Rebased on master

pkg/executor/build.go

@@ -85,23 +85,41 @@ func DoBuild(opts *config.KanikoOptions) (v1.Image, error) {
 			if err := dockerCommand.ExecuteCommand(&imageConfig.Config, buildArgs); err != nil {
 				return nil, err
 			}
-			// Don't snapshot if it's not the final stage and not the final command
-			// Also don't snapshot if it's the final stage, not the final command, and single snapshot is set
-			if (!stage.FinalStage && !finalCmd) || (stage.FinalStage && !finalCmd && opts.SingleSnapshot) {
-				continue
-			}
-			// Now, we get the files to snapshot from this command and take the snapshot
 			snapshotFiles := dockerCommand.FilesToSnapshot()
-			if finalCmd {
-				snapshotFiles = nil
+			var contents []byte
+
+			// If this is an intermediate stage, we only snapshot for the last command and we
+			// want to snapshot the entire filesystem since we aren't tracking what was changed
+			// by previous commands.
+			if !stage.FinalStage {
+				if finalCmd {
+					contents, err = snapshotter.TakeSnapshotFS()
+				}
+			} else {
+				// If we are in single snapshot mode, we only take a snapshot once, after all
+				// commands have completed.
+				if opts.SingleSnapshot {
+					if finalCmd {
+						contents, err = snapshotter.TakeSnapshotFS()
+					}
+				} else {
+					// Otherwise, in the final stage we take a snapshot at each command. If we know
+					// the files that were changed, we'll snapshot those explicitly, otherwise we'll
+					// check if anything in the filesystem changed.
+					if snapshotFiles != nil {
+						contents, err = snapshotter.TakeSnapshot(snapshotFiles)
+					} else {
+						contents, err = snapshotter.TakeSnapshotFS()
+					}
+				}
 			}
-			contents, err := snapshotter.TakeSnapshot(snapshotFiles)
 			if err != nil {
-				return nil, err
+				return nil, fmt.Errorf("Error taking snapshot of files for command %s: %s", dockerCommand, err)
 			}
+
 			util.MoveVolumeWhitelistToWhitelist()
 			if contents == nil {
-				logrus.Info("No files were changed, appending empty layer to config.")
+				logrus.Info("No files were changed, appending empty layer to config. No layer added to image.")
 				continue
 			}
 			// Append the layer to the image