feat: add mutating webhook to label managed deploys created by aksService

Author: jwtty

pkg/utils/common.go

@@ -60,6 +60,13 @@ const (
 	MutatingPathFmt            = "/mutate-%s-%s-%s"
 	lessGroupsStringFormat     = "groups: %v"
 	moreGroupsStringFormat     = "groups: [%s, %s, %s,......]"
+
+	// ReconcileLabelKey is the label key added to resources that should be reconciled.
+	// The value indicates the reason the resource should be reconciled.
+	ReconcileLabelKey = "fleet.azure.com/reconcile"
+	// ReconcileLabelValue is the label value paired with ReconcileLabelKey,
+	// indicating the resource is managed and should be reconciled.
+	ReconcileLabelValue = "managed"
 )
 
 const (
@@ -504,6 +511,12 @@ func IsReservedNamespace(namespace string) bool {
 	return strings.HasPrefix(namespace, fleetPrefix) || strings.HasPrefix(namespace, kubePrefix)
 }
 
+// HasReconcileLabel reports whether the given labels contain the fleet reconcile
+// label key with a non-empty value.
+func HasReconcileLabel(labels map[string]string) bool {
+	return labels[ReconcileLabelKey] != ""
+}
+
 // IsFleetMemberNamespace indicates if an argued namespace is a fleet member namespace.
 func IsFleetMemberNamespace(namespace string) bool {
 	return strings.HasPrefix(namespace, fleetMemberNamespacePrefix)

pkg/webhook/add_handler.go

@@ -5,6 +5,7 @@ import (
 	"go.goms.io/fleet/pkg/webhook/clusterresourceplacement"
 	"go.goms.io/fleet/pkg/webhook/clusterresourceplacementdisruptionbudget"
 	"go.goms.io/fleet/pkg/webhook/clusterresourceplacementeviction"
+	"go.goms.io/fleet/pkg/webhook/deployment"
 	"go.goms.io/fleet/pkg/webhook/fleetresourcehandler"
 	"go.goms.io/fleet/pkg/webhook/membercluster"
 	"go.goms.io/fleet/pkg/webhook/pdb"
@@ -29,4 +30,6 @@ func init() {
 	AddToManagerFuncs = append(AddToManagerFuncs, resourceoverride.Add)
 	AddToManagerFuncs = append(AddToManagerFuncs, clusterresourceplacementeviction.Add)
 	AddToManagerFuncs = append(AddToManagerFuncs, clusterresourceplacementdisruptionbudget.Add)
+	AddToManagerFuncs = append(AddToManagerFuncs, deployment.AddMutating)
+	AddToManagerFuncs = append(AddToManagerFuncs, deployment.Add)
 }

pkg/webhook/deployment/deployment_mutating_webhook.go

@@ -0,0 +1,90 @@
+/*
+Copyright 2025 The KubeFleet Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package deployment
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+
+	appsv1 "k8s.io/api/apps/v1"
+	"k8s.io/klog/v2"
+	"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"
+)
+
+// MutatingPath is the webhook service path for mutating Deployment resources.
+var MutatingPath = fmt.Sprintf(utils.MutatingPathFmt, appsv1.SchemeGroupVersion.Group, appsv1.SchemeGroupVersion.Version, "deployment")
+
+type deploymentMutator struct {
+	decoder webhook.AdmissionDecoder
+}
+
+// AddMutating registers the mutating webhook for Deployments with the manager.
+func AddMutating(mgr manager.Manager) error {
+	hookServer := mgr.GetWebhookServer()
+	hookServer.Register(MutatingPath, &webhook.Admission{Handler: &deploymentMutator{decoder: admission.NewDecoder(mgr.GetScheme())}})
+	return nil
+}
+
+// Handle injects the fleet.azure.com/reconcile=managed label onto the
+// Deployment and its pod template when the request originated from the aksService user.
+func (m *deploymentMutator) Handle(_ context.Context, req admission.Request) admission.Response {
+	klog.V(2).InfoS("handling deployment mutating webhook",
+		"operation", req.Operation, "namespace", req.Namespace, "name", req.Name, "user", req.UserInfo.Username)
+
+	// Pass through requests targeting reserved system namespaces.
+	if utils.IsReservedNamespace(req.Namespace) {
+		return admission.Allowed(fmt.Sprintf("namespace %s is a reserved system namespace, no mutation needed", req.Namespace))
+	}
+
+	// Only mutate when the request was made by the aksService user with
+	// system:masters group membership.
+	if !isAKSService(req.UserInfo) {
+		return admission.Allowed("user is not aksService, no mutation needed")
+	}
+
+	var deploy appsv1.Deployment
+	if err := m.decoder.Decode(req, &deploy); err != nil {
+		return admission.Errored(http.StatusBadRequest, err)
+	}
+
+	// Add the reconcile label on the Deployment metadata.
+	if deploy.Labels == nil {
+		deploy.Labels = map[string]string{}
+	}
+	deploy.Labels[utils.ReconcileLabelKey] = utils.ReconcileLabelValue
+
+	// Add the reconcile label on the pod template metadata.
+	if deploy.Spec.Template.Labels == nil {
+		deploy.Spec.Template.Labels = map[string]string{}
+	}
+	deploy.Spec.Template.Labels[utils.ReconcileLabelKey] = utils.ReconcileLabelValue
+
+	marshaled, err := json.Marshal(deploy)
+	if err != nil {
+		return admission.Errored(http.StatusInternalServerError, err)
+	}
+
+	klog.V(2).InfoS("mutated deployment with reconcile label",
+		"operation", req.Operation, "namespace", req.Namespace, "name", req.Name)
+	return admission.PatchResponseFromRaw(req.Object.Raw, marshaled)
+}