F - pod deletion cost sorting

Author: brianberzins

reaper/options.go

@@ -168,6 +168,17 @@ func maxPods() (int, error) {
 	return v, nil
 }
 
+func getPodDeletionCost(pod v1.Pod) int32 {
+	// https://kubernetes.io/docs/concepts/workloads/controllers/replicaset/#pod-deletion-cost
+	costString, present := pod.ObjectMeta.Annotations["controller.kubernetes.io/pod-deletion-cost"]
+	if !present {
+		return 0
+	}
+	// per k8s doc: invalid values should be rejected by the API server
+	cost, _ := strconv.ParseInt(costString, 10, 32)
+	return int32(cost)
+}
+
 func podSortingStrategy() (func([]v1.Pod), error) {
 	sortingStrategy, present := os.LookupEnv(envPodSortingStrategy)
 	if !present {
@@ -203,6 +214,12 @@ func podSortingStrategy() (func([]v1.Pod), error) {
 				return pods[j].Status.StartTime.Unix() < pods[i].Status.StartTime.Unix()
 			})
 		}, nil
+	case "pod-deletion-cost":
+		return func(pods []v1.Pod) {
+			sort.Slice(pods, func(i, j int) bool {
+				return getPodDeletionCost(pods[i]) < getPodDeletionCost(pods[j])
+			})
+		}, nil
 	default:
 		return nil, errors.New("unknown pod sorting strategy")
 	}

reaper/options_test.go

@@ -31,14 +31,23 @@ func testPodList() []v1.Pod {
 			},
 			ObjectMeta: metav1.ObjectMeta{
 				Name:        "bearded-dragon",
-				Annotations: map[string]string{"example/key": "lizard"},
+				Annotations: map[string]string{"example/key": "lizard", "controller.kubernetes.io/pod-deletion-cost": "invalid"},
 			},
 		},
 		{
 			Status: v1.PodStatus{},
 			ObjectMeta: metav1.ObjectMeta{
 				Name:        "nil-start-time",
-				Annotations: map[string]string{"example/key": "lizard"},
+				Annotations: map[string]string{"example/key": "lizard", "controller.kubernetes.io/pod-deletion-cost": "-100"},
+			},
+		},
+		{
+			Status: v1.PodStatus{
+				StartTime: epocPlus(5 * time.Minute),
+			},
+			ObjectMeta: metav1.ObjectMeta{
+				Name:        "expensive",
+				Annotations: map[string]string{"example/key": "not-lizard", "controller.kubernetes.io/pod-deletion-cost": "500"},
 			},
 		},
 		{
@@ -325,7 +334,8 @@ func TestOptions(t *testing.T) {
 			sorter(subject)
 			assert.Equal(t, "corgi", subject[0].ObjectMeta.Name)
 			assert.Equal(t, "bearded-dragon", subject[1].ObjectMeta.Name)
-			assert.Equal(t, "nil-start-time", subject[2].ObjectMeta.Name)
+			assert.Equal(t, "expensive", subject[2].ObjectMeta.Name)
+			assert.Equal(t, "nil-start-time", subject[3].ObjectMeta.Name)
 			assert.ElementsMatch(t, testPodList(), subject)
 		})
 		t.Run("youngest-first", func(t *testing.T) {
@@ -336,9 +346,22 @@ func TestOptions(t *testing.T) {
 			assert.NoError(t, err)
 			subject := testPodList()
 			sorter(subject)
-			assert.Equal(t, "bearded-dragon", subject[0].ObjectMeta.Name)
-			assert.Equal(t, "corgi", subject[1].ObjectMeta.Name)
-			assert.Equal(t, "nil-start-time", subject[2].ObjectMeta.Name)
+			assert.Equal(t, "expensive", subject[0].ObjectMeta.Name)
+			assert.Equal(t, "bearded-dragon", subject[1].ObjectMeta.Name)
+			assert.Equal(t, "corgi", subject[2].ObjectMeta.Name)
+			assert.Equal(t, "nil-start-time", subject[3].ObjectMeta.Name)
+			assert.ElementsMatch(t, testPodList(), subject)
+		})
+		t.Run("pod-deletion-cost", func(t *testing.T) {
+			os.Clearenv()
+			os.Setenv(envPodSortingStrategy, "pod-deletion-cost")
+			sorter, err := podSortingStrategy()
+			assert.NotNil(t, sorter)
+			assert.NoError(t, err)
+			subject := testPodList()
+			sorter(subject)
+			assert.Equal(t, "nil-start-time", subject[0].ObjectMeta.Name)
+			assert.Equal(t, "expensive", subject[3].ObjectMeta.Name)
 			assert.ElementsMatch(t, testPodList(), subject)
 		})
 	})