Fix DaemonSet misscheduled status not updating on node taint changes

Signed-off-by: xigang <[email protected]>

Author: xigang

pkg/controller/daemon/daemon_controller.go

@@ -1445,7 +1445,15 @@ func (dsc *DaemonSetsController) syncNodeUpdate(ctx context.Context, nodeName st
 		daemonPods := podsByDS[dsKey]
 		scheduled := len(daemonPods) > 0
 
-		if (shouldRun && !scheduled) || (!shouldContinueRunning && scheduled) {
+		// Enqueue DaemonSet for sync in the following scenarios:
+		// 1. (shouldRun && !scheduled): Node now meets scheduling requirements but no pod exists
+		//    - Need to create a new pod on this node
+		// 2. (!shouldContinueRunning && scheduled): Node no longer meets requirements but pod exists
+		//    - Need to delete the existing pod from this node
+		// 3. (scheduled && ds.Status.NumberMisscheduled > 0): DaemonSet pod exists and misscheduled count is nonzero.
+		//    - For example: a pod was scheduled before the node became unready and tainted; after the node becomes ready and taints are removed, the pod may now be valid again.
+		//    - Need to recalculate NumberMisscheduled to ensure the DaemonSet status accurately reflects the current scheduling state.
+		if (shouldRun && !scheduled) || (!shouldContinueRunning && scheduled) || (scheduled && ds.Status.NumberMisscheduled > 0) {
 			dsc.enqueueDaemonSet(ds)
 		}
 	}

pkg/controller/daemon/daemon_controller_test.go

@@ -2410,6 +2410,9 @@ func TestUpdateNode(t *testing.T) {
 		expectedEventsFunc func(strategyType apps.DaemonSetUpdateStrategyType) int
 		shouldEnqueue      bool
 		expectedCreates    func() int
+		// Indicates whether a DaemonSet pod was already present on the node before the node transitioned to Ready and schedulable state.
+		// (In other words, was the DaemonSet pod scheduled before the node lost its readiness / was tainted?)
+		preExistingPod bool
 	}{
 		{
 			test:    "Nothing changed, should not enqueue",
@@ -2422,6 +2425,7 @@ func TestUpdateNode(t *testing.T) {
 			}(),
 			shouldEnqueue:   false,
 			expectedCreates: func() int { return 0 },
+			preExistingPod:  false,
 		},
 		{
 			test:    "Node labels changed",
@@ -2434,6 +2438,7 @@ func TestUpdateNode(t *testing.T) {
 			}(),
 			shouldEnqueue:   true,
 			expectedCreates: func() int { return 0 },
+			preExistingPod:  false,
 		},
 		{
 			test: "Node taints changed",
@@ -2446,6 +2451,7 @@ func TestUpdateNode(t *testing.T) {
 			ds:              newDaemonSet("ds"),
 			shouldEnqueue:   true,
 			expectedCreates: func() int { return 0 },
+			preExistingPod:  false,
 		},
 		{
 			test:    "Node Allocatable changed",
@@ -2475,6 +2481,21 @@ func TestUpdateNode(t *testing.T) {
 			expectedCreates: func() int {
 				return 1
 			},
+			preExistingPod: false,
+		},
+		{
+			test:    "Pod transitions from misscheduled to scheduled due to node label change",
+			oldNode: newNode("node1", nil),
+			newNode: newNode("node1", simpleNodeLabel),
+			ds: func() *apps.DaemonSet {
+				ds := newDaemonSet("ds")
+				ds.Spec.Template.Spec.NodeSelector = simpleNodeLabel
+				ds.Status.NumberMisscheduled = 1
+				return ds
+			}(),
+			shouldEnqueue:   true,
+			expectedCreates: func() int { return 0 },
+			preExistingPod:  true,
 		},
 	}
 	for _, c := range cases {
@@ -2511,6 +2532,10 @@ func TestUpdateNode(t *testing.T) {
 			}
 			expectSyncDaemonSets(t, manager, c.ds, podControl, expectedCreates, 0, expectedEvents)
 
+			if c.preExistingPod {
+				addPods(manager.podStore, c.oldNode.Name, simpleDaemonSetLabel, c.ds, 1)
+			}
+
 			manager.enqueueDaemonSet = func(ds *apps.DaemonSet) {
 				if ds.Name == "ds" {
 					enqueued = true