fix: remove resourceVersion from ssd (#27406)

Signed-off-by: Peter Jiang <peterjiang823@gmail.com>

gitops-engine/pkg/diff/diff.go

@@ -188,6 +188,7 @@ func serverSideDiff(config, live *unstructured.Unstructured, opts ...Option) (*D
 
 	Normalize(predictedLive, opts...)
 	unstructured.RemoveNestedField(predictedLive.Object, "metadata", "managedFields")
+	unstructured.RemoveNestedField(predictedLive.Object, "metadata", "resourceVersion")
 
 	predictedLiveBytes, err := json.Marshal(predictedLive)
 	if err != nil {
@@ -196,6 +197,7 @@ func serverSideDiff(config, live *unstructured.Unstructured, opts ...Option) (*D
 
 	Normalize(live, opts...)
 	unstructured.RemoveNestedField(live.Object, "metadata", "managedFields")
+	unstructured.RemoveNestedField(live.Object, "metadata", "resourceVersion")
 	liveBytes, err := json.Marshal(live)
 	if err != nil {
 		return nil, fmt.Errorf("error marshaling live resource %s/%s: %w", config.GetKind(), config.GetName(), err)

gitops-engine/pkg/diff/diff_test.go

@@ -1165,6 +1165,54 @@ func TestServerSideDiff(t *testing.T) {
 		assert.Empty(t, liveDeploy.Annotations[AnnotationLastAppliedConfig])
 	})
 
+	t.Run("will not report diff for mismatched resourceVersion", func(t *testing.T) {
+		// given
+		t.Parallel()
+		predictedLiveJSON := `{
+			"apiVersion": "apps/v1",
+			"kind": "Deployment",
+			"metadata": {
+				"name": "my-deploy",
+				"namespace": "default",
+				"resourceVersion": "99999",
+				"managedFields": [{"manager":"argocd-controller","operation":"Apply","fieldsType":"FieldsV1","fieldsV1":{"f:spec":{"f:replicas":{}}}}]
+			},
+			"spec": {"replicas": 1}
+		}`
+		liveState := StrToUnstructured(`{
+			"apiVersion": "apps/v1",
+			"kind": "Deployment",
+			"metadata": {
+				"name": "my-deploy",
+				"namespace": "default",
+				"resourceVersion": "12345",
+				"managedFields": [{"manager":"argocd-controller","operation":"Apply","fieldsType":"FieldsV1","fieldsV1":{"f:spec":{"f:replicas":{}}}}]
+			},
+			"spec": {"replicas": 1}
+		}`)
+		desiredState := StrToUnstructured(`{
+			"apiVersion": "apps/v1",
+			"kind": "Deployment",
+			"metadata": {
+				"name": "my-deploy",
+				"namespace": "default"
+			},
+			"spec": {"replicas": 1}
+		}`)
+		opts := buildOpts(predictedLiveJSON)
+		opts = append(opts, WithIgnoreMutationWebhook(false))
+
+		// when
+		result, err := serverSideDiff(desiredState, liveState, opts...)
+
+		// then
+		require.NoError(t, err)
+		assert.NotNil(t, result)
+		assert.False(t, result.Modified, "mismatched resourceVersion should not cause a diff")
+		assert.NotContains(t, string(result.PredictedLive), "resourceVersion")
+		assert.NotContains(t, string(result.NormalizedLive), "resourceVersion")
+	})
+
 	t.Run("will detect ConfigMap data key removal", func(t *testing.T) {
 		// given
 		t.Parallel()