actions/overlay: Check source exists during recipe verification

If an overlay coming from the recipe directory doesn't
exist, the recipe exits during execution. Let's check
early if the overlay exists on the host filesystem.

Signed-off-by: Christopher Obbard <[email protected]>

Author: obbardc

actions/overlay_action.go

@@ -26,6 +26,7 @@ package actions
 
 import (
 	"fmt"
+	"os"
 	"path"
 
 	"github.com/go-debos/debos"
@@ -42,6 +43,13 @@ func (overlay *OverlayAction) Verify(context *debos.DebosContext) error {
 	if _, err := debos.RestrictedPath(context.Rootdir, overlay.Destination); err != nil {
 		return err
 	}
+
+	if len(overlay.Origin) == 0 {
+		if _, err := os.Stat(overlay.Source); err != nil {
+			return err
+		}
+	}
+
 	return nil
 }