kubectl: scale down based on ready during rolling updates

pkg/kubectl/rolling_updater.go

@@ -113,10 +113,8 @@ type RollingUpdater struct {
 	getOrCreateTargetController func(controller *api.ReplicationController, sourceId string) (*api.ReplicationController, bool, error)
 	// cleanup performs post deployment cleanup tasks for newRc and oldRc.
 	cleanup func(oldRc, newRc *api.ReplicationController, config *RollingUpdaterConfig) error
-	// waitForReadyPods should block until there are >0 total pods ready amongst
-	// the old and new controllers, and should return the amount of old and new
-	// ready.
-	waitForReadyPods func(interval, timeout time.Duration, oldRc, newRc *api.ReplicationController) (int, int, error)
+	// getReadyPods returns the amount of old and new ready pods.
+	getReadyPods func(oldRc, newRc *api.ReplicationController) (int, int, error)
 }
 
 // NewRollingUpdater creates a RollingUpdater from a client.
@@ -128,7 +126,7 @@ func NewRollingUpdater(namespace string, client client.Interface) *RollingUpdate
 	// Inject real implementations.
 	updater.scaleAndWait = updater.scaleAndWaitWithScaler
 	updater.getOrCreateTargetController = updater.getOrCreateTargetControllerWithClient
-	updater.waitForReadyPods = updater.pollForReadyPods
+	updater.getReadyPods = updater.readyPods
 	updater.cleanup = updater.cleanupWithClients
 	return updater
 }
@@ -299,7 +297,7 @@ func (r *RollingUpdater) scaleUp(newRc, oldRc *api.ReplicationController, origin
 	return scaledRc, nil
 }
 
-// scaleDown scales down oldRc to 0 at whatever increment possible given the
+// scaleDown scales down oldRc to 0 at whatever decrement possible given the
 // thresholds defined on the config. scaleDown will safely no-op as necessary
 // when it detects redundancy or other relevant conditions.
 func (r *RollingUpdater) scaleDown(newRc, oldRc *api.ReplicationController, desired, minAvailable, maxUnavailable, maxSurge int, config *RollingUpdaterConfig) (*api.ReplicationController, error) {
@@ -307,15 +305,19 @@ func (r *RollingUpdater) scaleDown(newRc, oldRc *api.ReplicationController, desi
 	if oldRc.Spec.Replicas == 0 {
 		return oldRc, nil
 	}
-	// Block until there are any pods ready.
-	_, newAvailable, err := r.waitForReadyPods(config.Interval, config.Timeout, oldRc, newRc)
+	// Get ready pods. We shouldn't block, otherwise in case both old and new
+	// pods are unavailable then the rolling update process blocks.
+	// Timeout-wise we are already covered by the progress check.
+	_, newAvailable, err := r.getReadyPods(oldRc, newRc)
 	if err != nil {
 		return nil, err
 	}
 	// The old controller is considered as part of the total because we want to
 	// maintain minimum availability even with a volatile old controller.
 	// Scale down as much as possible while maintaining minimum availability
-	decrement := oldRc.Spec.Replicas + newAvailable - minAvailable
+	allPods := oldRc.Spec.Replicas + newRc.Spec.Replicas
+	newUnavailable := newRc.Spec.Replicas - newAvailable
+	decrement := allPods - minAvailable - newUnavailable
 	// The decrement normally shouldn't drop below 0 because the available count
 	// always starts below the old replica count, but the old replica count can
 	// decrement due to externalities like pods death in the replica set. This
@@ -360,40 +362,34 @@ func (r *RollingUpdater) scaleAndWaitWithScaler(rc *api.ReplicationController, r
 	return r.c.ReplicationControllers(rc.Namespace).Get(rc.Name)
 }
 
-// pollForReadyPods polls oldRc and newRc each interval and returns the old
-// and new ready counts for their pods. If a pod is observed as being ready,
-// it's considered ready even if it later becomes notReady.
-func (r *RollingUpdater) pollForReadyPods(interval, timeout time.Duration, oldRc, newRc *api.ReplicationController) (int, int, error) {
+// readyPods returns the old and new ready counts for their pods.
+// If a pod is observed as being ready, it's considered ready even
+// if it later becomes notReady.
+func (r *RollingUpdater) readyPods(oldRc, newRc *api.ReplicationController) (int, int, error) {
 	controllers := []*api.ReplicationController{oldRc, newRc}
 	oldReady := 0
 	newReady := 0
-	err := wait.Poll(interval, timeout, func() (done bool, err error) {
-		anyReady := false
-		for _, controller := range controllers {
-			selector := labels.Set(controller.Spec.Selector).AsSelector()
-			options := api.ListOptions{LabelSelector: selector}
-			pods, err := r.c.Pods(controller.Namespace).List(options)
-			if err != nil {
-				return false, err
-			}
-			for _, pod := range pods.Items {
-				if api.IsPodReady(&pod) {
-					switch controller.Name {
-					case oldRc.Name:
-						oldReady++
-					case newRc.Name:
-						newReady++
-					}
-					anyReady = true
+
+	for i := range controllers {
+		controller := controllers[i]
+		selector := labels.Set(controller.Spec.Selector).AsSelector()
+		options := api.ListOptions{LabelSelector: selector}
+		pods, err := r.c.Pods(controller.Namespace).List(options)
+		if err != nil {
+			return 0, 0, err
+		}
+		for _, pod := range pods.Items {
+			if api.IsPodReady(&pod) {
+				switch controller.Name {
+				case oldRc.Name:
+					oldReady++
+				case newRc.Name:
+					newReady++
 				}
 			}
 		}
-		if anyReady {
-			return true, nil
-		}
-		return false, nil
-	})
-	return oldReady, newReady, err
+	}
+	return oldReady, newReady, nil
 }
 
 // getOrCreateTargetControllerWithClient looks for an existing controller with

pkg/kubectl/rolling_updater_test.go

@@ -634,6 +634,27 @@ Scaling up foo-v2 from 0 to 2, scaling down foo-v1 from 30 to 0 (keep 1 pods ava
 Scaling foo-v1 down to 1
 Scaling foo-v2 up to 2
 Scaling foo-v1 down to 0
+`,
+		},
+		{
+			name:        "2->2 1/0 blocked oldRc",
+			oldRc:       oldRc(2, 2),
+			newRc:       newRc(0, 2),
+			newRcExists: false,
+			maxUnavail:  intstr.FromInt(1),
+			maxSurge:    intstr.FromInt(0),
+			expected: []interface{}{
+				down{oldReady: 1, newReady: 0, to: 1},
+				up{1},
+				down{oldReady: 1, newReady: 1, to: 0},
+				up{2},
+			},
+			output: `Created foo-v2
+Scaling up foo-v2 from 0 to 2, scaling down foo-v1 from 2 to 0 (keep 1 pods available, don't exceed 2 pods)
+Scaling foo-v1 down to 1
+Scaling foo-v2 up to 1
+Scaling foo-v1 down to 0
+Scaling foo-v2 up to 2
 `,
 		},
 	}
@@ -685,10 +706,10 @@ Scaling foo-v1 down to 0
 				expected := -1
 				switch {
 				case rc == test.newRc:
-					t.Logf("scaling up %s:%d", rc.Name, rc.Spec.Replicas)
+					t.Logf("scaling up %s to %d", rc.Name, rc.Spec.Replicas)
 					expected = next(&upTo)
 				case rc == test.oldRc:
-					t.Logf("scaling down %s:%d", rc.Name, rc.Spec.Replicas)
+					t.Logf("scaling down %s to %d", rc.Name, rc.Spec.Replicas)
 					expected = next(&downTo)
 				}
 				if expected == -1 {
@@ -709,13 +730,13 @@ Scaling foo-v1 down to 0
 			},
 		}
 		// Set up a mock readiness check which handles the test assertions.
-		updater.waitForReadyPods = func(interval, timeout time.Duration, oldRc, newRc *api.ReplicationController) (int, int, error) {
+		updater.getReadyPods = func(oldRc, newRc *api.ReplicationController) (int, int, error) {
 			// Return simulated readiness, and throw an error if this call has no
 			// expectations defined.
 			oldReady := next(&oldReady)
 			newReady := next(&newReady)
 			if oldReady == -1 || newReady == -1 {
-				t.Fatalf("unexpected waitForReadyPods call for:\noldRc: %+v\nnewRc: %+v", oldRc, newRc)
+				t.Fatalf("unexpected getReadyPods call for:\noldRc: %+v\nnewRc: %+v", oldRc, newRc)
 			}
 			return oldReady, newReady, nil
 		}
@@ -759,7 +780,7 @@ func TestUpdate_progressTimeout(t *testing.T) {
 			return nil
 		},
 	}
-	updater.waitForReadyPods = func(interval, timeout time.Duration, oldRc, newRc *api.ReplicationController) (int, int, error) {
+	updater.getReadyPods = func(oldRc, newRc *api.ReplicationController) (int, int, error) {
 		// Coerce a timeout by pods never becoming ready.
 		return 0, 0, nil
 	}
@@ -812,7 +833,7 @@ func TestUpdate_assignOriginalAnnotation(t *testing.T) {
 		cleanup: func(oldRc, newRc *api.ReplicationController, config *RollingUpdaterConfig) error {
 			return nil
 		},
-		waitForReadyPods: func(interval, timeout time.Duration, oldRc, newRc *api.ReplicationController) (int, int, error) {
+		getReadyPods: func(oldRc, newRc *api.ReplicationController) (int, int, error) {
 			return 1, 1, nil
 		},
 	}
@@ -1442,7 +1463,7 @@ func TestAddDeploymentHash(t *testing.T) {
 	}
 }
 
-func TestRollingUpdater_pollForReadyPods(t *testing.T) {
+func TestRollingUpdater_readyPods(t *testing.T) {
 	mkpod := func(owner *api.ReplicationController, ready bool) *api.Pod {
 		labels := map[string]string{}
 		for k, v := range owner.Spec.Selector {
@@ -1538,7 +1559,7 @@ func TestRollingUpdater_pollForReadyPods(t *testing.T) {
 			ns: "default",
 			c:  client,
 		}
-		oldReady, newReady, err := updater.pollForReadyPods(time.Millisecond, time.Second, test.oldRc, test.newRc)
+		oldReady, newReady, err := updater.readyPods(test.oldRc, test.newRc)
 		if err != nil {
 			t.Errorf("unexpected error: %v", err)
 		}