feat: support the class-name as override value

apis/placement/v1alpha1/common.go

@@ -33,4 +33,7 @@ const (
 
 	// ApprovalTaskNameFmt is the format of the approval task name.
 	ApprovalTaskNameFmt = "%s-%s"
+
+	// OverrideClusterNameVariable is the reserved variable in the override value that will be replaced by the actual cluster name.
+	OverrideClusterNameVariable = "${MEMBER-CLUSTER-NAME}"
 )

apis/placement/v1alpha1/override_types.go

@@ -191,6 +191,10 @@ type JSONPatchOverride struct {
 	Path string `json:"path"`
 	// Value defines the content to be applied on the target location.
 	// Value should be empty when operator is `remove`.
+	// We have reserved a few variables in this field that will be replaced by the actual values.
+	// Those variables all start with `$` and are case sensitive.
+	// Here is the list of currently supported variables:
+	// `${MEMBER-CLUSTER-NAME}`:  this will be replaced by the name of the memberCluster CR that represents this cluster.
 	// +optional
 	Value apiextensionsv1.JSON `json:"value,omitempty"`
 }

pkg/controllers/workgenerator/controller.go

@@ -18,7 +18,7 @@ import (
 	"go.uber.org/atomic"
 	"golang.org/x/sync/errgroup"
 	corev1 "k8s.io/api/core/v1"
-	equality "k8s.io/apimachinery/pkg/api/equality"
+	"k8s.io/apimachinery/pkg/api/equality"
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/api/meta"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -145,7 +145,7 @@ func (r *Reconciler) Reconcile(ctx context.Context, req controllerruntime.Reques
 	works, syncErr := r.listAllWorksAssociated(ctx, &resourceBinding)
 	if syncErr == nil {
 		// generate and apply the workUpdated works if we have all the works
-		overrideSucceeded, workUpdated, syncErr = r.syncAllWork(ctx, &resourceBinding, works, cluster)
+		overrideSucceeded, workUpdated, syncErr = r.syncAllWork(ctx, &resourceBinding, works, &cluster)
 	}
 	// Reset the conditions and failed placements.
 	for i := condition.OverriddenCondition; i < condition.TotalCondition; i++ {
@@ -379,7 +379,7 @@ func (r *Reconciler) listAllWorksAssociated(ctx context.Context, resourceBinding
 // it returns
 // 1: if we apply the overrides successfully
 // 2: if we actually made any changes on the hub cluster
-func (r *Reconciler) syncAllWork(ctx context.Context, resourceBinding *fleetv1beta1.ClusterResourceBinding, existingWorks map[string]*fleetv1beta1.Work, cluster clusterv1beta1.MemberCluster) (bool, bool, error) {
+func (r *Reconciler) syncAllWork(ctx context.Context, resourceBinding *fleetv1beta1.ClusterResourceBinding, existingWorks map[string]*fleetv1beta1.Work, cluster *clusterv1beta1.MemberCluster) (bool, bool, error) {
 	updateAny := atomic.NewBool(false)
 	resourceBindingRef := klog.KObj(resourceBinding)
 	// the hash256 function can can handle empty list https://go.dev/play/p/_4HW17fooXM

pkg/controllers/workgenerator/override.go

@@ -9,6 +9,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"strings"
 
 	jsonpatch "github.com/evanphx/json-patch/v5"
 	"k8s.io/apimachinery/pkg/api/errors"
@@ -97,7 +98,7 @@ func (r *Reconciler) fetchResourceOverrideSnapshots(ctx context.Context, resourc
 // It returns
 //   - true if the resource is deleted by the overrides.
 //   - an error if the override rules are invalid.
-func (r *Reconciler) applyOverrides(resource *placementv1beta1.ResourceContent, cluster clusterv1beta1.MemberCluster,
+func (r *Reconciler) applyOverrides(resource *placementv1beta1.ResourceContent, cluster *clusterv1beta1.MemberCluster,
 	croMap map[placementv1beta1.ResourceIdentifier][]*placementv1alpha1.ClusterResourceOverrideSnapshot, roMap map[placementv1beta1.ResourceIdentifier][]*placementv1alpha1.ResourceOverrideSnapshot) (bool, error) {
 	if len(croMap) == 0 && len(roMap) == 0 {
 		return false, nil
@@ -168,7 +169,7 @@ func (r *Reconciler) applyOverrides(resource *placementv1beta1.ResourceContent,
 	return resource.Raw == nil, nil
 }
 
-func applyOverrideRules(resource *placementv1beta1.ResourceContent, cluster clusterv1beta1.MemberCluster, rules []placementv1alpha1.OverrideRule) error {
+func applyOverrideRules(resource *placementv1beta1.ResourceContent, cluster *clusterv1beta1.MemberCluster, rules []placementv1alpha1.OverrideRule) error {
 	for _, rule := range rules {
 		matched, err := overrider.IsClusterMatched(cluster, rule)
 		if err != nil {
@@ -184,7 +185,7 @@ func applyOverrideRules(resource *placementv1beta1.ResourceContent, cluster clus
 			return nil
 		}
 		// Apply JSONPatchOverrides by default
-		if err := applyJSONPatchOverride(resource, rule.JSONPatchOverrides); err != nil {
+		if err := applyJSONPatchOverride(resource, cluster, rule.JSONPatchOverrides); err != nil {
 			klog.ErrorS(err, "Failed to apply JSON patch override")
 			return controller.NewUserError(err)
 		}
@@ -193,10 +194,18 @@ func applyOverrideRules(resource *placementv1beta1.ResourceContent, cluster clus
 }
 
 // applyJSONPatchOverride applies a JSON patch on the selected resources following [RFC 6902](https://datatracker.ietf.org/doc/html/rfc6902).
-func applyJSONPatchOverride(resourceContent *placementv1beta1.ResourceContent, overrides []placementv1alpha1.JSONPatchOverride) error {
+func applyJSONPatchOverride(resourceContent *placementv1beta1.ResourceContent, cluster *clusterv1beta1.MemberCluster, overrides []placementv1alpha1.JSONPatchOverride) error {
 	if len(overrides) == 0 { // do nothing
 		return nil
 	}
+	// go through the JSON patch overrides to replace the built-in variables before json Marshal
+	// as it may contain the built-in variables that cannot be marshaled directly
+	for i := range overrides {
+		// find and replace a few special built-in variables
+		// replace the built-in variable with the actual cluster name
+		processedJSONStr := []byte(strings.ReplaceAll(string(overrides[i].Value.Raw), placementv1alpha1.OverrideClusterNameVariable, cluster.Name))
+		overrides[i].Value.Raw = processedJSONStr
+	}
 
 	jsonPatchBytes, err := json.Marshal(overrides)
 	if err != nil {

pkg/controllers/workgenerator/override_test.go

@@ -8,6 +8,7 @@ package workgenerator
 import (
 	"context"
 	"errors"
+	"fmt"
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
@@ -1102,7 +1103,7 @@ func TestApplyOverrides_clusterScopedResource(t *testing.T) {
 				InformerManager: &fakeInformer,
 			}
 			rc := resource.CreateResourceContentForTest(t, tc.clusterRole)
-			gotDeleted, err := r.applyOverrides(rc, tc.cluster, tc.croMap, nil)
+			gotDeleted, err := r.applyOverrides(rc, &tc.cluster, tc.croMap, nil)
 			if gotErr, wantErr := err != nil, tc.wantErr != nil; gotErr != wantErr || !errors.Is(err, tc.wantErr) {
 				t.Fatalf("applyOverrides() got error %v, want error %v", err, tc.wantErr)
 			}
@@ -1964,14 +1965,87 @@ func TestApplyOverrides_namespacedScopeResource(t *testing.T) {
 			},
 			wantDelete: true,
 		},
+		{
+			name: "cluster name as value in json patch of resourceOverride",
+			deployment: appsv1.Deployment{
+				TypeMeta: deploymentType,
+				ObjectMeta: metav1.ObjectMeta{
+					Name:      "deployment-name",
+					Namespace: "deployment-namespace",
+					Labels: map[string]string{
+						"app":  "app1",
+						"key2": "value2",
+					},
+				},
+			},
+			cluster: clusterv1beta1.MemberCluster{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "cluster-1",
+					Labels: map[string]string{
+						"app": "value1",
+					},
+				},
+			},
+			roMap: map[placementv1beta1.ResourceIdentifier][]*placementv1alpha1.ResourceOverrideSnapshot{
+				{
+					Group:     utils.DeploymentGVK.Group,
+					Version:   utils.DeploymentGVK.Version,
+					Kind:      utils.DeploymentGVK.Kind,
+					Name:      "deployment-name",
+					Namespace: "deployment-namespace",
+				}: {
+					{
+						Spec: placementv1alpha1.ResourceOverrideSnapshotSpec{
+							OverrideSpec: placementv1alpha1.ResourceOverrideSpec{
+								Policy: &placementv1alpha1.OverridePolicy{
+									OverrideRules: []placementv1alpha1.OverrideRule{
+										{
+											ClusterSelector: &placementv1beta1.ClusterSelector{}, // matching all the clusters
+											OverrideType:    placementv1alpha1.JSONPatchOverrideType,
+											JSONPatchOverrides: []placementv1alpha1.JSONPatchOverride{
+												{
+													Operator: placementv1alpha1.JSONPatchOverrideOpReplace,
+													Path:     "/metadata/labels/app",
+													Value:    apiextensionsv1.JSON{Raw: []byte(fmt.Sprintf(`"%s"`, placementv1alpha1.OverrideClusterNameVariable))},
+												},
+												{
+													Operator: placementv1alpha1.JSONPatchOverrideOpAdd,
+													Path:     "/metadata/annotations",
+													Value:    apiextensionsv1.JSON{Raw: []byte(fmt.Sprintf("{\"app\": \"%s\", \"test\": \"nginx\"}", placementv1alpha1.OverrideClusterNameVariable))},
+												},
+											},
+										},
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+			wantDeployment: appsv1.Deployment{
+				TypeMeta: deploymentType,
+				ObjectMeta: metav1.ObjectMeta{
+					Name:      "deployment-name",
+					Namespace: "deployment-namespace",
+					Labels: map[string]string{
+						"app":  "cluster-1",
+						"key2": "value2",
+					},
+					Annotations: map[string]string{
+						"app":  "cluster-1",
+						"test": "nginx",
+					},
+				},
+			},
+		},
 	}
 	for _, tc := range tests {
 		t.Run(tc.name, func(t *testing.T) {
 			r := Reconciler{
 				InformerManager: &fakeInformer,
 			}
 			rc := resource.CreateResourceContentForTest(t, tc.deployment)
-			gotDeleted, err := r.applyOverrides(rc, tc.cluster, tc.croMap, tc.roMap)
+			gotDeleted, err := r.applyOverrides(rc, &tc.cluster, tc.croMap, tc.roMap)
 			if gotErr, wantErr := err != nil, tc.wantErr != nil; gotErr != wantErr || !errors.Is(err, tc.wantErr) {
 				t.Fatalf("applyOverrides() got error %v, want error %v", err, tc.wantErr)
 			}
@@ -2012,6 +2086,7 @@ func TestApplyJSONPatchOverride(t *testing.T) {
 		name           string
 		deployment     appsv1.Deployment
 		overrides      []placementv1alpha1.JSONPatchOverride
+		cluster        *clusterv1beta1.MemberCluster
 		wantDeployment appsv1.Deployment
 		wantErr        bool
 	}{
@@ -2070,6 +2145,7 @@ func TestApplyJSONPatchOverride(t *testing.T) {
 				},
 			},
 		},
+
 		{
 			name: "remove a label",
 			deployment: appsv1.Deployment{
@@ -2208,12 +2284,105 @@ func TestApplyJSONPatchOverride(t *testing.T) {
 			},
 			wantErr: true,
 		},
+		{
+			name: "typo in template variable should just be rendered as is",
+			deployment: appsv1.Deployment{
+				TypeMeta: deploymentType,
+				ObjectMeta: metav1.ObjectMeta{
+					Name:      "deployment-name",
+					Namespace: "deployment-namespace",
+					Labels: map[string]string{
+						"app": "nginx",
+					},
+				},
+			},
+			overrides: []placementv1alpha1.JSONPatchOverride{
+				{
+					Operator: placementv1alpha1.JSONPatchOverrideOpReplace,
+					Path:     "/metadata/labels/app",
+					Value:    apiextensionsv1.JSON{Raw: []byte(`"$CLUSTER_NAME"`)},
+				},
+				{
+					Operator: placementv1alpha1.JSONPatchOverrideOpAdd,
+					Path:     "/metadata/labels/${Member-Cluster-Name}",
+					Value:    apiextensionsv1.JSON{Raw: []byte(`"${CLUSTER-NAME}"`)},
+				},
+			},
+			cluster: &clusterv1beta1.MemberCluster{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "cluster-1",
+				},
+			},
+			wantDeployment: appsv1.Deployment{
+				TypeMeta: deploymentType,
+				ObjectMeta: metav1.ObjectMeta{
+					Name:      "deployment-name",
+					Namespace: "deployment-namespace",
+					Labels: map[string]string{
+						"app":                    "$CLUSTER_NAME",
+						"${Member-Cluster-Name}": "${CLUSTER-NAME}",
+					},
+				},
+			},
+		},
+		{
+			name: "multiple rules with cluster name template",
+			deployment: appsv1.Deployment{
+				TypeMeta: deploymentType,
+				ObjectMeta: metav1.ObjectMeta{
+					Name:      "deployment-name",
+					Namespace: "deployment-namespace",
+					Labels: map[string]string{
+						"app": "nginx",
+					},
+				},
+			},
+			overrides: []placementv1alpha1.JSONPatchOverride{
+				{
+					Operator: placementv1alpha1.JSONPatchOverrideOpReplace,
+					Path:     "/metadata/labels/app",
+					Value:    apiextensionsv1.JSON{Raw: []byte(fmt.Sprintf(`"%s"`, placementv1alpha1.OverrideClusterNameVariable))},
+				},
+				{
+					Operator: placementv1alpha1.JSONPatchOverrideOpAdd,
+					Path:     "/metadata/annotations",
+					Value:    apiextensionsv1.JSON{Raw: []byte(fmt.Sprintf("{\"app\": \"workload-%s\", \"test\": \"nginx\"}", placementv1alpha1.OverrideClusterNameVariable))},
+				},
+			},
+			cluster: &clusterv1beta1.MemberCluster{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "cluster-1",
+				},
+			},
+			wantDeployment: appsv1.Deployment{
+				TypeMeta: deploymentType,
+				ObjectMeta: metav1.ObjectMeta{
+					Name:      "deployment-name",
+					Namespace: "deployment-namespace",
+					Labels: map[string]string{
+						"app": "cluster-1",
+					},
+					Annotations: map[string]string{
+						"app":  "workload-cluster-1",
+						"test": "nginx",
+					},
+				},
+			},
+		},
 	}
 
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
 			rc := resource.CreateResourceContentForTest(t, tc.deployment)
-			err := applyJSONPatchOverride(rc, tc.overrides)
+			cluster := tc.cluster
+			if cluster == nil {
+				cluster = &clusterv1beta1.MemberCluster{
+					ObjectMeta: metav1.ObjectMeta{
+						Name: "cluster-1",
+					},
+				}
+			}
+			err := applyJSONPatchOverride(rc, cluster, tc.overrides)
 			if gotErr := err != nil; gotErr != tc.wantErr {
 				t.Fatalf("applyJSONPatchOverride() = error %v, want %v", err, tc.wantErr)
 			}

pkg/utils/overrider/overrider.go

@@ -172,7 +172,7 @@ func PickFromResourceMatchedOverridesForTargetCluster(
 
 	croFiltered := make([]*placementv1alpha1.ClusterResourceOverrideSnapshot, 0, len(croList))
 	for i, cro := range croList {
-		matched, err := isClusterMatched(cluster, cro.Spec.OverrideSpec.Policy)
+		matched, err := isClusterMatched(&cluster, cro.Spec.OverrideSpec.Policy)
 		if err != nil {
 			klog.ErrorS(err, "Invalid clusterResourceOverride", "clusterResourceOverride", klog.KObj(cro))
 			return nil, nil, controller.NewUnexpectedBehaviorError(err)
@@ -188,7 +188,7 @@ func PickFromResourceMatchedOverridesForTargetCluster(
 
 	roFiltered := make([]*placementv1alpha1.ResourceOverrideSnapshot, 0, len(roList))
 	for i, ro := range roList {
-		matched, err := isClusterMatched(cluster, ro.Spec.OverrideSpec.Policy)
+		matched, err := isClusterMatched(&cluster, ro.Spec.OverrideSpec.Policy)
 		if err != nil {
 			klog.ErrorS(err, "Invalid resourceOverride", "resourceOverride", klog.KObj(ro))
 			return nil, nil, controller.NewUnexpectedBehaviorError(err)
@@ -216,7 +216,7 @@ func PickFromResourceMatchedOverridesForTargetCluster(
 	return croNames, roNames, nil
 }
 
-func isClusterMatched(cluster clusterv1beta1.MemberCluster, policy *placementv1alpha1.OverridePolicy) (bool, error) {
+func isClusterMatched(cluster *clusterv1beta1.MemberCluster, policy *placementv1alpha1.OverridePolicy) (bool, error) {
 	if policy == nil {
 		return false, errors.New("policy is nil")
 	}
@@ -233,7 +233,7 @@ func isClusterMatched(cluster clusterv1beta1.MemberCluster, policy *placementv1a
 }
 
 // IsClusterMatched checks if the cluster is matched with the override rules.
-func IsClusterMatched(cluster clusterv1beta1.MemberCluster, rule placementv1alpha1.OverrideRule) (bool, error) {
+func IsClusterMatched(cluster *clusterv1beta1.MemberCluster, rule placementv1alpha1.OverrideRule) (bool, error) {
 	if rule.ClusterSelector == nil { // it means matching no member clusters
 		return false, nil
 	}

pkg/utils/overrider/overrider_test.go

@@ -1886,7 +1886,7 @@ func TestIsClusterMatched(t *testing.T) {
 	}
 	for _, tc := range tests {
 		t.Run(tc.name, func(t *testing.T) {
-			got, err := IsClusterMatched(tc.cluster, tc.rule)
+			got, err := IsClusterMatched(&tc.cluster, tc.rule)
 			if err != nil {
 				t.Fatalf("IsClusterMatched() got error %v, want nil", err)
 			}