I would like to call out the moron who decided to control docker through HTTP when the maximum time the server can take to finish the task is longer than the HTTP timeout.
If you expect things might time out, you don't use a HTTP request. You use a resource and poll it, or Websockets, or possibly SSE.
Shoehorning your API into a frame that obviously doesn't fit doesn't help anyone. Just admit that you don't know what HTTP is and use a regular TCP socket with regular pings.