✨ Add ContainsLabels helper option for List calls

Signed-off-by: Vince Prignano <vincepri@vmware.com>

pkg/client/fake/client_test.go

@@ -122,8 +122,8 @@ var _ = Describe("Fake client", func() {
 			Expect(list.Items).To(HaveLen(2))
 		})
 
-		It("should support filtering by labels", func() {
-			By("Listing deployments with a particular label")
+		It("should support filtering by labels and their values", func() {
+			By("Listing deployments with a particular label and value")
 			list := &appsv1.DeploymentList{}
 			err := cl.List(nil, list, client.InNamespace("ns1"),
 				client.MatchingLabels(map[string]string{
@@ -134,6 +134,16 @@ var _ = Describe("Fake client", func() {
 			Expect(list.Items).To(ConsistOf(*dep2))
 		})
 
+		It("should support filtering by label existence", func() {
+			By("Listing deployments with a particular label")
+			list := &appsv1.DeploymentList{}
+			err := cl.List(nil, list, client.InNamespace("ns1"),
+				client.ContainsLabels{"test-label"})
+			Expect(err).To(BeNil())
+			Expect(list.Items).To(HaveLen(1))
+			Expect(list.Items).To(ConsistOf(*dep2))
+		})
+
 		It("should be able to Create", func() {
 			By("Creating a new configmap")
 			newcm := &corev1.ConfigMap{

pkg/client/options.go

@@ -20,6 +20,7 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/fields"
 	"k8s.io/apimachinery/pkg/labels"
+	"k8s.io/apimachinery/pkg/selection"
 )
 
 // {{{ "Functional" Option Interfaces
@@ -388,6 +389,25 @@ func (m MatchingLabels) ApplyToDeleteAllOf(opts *DeleteAllOfOptions) {
 	m.ApplyToList(&opts.ListOptions)
 }
 
+// ContainsLabels filters the list/delete operation checking if the set of labels exists
+// without checking their values.
+type ContainsLabels []string
+
+func (m ContainsLabels) ApplyToList(opts *ListOptions) {
+	sel := labels.NewSelector()
+	for _, label := range m {
+		r, err := labels.NewRequirement(label, selection.Exists, nil)
+		if err == nil {
+			sel = sel.Add(*r)
+		}
+	}
+	opts.LabelSelector = sel
+}
+
+func (m ContainsLabels) ApplyToDeleteAllOf(opts *DeleteAllOfOptions) {
+	m.ApplyToList(&opts.ListOptions)
+}
+
 // MatchingLabelsSelector filters the list/delete operation on the given label
 // selector (or index in the case of cached lists). A struct is used because
 // labels.Selector is an interface, which cannot be aliased.