Implementation + Tests

pkg/predicate/predicate.go

@@ -17,6 +17,8 @@ limitations under the License.
 package predicate
 
 import (
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/labels"
 	"sigs.k8s.io/controller-runtime/pkg/controller/controllerutil"
 	"sigs.k8s.io/controller-runtime/pkg/event"
 	logf "sigs.k8s.io/controller-runtime/pkg/internal/log"
@@ -268,3 +270,16 @@ func (o or) Generic(e event.GenericEvent) bool {
 	}
 	return false
 }
+
+// LabelSelectorPredicate takes in a LabelSelector as a parameter and returns predicate functions. The labels of
+// events that are contained as parameters in these predicate functions are compared against the instantiated
+// Selector object and reconciliation of the event will only take place if the labels match.
+func LabelSelectorPredicate(s metav1.LabelSelector) (Funcs, error) {
+	selector, err := metav1.LabelSelectorAsSelector(&s)
+	if err != nil {
+		return Funcs{}, err
+	}
+	return NewPredicateFuncs(func(o controllerutil.Object) bool {
+		return selector.Matches(labels.Set(o.GetLabels()))
+	}), nil
+}

pkg/predicate/predicate_test.go

@@ -516,4 +516,39 @@ var _ = Describe("Predicate", func() {
 			})
 		})
 	})
+
+	Describe("When checking a LabelSelectorPredicate", func() {
+		instance, err := predicate.LabelSelectorPredicate(*(&metav1.LabelSelector{MatchLabels: map[string]string{"foo": "bar"}}))
+		if err != nil {
+			Fail("Improper Label Selector passed during predicate instantiation.")
+		}
+
+		Context("When the Selector does not match the event labels", func() {
+			It("should return false", func() {
+				failMatch := &corev1.Pod{
+					ObjectMeta: metav1.ObjectMeta{
+						Labels: map[string]string{"bar": "foo"},
+					},
+				}
+				Expect(instance.Create(event.CreateEvent{Object: failMatch})).To(BeFalse())
+				Expect(instance.Delete(event.DeleteEvent{Object: failMatch})).To(BeFalse())
+				Expect(instance.Generic(event.GenericEvent{Object: failMatch})).To(BeFalse())
+				Expect(instance.Update(event.UpdateEvent{ObjectNew: failMatch})).To(BeFalse())
+			})
+		})
+
+		Context("When the Selector matches the event labels", func() {
+			It("should return true", func() {
+				successMatch := &corev1.Pod{
+					ObjectMeta: metav1.ObjectMeta{
+						Labels: map[string]string{"foo": "bar"},
+					},
+				}
+				Expect(instance.Create(event.CreateEvent{Object: successMatch})).To(BeTrue())
+				Expect(instance.Delete(event.DeleteEvent{Object: successMatch})).To(BeTrue())
+				Expect(instance.Generic(event.GenericEvent{Object: successMatch})).To(BeTrue())
+				Expect(instance.Update(event.UpdateEvent{ObjectNew: successMatch})).To(BeTrue())
+			})
+		})
+	})
 })