feat: ReplicaSet validation webhook

pkg/utils/common.go

@@ -242,10 +242,14 @@ func ShouldPropagateObj(informerManager informer.Manager, uObj *unstructured.Uns
 	return true, nil
 }
 
-// ShouldPropagateNamespace decides if we should propagate the resources in the namespace
+// IsReservedNamespace indicates if an argued namespace is reserved.
+func IsReservedNamespace(namespace string) bool {
+	return strings.HasPrefix(namespace, fleetPrefix) || strings.HasPrefix(namespace, kubePrefix)
+}
+
+// ShouldPropagateNamespace decides if we should propagate the resources in the namespace.
 func ShouldPropagateNamespace(namespace string, skippedNamespaces map[string]bool) bool {
-	// special case for namespace have the reserved prefix
-	if strings.HasPrefix(namespace, fleetPrefix) || strings.HasPrefix(namespace, kubePrefix) {
+	if IsReservedNamespace(namespace) {
 		return false
 	}
 

pkg/webhook/add_replicaset.go

@@ -0,0 +1,14 @@
+/*
+Copyright (c) Microsoft Corporation.
+Licensed under the MIT license.
+*/
+
+package webhook
+
+import (
+	"go.goms.io/fleet/pkg/webhook/replicaset"
+)
+
+func init() {
+	AddToManagerFuncs = append(AddToManagerFuncs, replicaset.Add)
+}

pkg/webhook/pod/pod_validating_webhook.go

@@ -16,6 +16,8 @@ import (
 	"sigs.k8s.io/controller-runtime/pkg/manager"
 	"sigs.k8s.io/controller-runtime/pkg/webhook"
 	"sigs.k8s.io/controller-runtime/pkg/webhook/admission"
+
+	"go.goms.io/fleet/pkg/utils"
 )
 
 const (
@@ -43,7 +45,7 @@ func (v *podValidator) Handle(ctx context.Context, req admission.Request) admiss
 		if err != nil {
 			return admission.Errored(http.StatusBadRequest, err)
 		}
-		if pod.Namespace != "kube-system" && pod.Namespace != "fleet-system" {
+		if !utils.IsReservedNamespace(pod.Namespace) {
 			return admission.Denied(fmt.Sprintf("Pod %s/%s creation is disallowed in the fleet hub cluster", pod.Namespace, pod.Name))
 		}
 	}

pkg/webhook/replicaset/replicaset_validating_webhook.go

@@ -0,0 +1,58 @@
+/*
+Copyright (c) Microsoft Corporation.
+Licensed under the MIT license.
+*/
+
+package replicaset
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+
+	admissionv1 "k8s.io/api/admission/v1"
+	v1 "k8s.io/api/apps/v1"
+	"sigs.k8s.io/controller-runtime/pkg/client"
+	"sigs.k8s.io/controller-runtime/pkg/manager"
+	"sigs.k8s.io/controller-runtime/pkg/webhook"
+	"sigs.k8s.io/controller-runtime/pkg/webhook/admission"
+
+	"go.goms.io/fleet/pkg/utils"
+)
+
+const (
+	// ValidationPath is the webhook service path which admission requests are routed to for validating ReplicaSet resources.
+	ValidationPath = "/validate-apps-v1-replicaset"
+)
+
+type replicaSetValidator struct {
+	Client  client.Client
+	decoder *admission.Decoder
+}
+
+// Add registers the webhook for K8s bulit-in object types.
+func Add(mgr manager.Manager) error {
+	hookServer := mgr.GetWebhookServer()
+	hookServer.Register(ValidationPath, &webhook.Admission{Handler: &replicaSetValidator{Client: mgr.GetClient()}})
+	return nil
+}
+
+// Handle replicaSetValidator denies all creation requests.
+func (v *replicaSetValidator) Handle(ctx context.Context, req admission.Request) admission.Response {
+	if req.Operation == admissionv1.Create {
+		rs := &v1.ReplicaSet{}
+		if err := v.decoder.Decode(req, rs); err != nil {
+			return admission.Errored(http.StatusBadRequest, err)
+		}
+		if !utils.IsReservedNamespace(rs.Namespace) {
+			return admission.Denied(fmt.Sprintf("ReplicaSet %s/%s creation is disallowed in the fleet hub cluster.", rs.Namespace, rs.Name))
+		}
+	}
+	return admission.Allowed("")
+}
+
+// InjectDecoder injects the decoder.
+func (v *replicaSetValidator) InjectDecoder(d *admission.Decoder) error {
+	v.decoder = d
+	return nil
+}

pkg/webhook/webhook.go

@@ -21,6 +21,7 @@ import (
 	"time"
 
 	admv1 "k8s.io/api/admissionregistration/v1"
+	appsv1 "k8s.io/api/apps/v1"
 	corev1 "k8s.io/api/core/v1"
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -32,6 +33,7 @@ import (
 	"go.goms.io/fleet/cmd/hubagent/options"
 	"go.goms.io/fleet/pkg/webhook/clusterresourceplacement"
 	"go.goms.io/fleet/pkg/webhook/pod"
+	"go.goms.io/fleet/pkg/webhook/replicaset"
 )
 
 const (
@@ -82,7 +84,7 @@ func NewWebhookConfig(mgr manager.Manager, port int, clientConnectionType *optio
 	}
 	caPEM, err := w.genCertificate(certDir)
 	if err != nil {
-		return nil, err // TODO
+		return nil, err
 	}
 	w.caPEM = caPEM
 	return &w, err
@@ -97,9 +99,9 @@ func (w *Config) Start(ctx context.Context) error {
 	return nil
 }
 
-// createFleetWebhookConfiguration creates the ValidatingWebhookConfiguration object for the webhook
+// createFleetWebhookConfiguration creates the ValidatingWebhookConfiguration object for the webhook.
 func (w *Config) createFleetWebhookConfiguration(ctx context.Context) error {
-	failPolicy := admv1.Fail // reject request if the webhook doesn't work
+	failPolicy := admv1.Fail
 	sideEffortsNone := admv1.SideEffectClassNone
 	namespacedScope := admv1.NamespacedScope
 	clusterScope := admv1.ClusterScope
@@ -155,6 +157,26 @@ func (w *Config) createFleetWebhookConfiguration(ctx context.Context) error {
 					},
 				},
 			},
+			{
+				Name:                    "fleet.replicaset.validating",
+				ClientConfig:            w.createClientConfig(appsv1.ReplicaSet{}),
+				FailurePolicy:           &failPolicy,
+				SideEffects:             &sideEffortsNone,
+				AdmissionReviewVersions: []string{"v1", "v1beta1"},
+				Rules: []admv1.RuleWithOperations{
+					{
+						Operations: []admv1.OperationType{
+							admv1.Create,
+						},
+						Rule: admv1.Rule{
+							APIGroups:   []string{"apps"},
+							APIVersions: []string{"v1"},
+							Resources:   []string{"replicasets"},
+							Scope:       &namespacedScope,
+						},
+					},
+				},
+			},
 		},
 	}
 
@@ -178,6 +200,7 @@ func (w *Config) createFleetWebhookConfiguration(ctx context.Context) error {
 	return nil
 }
 
+// createClientConfig generates the client configuration with either service ref or URL for the argued interface.
 func (w *Config) createClientConfig(webhookInterface interface{}) admv1.WebhookClientConfig {
 	serviceRef := admv1.ServiceReference{
 		Namespace: w.serviceNamespace,
@@ -192,6 +215,9 @@ func (w *Config) createClientConfig(webhookInterface interface{}) admv1.WebhookC
 	case fleetv1alpha1.ClusterResourcePlacement:
 		serviceEndpoint = w.serviceURL + clusterresourceplacement.ValidationPath
 		serviceRef.Path = pointer.String(clusterresourceplacement.ValidationPath)
+	case appsv1.ReplicaSet:
+		serviceEndpoint = w.serviceURL + replicaset.ValidationPath
+		serviceRef.Path = pointer.String(replicaset.ValidationPath)
 	}
 
 	config := admv1.WebhookClientConfig{
@@ -206,7 +232,7 @@ func (w *Config) createClientConfig(webhookInterface interface{}) admv1.WebhookC
 	return config
 }
 
-// genCertificate generates the serving cerficiate for the webhook server
+// genCertificate generates the serving cerficiate for the webhook server.
 func (w *Config) genCertificate(certDir string) ([]byte, error) {
 	caPEM, certPEM, keyPEM, err := w.genSelfSignedCert()
 	if err != nil {

test/e2e/e2e_test.go

@@ -43,17 +43,31 @@ var (
 	imc               *v1alpha1.InternalMemberCluster
 	ctx               context.Context
 
-	// This namespace will store Member cluster-related CRs, such as v1alpha1.MemberCluster
+	// The fleet-system namespace.
+	fleetSystemNamespace = &corev1.Namespace{
+		ObjectMeta: metav1.ObjectMeta{
+			Name: "fleet-system",
+		},
+	}
+
+	// The kube-system namespace
+	kubeSystemNamespace = &corev1.Namespace{
+		ObjectMeta: metav1.ObjectMeta{
+			Name: "kube-system",
+		},
+	}
+
+	// This namespace will store Member cluster-related CRs, such as v1alpha1.MemberCluster.
 	memberNamespace = &corev1.Namespace{
 		ObjectMeta: metav1.ObjectMeta{
-			Name: fmt.Sprintf(utils.NamespaceNameFormat, MemberCluster.ClusterName),
+			Name: fmt.Sprintf("fleet-member-%s", MemberCluster.ClusterName),
 		},
 	}
 
 	// This namespace in HubCluster will store v1alpha1.Work to simulate Work-related features in Hub Cluster.
 	workNamespace = &corev1.Namespace{
 		ObjectMeta: metav1.ObjectMeta{
-			Name: fmt.Sprintf(utils.NamespaceNameFormat, MemberCluster.ClusterName),
+			Name: fmt.Sprintf("fleet-member-%s", MemberCluster.ClusterName),
 		},
 	}
 
@@ -174,7 +188,7 @@ var _ = BeforeSuite(func() {
 	identity := rbacv1.Subject{
 		Name:      "member-agent-sa",
 		Kind:      "ServiceAccount",
-		Namespace: "fleet-system",
+		Namespace: utils.FleetSystemNamespace,
 	}
 	mc = &v1alpha1.MemberCluster{
 		ObjectMeta: metav1.ObjectMeta{