OCPBUGS-86009: Fix dns operator reporting Progressing=True on scale up

The cluster-dns-operator was incorrectly reporting Progressing=True
during normal cluster scale up events. This was caused by the
computeDNSProgressingCondition checking UpdatedNumberScheduled against
DesiredNumberScheduled. When a new node is added, DesiredNumberScheduled
increases immediately, but UpdatedNumberScheduled lags until the pod is
running, causing the operator to appear to be rolling out.

This commit introduces an isDaemonSetRollingOut helper, modeled after
similar logic in the cluster-ingress-operator. It checks if the
DaemonSet Generation matches ObservedGeneration, and checks if
UpdatedNumberScheduled is less than CurrentNumberScheduled. If not, the
operator is simply scaling and should not report Progressing=True.

Author: bentito

pkg/operator/controller/dns_status.go

@@ -208,7 +208,9 @@ func computeDNSProgressingCondition(oldCondition *operatorv1.OperatorCondition,
 		have := dnsDaemonset.Status.UpdatedNumberScheduled // num of nodes running the updated pod.
 		// It's progressing when have < want.  If have >= want, that's okay.
 		if have < want {
-			messages = append(messages, fmt.Sprintf("Have %d up-to-date DNS pods, want %d.", have, want))
+			if isDaemonSetRollingOut(dnsDaemonset) {
+				messages = append(messages, fmt.Sprintf("Have %d up-to-date DNS pods, want %d.", have, want))
+			}
 		}
 
 		haveSelector := dnsDaemonset.Spec.Template.Spec.NodeSelector
@@ -231,7 +233,9 @@ func computeDNSProgressingCondition(oldCondition *operatorv1.OperatorCondition,
 
 		// It's progressing when have < want.  If have >= want, that's okay.
 		if have < want {
-			messages = append(messages, fmt.Sprintf("Have %d available node-resolver pods, want %d.", have, want))
+			if isDaemonSetRollingOut(nodeResolverDaemonset) {
+				messages = append(messages, fmt.Sprintf("Have %d available node-resolver pods, want %d.", have, want))
+			}
 		}
 	}
 	if len(messages) != 0 {
@@ -350,3 +354,16 @@ func lastTransitionTimeIsRecent(currTime, prevTime time.Time, toleration time.Du
 		return elapsed <= toleration
 	}
 }
+
+// isDaemonSetRollingOut determines if the DaemonSet is currently in a rollout state
+// (i.e., actively replacing old pods with new ones or applying a new configuration)
+// versus simply stabilizing (e.g., waiting for pods to start after a node reboot or scale up).
+func isDaemonSetRollingOut(ds *appsv1.DaemonSet) bool {
+	if ds.Generation != ds.Status.ObservedGeneration {
+		return true
+	}
+	if ds.Status.UpdatedNumberScheduled < ds.Status.CurrentNumberScheduled {
+		return true
+	}
+	return false
+}

pkg/operator/controller/dns_status_test.go

@@ -111,6 +111,7 @@ func TestDNSStatusConditions(t *testing.T) {
 					DesiredNumberScheduled: tc.inputs.desireDNS,
 					NumberAvailable:        tc.inputs.availDNS,
 					UpdatedNumberScheduled: tc.inputs.updatedDNS,
+					CurrentNumberScheduled: tc.inputs.desireDNS,
 				},
 			}
 			dnsDaemonset.Spec.Template.Spec.NodeSelector = nodeSelectorForDNS(&operatorv1.DNS{})
@@ -132,6 +133,7 @@ func TestDNSStatusConditions(t *testing.T) {
 					DesiredNumberScheduled: tc.inputs.desireNR,
 					NumberAvailable:        tc.inputs.availNR,
 					UpdatedNumberScheduled: tc.inputs.updatedNR,
+					CurrentNumberScheduled: tc.inputs.desireNR,
 				},
 			}
 		}
@@ -240,6 +242,7 @@ func TestComputeDNSDegradedCondition(t *testing.T) {
 			Status: appsv1.DaemonSetStatus{
 				DesiredNumberScheduled: int32(desired),
 				NumberAvailable:        int32(available),
+				CurrentNumberScheduled: int32(desired),
 			},
 		}
 	}
@@ -471,6 +474,7 @@ func TestComputeDNSProgressingCondition(t *testing.T) {
 			Status: appsv1.DaemonSetStatus{
 				DesiredNumberScheduled: int32(desired),
 				NumberAvailable:        int32(available),
+				CurrentNumberScheduled: int32(desired),
 				UpdatedNumberScheduled: int32(updated),
 			},
 		}
@@ -638,6 +642,7 @@ func TestSkippingStatusUpdates(t *testing.T) {
 			Status: appsv1.DaemonSetStatus{
 				DesiredNumberScheduled: int32(desired),
 				NumberAvailable:        int32(available),
+				CurrentNumberScheduled: int32(desired),
 				UpdatedNumberScheduled: int32(updated),
 			},
 		}