skip full traceback for NotFound optional requests

slapos/recipe/request.py

@@ -179,7 +179,9 @@ class RequestOptional(Recipe):
   """
   def install(self):
     if self._raise_request_exception_formatted:
-      self.logger.warning('Optional request failed:')
+      self.logger.warning('Optional request failed.')
+      if not isinstance(self._raise_request_exception, slapmodule.NotFoundError):
+        # full traceback for optional 'not found' is too verbose and confusing
         self.logger.warning(self._raise_request_exception_formatted)
     elif self.failed is not None:
       # Check instance status to know if instance has been deployed