Fix second rolling update for MD rolloutAfter

Author: sm4ll-3gg

internal/controllers/machinedeployment/mdutil/util.go

@@ -499,9 +499,9 @@ func FindNewMachineSet(deployment *clusterv1.MachineDeployment, msList []*cluste
 		return matchingMachineSets[0], "", nil
 	}
 
-	// Pick the first matching MachineSet that has been created after RolloutAfter.
+	// Pick the first matching MachineSet that has been created at RolloutAfter or later.
 	for _, ms := range matchingMachineSets {
-		if ms.CreationTimestamp.After(deployment.Spec.RolloutAfter.Time) {
+		if ms.CreationTimestamp.Sub(deployment.Spec.RolloutAfter.Time) >= 0 {
 			return ms, "", nil
 		}
 	}

internal/controllers/machinedeployment/mdutil/util_test.go

@@ -423,6 +423,9 @@ func TestFindNewMachineSet(t *testing.T) {
 	msCreatedAfterRolloutAfter := generateMS(deployment)
 	msCreatedAfterRolloutAfter.CreationTimestamp = oneAfterRolloutAfter
 
+	msCreatedExactlyInRolloutAfter := generateMS(deployment)
+	msCreatedExactlyInRolloutAfter.CreationTimestamp = rolloutAfter
+
 	tests := []struct {
 		Name               string
 		deployment         clusterv1.MachineDeployment
@@ -485,6 +488,14 @@ func TestFindNewMachineSet(t *testing.T) {
 			reconciliationTime: &twoAfterRolloutAfter,
 			expected:           &msCreatedAfterRolloutAfter,
 		},
+		{
+			// https://github.com/kubernetes-sigs/cluster-api/issues/12260
+			Name:               "Get MachineSet created exactly in RolloutAfter if reconciliationTime > rolloutAfter",
+			deployment:         *deploymentWithRolloutAfter,
+			msList:             []*clusterv1.MachineSet{&msCreatedExactlyInRolloutAfter, &msCreatedTwoBeforeRolloutAfter},
+			reconciliationTime: &oneAfterRolloutAfter,
+			expected:           &msCreatedExactlyInRolloutAfter,
+		},
 		{
 			Name:               "Get MachineSet created after RolloutAfter if reconciliationTime is > rolloutAfter (inverse order in ms list)",
 			deployment:         *deploymentWithRolloutAfter,