From a57361561d883797886d50309500f34a2d859be3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Norman=20B=C3=B6wing?= <boewing@de.ibm.com>
Date: Mon, 26 Jan 2026 14:16:43 +0100
Subject: [PATCH] Reduce deployment updates

---
 pkg/reconciler/revision/cruds.go      | 10 +++++-----
 pkg/reconciler/revision/table_test.go | 10 ++++++++++
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/pkg/reconciler/revision/cruds.go b/pkg/reconciler/revision/cruds.go
index da5422a57016..4250b6fcfeeb 100644
--- a/pkg/reconciler/revision/cruds.go
+++ b/pkg/reconciler/revision/cruds.go
@@ -63,11 +63,6 @@ func (c *Reconciler) checkAndUpdateDeployment(ctx context.Context, rev *v1.Revis
 	// TODO(dprotaso): determine other immutable properties.
 	deployment.Spec.Selector = have.Spec.Selector
 
-	// If the spec we want is the spec we have, then we're good.
-	if equality.Semantic.DeepEqual(have.Spec, deployment.Spec) {
-		return have, nil
-	}
-
 	// Otherwise attempt an update (with ONLY the spec changes).
 	desiredDeployment := have.DeepCopy()
 	desiredDeployment.Spec = deployment.Spec
@@ -80,6 +75,11 @@ func (c *Reconciler) checkAndUpdateDeployment(ctx context.Context, rev *v1.Revis
 	desiredDeployment.Spec.Template.Labels = mergeMetadata(deployment.Spec.Template.Labels, have.Spec.Template.Labels)
 	desiredDeployment.Spec.Template.Annotations = mergeMetadata(deployment.Spec.Template.Annotations, have.Spec.Template.Annotations)
 
+	// If the spec we want is the spec we have, then we're good.
+	if equality.Semantic.DeepEqual(have.Spec, desiredDeployment.Spec) {
+		return have, nil
+	}
+
 	d, err := c.kubeclient.AppsV1().Deployments(deployment.Namespace).Update(ctx, desiredDeployment, metav1.UpdateOptions{})
 	if err != nil {
 		return nil, err
diff --git a/pkg/reconciler/revision/table_test.go b/pkg/reconciler/revision/table_test.go
index 6f1b5b011d5e..8d92163c6494 100644
--- a/pkg/reconciler/revision/table_test.go
+++ b/pkg/reconciler/revision/table_test.go
@@ -223,6 +223,16 @@ func TestReconcile(t *testing.T) {
 			Object: addDeploymentMetadata(deploy(t, "foo", "preserve-annotations"), false),
 		}},
 		Key: "foo/preserve-annotations",
+	}, {
+		Name: "do not update deployments with no spec changes",
+		Objects: []runtime.Object{
+			Revision("foo", "preserve-annotations",
+				WithLogURL, allUnknownConditions, withDefaultContainerStatuses(), WithRevisionObservedGeneration(1)),
+			pa("foo", "preserve-annotations", WithReachabilityUnknown),
+			addDeploymentMetadata(deploy(t, "foo", "preserve-annotations"), false),
+			image("foo", "preserve-annotations"),
+		},
+		Key: "foo/preserve-annotations",
 	}, {
 		Name: "failure updating deployment",
 		// Test that we handle an error updating the deployment properly.