Fix rollback for missing resources

Signed-off-by: Feruzjon Muyassarov <feruzjon.muyassarov@est.tech>
(cherry picked from commit 374aeb4b4e)

pkg/kube/client.go

@@ -557,7 +557,32 @@ func (c *Client) update(originals, targets ResourceList, createApplyFunc CreateA
 		original := originals.Get(target)
 		if original == nil {
 			kind := target.Mapping.GroupVersionKind.Kind
-			return fmt.Errorf("original object %s with the name %q not found", kind, target.Name)
+
+			slog.Warn("resource exists on cluster but not in original release, using cluster state as baseline",
+				"namespace", target.Namespace, "name", target.Name, "kind", kind)
+
+			currentObj, err := helper.Get(target.Namespace, target.Name)
+			if err != nil {
+				return fmt.Errorf("original object %s with the name %q not found", kind, target.Name)
+			}
+
+			// Create a temporary Info with the current cluster state to use as "original"
+			currentInfo := &resource.Info{
+				Client:    target.Client,
+				Mapping:   target.Mapping,
+				Namespace: target.Namespace,
+				Name:      target.Name,
+				Object:    currentObj,
+			}
+
+			if err := updateApplyFunc(currentInfo, target); err != nil {
+				updateErrors = append(updateErrors, err)
+			}
+
+			// Because we check for errors later, append the info regardless
+			res.Updated = append(res.Updated, target)
+
+			return nil
 		}
 
 		if err := updateApplyFunc(original, target); err != nil {
@@ -595,7 +620,9 @@ func (c *Client) update(originals, targets ResourceList, createApplyFunc CreateA
 		if err := deleteResource(info, metav1.DeletePropagationBackground); err != nil {
 			c.Logger().Debug("failed to delete resource", "namespace", info.Namespace, "name", info.Name, "kind", info.Mapping.GroupVersionKind.Kind, slog.Any("error", err))
 			if !apierrors.IsNotFound(err) {
-				updateErrors = append(updateErrors, fmt.Errorf("failed to delete resource %s: %w", info.Name, err))
+				updateErrors = append(updateErrors, fmt.Errorf(
+					"failed to delete resource namespace=%s, name=%s, kind=%s: %w",
+					info.Namespace, info.Name, info.Mapping.GroupVersionKind.Kind, err))
 			}
 			continue
 		}

pkg/kube/client_test.go

@@ -411,7 +411,25 @@ func TestUpdate(t *testing.T) {
 				"/namespaces/default/pods/forbidden:GET",
 				"/namespaces/default/pods/forbidden:DELETE",
 			),
-			ExpectedError: "failed to delete resource forbidden:",
+			ExpectedError: "failed to delete resource namespace=default, name=forbidden, kind=Pod:",
+		},
+		"rollback after failed upgrade with removed resource": {
+			// Simulates rollback scenario:
+			// - Revision 1 had "newpod"
+			// - Revision 2 removed "newpod" but upgrade failed (OriginalPods is empty)
+			// - Cluster still has "newpod" from Revision 1
+			// - Rolling back to Revision 1 (TargetPods with "newpod") should succeed
+			OriginalPods:                 v1.PodList{},         // Revision 2 (failed) - resource was removed
+			TargetPods:                   newPodList("newpod"), // Revision 1 - rolling back to this
+			ThreeWayMergeForUnstructured: false,
+			ServerSideApply:              true,
+			ExpectedActions: []string{
+				"/namespaces/default/pods/newpod:GET",   // Check if resource exists
+				"/namespaces/default/pods/newpod:GET",   // Get current state (first call in update path)
+				"/namespaces/default/pods/newpod:GET",   // Get current cluster state to use as baseline
+				"/namespaces/default/pods/newpod:PATCH", // Update using cluster state as baseline
+			},
+			ExpectedError: "",
 		},
 	}
 
@@ -428,6 +446,10 @@ func TestUpdate(t *testing.T) {
 				p, m := req.URL.Path, req.Method
 
 				switch {
+				case p == "/namespaces/default/pods/newpod" && m == http.MethodGet:
+					return newResponse(http.StatusOK, &listTarget.Items[0])
+				case p == "/namespaces/default/pods/newpod" && m == http.MethodPatch:
+					return newResponse(http.StatusOK, &listTarget.Items[0])
 				case p == "/namespaces/default/pods/starfish" && m == http.MethodGet:
 					return newResponse(http.StatusOK, &listOriginal.Items[0])
 				case p == "/namespaces/default/pods/otter" && m == http.MethodGet:
@@ -519,9 +541,23 @@ func TestUpdate(t *testing.T) {
 				require.NoError(t, err)
 			}
 
-			assert.Len(t, result.Created, 1, "expected 1 resource created, got %d", len(result.Created))
-			assert.Len(t, result.Updated, 2, "expected 2 resource updated, got %d", len(result.Updated))
-			assert.Len(t, result.Deleted, 1, "expected 1 resource deleted, got %d", len(result.Deleted))
+			// Special handling for the rollback test case
+			if name == "rollback after failed upgrade with removed resource" {
+				assert.Len(t, result.Created, 0, "expected 0 resource created, got %d", len(result.Created))
+				assert.Len(t, result.Updated, 1, "expected 1 resource updated, got %d", len(result.Updated))
+				assert.Len(t, result.Deleted, 0, "expected 0 resource deleted, got %d", len(result.Deleted))
+			} else {
+				assert.Len(t, result.Created, 1, "expected 1 resource created, got %d", len(result.Created))
+				assert.Len(t, result.Updated, 2, "expected 2 resource updated, got %d", len(result.Updated))
+				assert.Len(t, result.Deleted, 1, "expected 1 resource deleted, got %d", len(result.Deleted))
+			}
+
+			if tc.ExpectedError != "" {
+				require.Error(t, err)
+				require.Contains(t, err.Error(), tc.ExpectedError)
+			} else {
+				require.NoError(t, err)
+			}
 
 			actions := []string{}
 			for _, action := range client.Actions {