeMeta{
@@ -446,7 +452,7 @@ func expectedServiceMonitor(t *testing.T, opts configOpts) *unstructured.Unstruc
 			APIVersion: "monitoring.coreos.com/v1",
 		},
 		Spec: ServiceMonitorSpec{
-			Selector: metav1.LabelSelector{MatchLabels: labels},
+			Selector: metav1.LabelSelector{MatchLabels: metricsLabels(opts)},
 			Endpoints: []ServiceMonitorEndpoint{{
 				Port: "metrics",
 			}},
@@ -653,10 +659,11 @@ func expectEqualUnstructured(t *testing.T, client client.Client, want *unstructu
 func expectMissing[T any, O ptrObject[T]](t *testing.T, client client.Client, ns, name string) {
 	t.Helper()
 	obj := O(new(T))
-	if err := client.Get(context.Background(), types.NamespacedName{
+	err := client.Get(context.Background(), types.NamespacedName{
 		Name:      name,
 		Namespace: ns,
-	}, obj); !apierrors.IsNotFound(err) {
+	}, obj)
+	if !apierrors.IsNotFound(err) {
 		t.Fatalf("%s %s/%s unexpectedly present, wanted missing", reflect.TypeOf(obj).Elem().Name(), ns, name)
 	}
 }

k8s-operator/api.md

@@ -313,6 +313,37 @@ _Appears in:_
 
 
 
+#### LabelValue
+
+_Underlying type:_ _string_
+
+
+
+_Validation:_
+- MaxLength: 63
+- Pattern: `^(([a-zA-Z0-9][-._a-zA-Z0-9]*)?[a-zA-Z0-9])?$`
+- Type: string
+
+_Appears in:_
+- [Labels](#labels)
+
+
+
+#### Labels
+
+_Underlying type:_ _[map[string]LabelValue](#map[string]labelvalue)_
+
+
+
+
+
+_Appears in:_
+- [Pod](#pod)
+- [ServiceMonitor](#servicemonitor)
+- [StatefulSet](#statefulset)
+
+
+
 #### Metrics
 
 
@@ -407,7 +438,7 @@ _Appears in:_
 
 | Field | Description | Default | Validation |
 | --- | --- | --- | --- |
-| `labels` _object (keys:string, values:string)_ | Labels that will be added to the proxy Pod.<br />Any labels specified here will be merged with the default labels<br />applied to the Pod by the Tailscale Kubernetes operator.<br />Label keys and values must be valid Kubernetes label keys and values.<br />https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#syntax-and-character-set |  |  |
+| `labels` _[Labels](#labels)_ | Labels that will be added to the proxy Pod.<br />Any labels specified here will be merged with the default labels<br />applied to the Pod by the Tailscale Kubernetes operator.<br />Label keys and values must be valid Kubernetes label keys and values.<br />https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#syntax-and-character-set |  |  |
 | `annotations` _object (keys:string, values:string)_ | Annotations that will be added to the proxy Pod.<br />Any annotations specified here will be merged with the default<br />annotations applied to the Pod by the Tailscale Kubernetes operator.<br />Annotations must be valid Kubernetes annotations.<br />https://kubernetes.io/docs/concepts/overview/working-with-objects/annotations/#syntax-and-character-set |  |  |
 | `affinity` _[Affinity](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.3/#affinity-v1-core)_ | Proxy Pod's affinity rules.<br />By default, the Tailscale Kubernetes operator does not apply any affinity rules.<br />https://kubernetes.io/docs/reference/kubernetes-api/workload-resources/pod-v1/#affinity |  |  |
 | `tailscaleContainer` _[Container](#container)_ | Configuration for the proxy container running tailscale. |  |  |
@@ -864,6 +895,7 @@ _Appears in:_
 | Field | Description | Default | Validation |
 | --- | --- | --- | --- |
 | `enable` _boolean_ | If Enable is set to true, a Prometheus ServiceMonitor will be created. Enable can only be set to true if metrics are enabled. |  |  |
+| `labels` _[Labels](#labels)_ | Labels to add to the ServiceMonitor.<br />Labels must be valid Kubernetes labels.<br />https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#syntax-and-character-set |  |  |
 
 
 #### StatefulSet
@@ -879,7 +911,7 @@ _Appears in:_
 
 | Field | Description | Default | Validation |
 | --- | --- | --- | --- |
-| `labels` _object (keys:string, values:string)_ | Labels that will be added to the StatefulSet created for the proxy.<br />Any labels specified here will be merged with the default labels<br />applied to the StatefulSet by the Tailscale Kubernetes operator as<br />well as any other labels that might have been applied by other<br />actors.<br />Label keys and values must be valid Kubernetes label keys and values.<br />https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#syntax-and-character-set |  |  |
+| `labels` _[Labels](#labels)_ | Labels that will be added to the StatefulSet created for the proxy.<br />Any labels specified here will be merged with the default labels<br />applied to the StatefulSet by the Tailscale Kubernetes operator as<br />well as any other labels that might have been applied by other<br />actors.<br />Label keys and values must be valid Kubernetes label keys and values.<br />https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#syntax-and-character-set |  |  |
 | `annotations` _object (keys:string, values:string)_ | Annotations that will be added to the StatefulSet created for the proxy.<br />Any Annotations specified here will be merged with the default annotations<br />applied to the StatefulSet by the Tailscale Kubernetes operator as<br />well as any other annotations that might have been applied by other<br />actors.<br />Annotations must be valid Kubernetes annotations.<br />https://kubernetes.io/docs/concepts/overview/working-with-objects/annotations/#syntax-and-character-set |  |  |
 | `pod` _[Pod](#pod)_ | Configuration for the proxy Pod. |  |  |
 

k8s-operator/apis/v1alpha1/types_proxyclass.go

@@ -87,7 +87,7 @@ type StatefulSet struct {
 	// Label keys and values must be valid Kubernetes label keys and values.
 	// https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#syntax-and-character-set
 	// +optional
-	Labels map[string]string `json:"labels,omitempty"`
+	Labels Labels `json:"labels,omitempty"`
 	// Annotations that will be added to the StatefulSet created for the proxy.
 	// Any Annotations specified here will be merged with the default annotations
 	// applied to the StatefulSet by the Tailscale Kubernetes operator as
@@ -109,7 +109,7 @@ type Pod struct {
 	// Label keys and values must be valid Kubernetes label keys and values.
 	// https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#syntax-and-character-set
 	// +optional
-	Labels map[string]string `json:"labels,omitempty"`
+	Labels Labels `json:"labels,omitempty"`
 	// Annotations that will be added to the proxy Pod.
 	// Any annotations specified here will be merged with the default
 	// annotations applied to the Pod by the Tailscale Kubernetes operator.
@@ -188,8 +188,34 @@ type Metrics struct {
 type ServiceMonitor struct {
 	// If Enable is set to true, a Prometheus ServiceMonitor will be created. Enable can only be set to true if metrics are enabled.
 	Enable bool `json:"enable"`
+	// Labels to add to the ServiceMonitor.
+	// Labels must be valid Kubernetes labels.
+	// https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#syntax-and-character-set
+	// +optional
+	Labels Labels `json:"labels"`
+}
+
+type Labels map[string]LabelValue
+
+func (l Labels) Parse() map[string]string {
+	if l == nil {
+		return nil
+	}
+	m := make(map[string]string, len(l))
+	for k, v := range l {
+		m[k] = string(v)
+	}
+	return m
 }
 
+// We do not validate the values of the label keys here - it is done by the ProxyClass
+// reconciler because the validation rules are too complex for a CRD validation markers regex.
+
+// +kubebuilder:validation:Type=string
+// +kubebuilder:validation:Pattern=`^(([a-zA-Z0-9][-._a-zA-Z0-9]*)?[a-zA-Z0-9])?$`
+// +kubebuilder:validation:MaxLength=63
+type LabelValue string
+
 type Container struct {
 	// List of environment variables to set in the container.
 	// https://kubernetes.io/docs/reference/kubernetes-api/workload-resources/pod-v1/#environment-variables

k8s-operator/apis/v1alpha1/zz_generated.deepcopy.go

@@ -316,13 +316,34 @@ func (in *Env) DeepCopy() *Env {
 	return out
 }
 
+// DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
+func (in Labels) DeepCopyInto(out *Labels) {
+	{
+		in := &in
+		*out = make(Labels, len(*in))
+		for key, val := range *in {
+			(*out)[key] = val
+		}
+	}
+}
+
+// DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new Labels.
+func (in Labels) DeepCopy() Labels {
+	if in == nil {
+		return nil
+	}
+	out := new(Labels)
+	in.DeepCopyInto(out)
+	return *out
+}
+
 // DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
 func (in *Metrics) DeepCopyInto(out *Metrics) {
 	*out = *in
 	if in.ServiceMonitor != nil {
 		in, out := &in.ServiceMonitor, &out.ServiceMonitor
 		*out = new(ServiceMonitor)
-		**out = **in
+		(*in).DeepCopyInto(*out)
 	}
 }
 
@@ -391,7 +412,7 @@ func (in *Pod) DeepCopyInto(out *Pod) {
 	*out = *in
 	if in.Labels != nil {
 		in, out := &in.Labels, &out.Labels
-		*out = make(map[string]string, len(*in))
+		*out = make(Labels, len(*in))
 		for key, val := range *in {
 			(*out)[key] = val
 		}
@@ -999,6 +1020,13 @@ func (in *S3Secret) DeepCopy() *S3Secret {
 // DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
 func (in *ServiceMonitor) DeepCopyInto(out *ServiceMonitor) {
 	*out = *in
+	if in.Labels != nil {
+		in, out := &in.Labels, &out.Labels
+		*out = make(Labels, len(*in))
+		for key, val := range *in {
+			(*out)[key] = val
+		}
+	}
 }
 
 // DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new ServiceMonitor.
@@ -1016,7 +1044,7 @@ func (in *StatefulSet) DeepCopyInto(out *StatefulSet) {
 	*out = *in
 	if in.Labels != nil {
 		in, out := &in.Labels, &out.Labels
-		*out = make(map[string]string, len(*in))
+		*out = make(Labels, len(*in))
 		for key, val := range *in {
 			(*out)[key] = val
 		}