The first rule of networking: You can't claim that a message had been received until you have heard the reply.

It's getting spooky

For a considerable number of days in a row, I randomly glance at my clock and it says 15:21.

Oracle is stocking me!!!!!!

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.

Is there a better way communicating between php and java than tcp? Because this was my first idea but i try everything on localhost and the request takes up to 3 seconds...

iptables -I INPUT -p tcp --dport 22 ! -s 192.168.1.0/24 -j RUSSIAN_WARSHIP_GO_F_URSELF

I'm trying to set up a websocket abstraction so I can reuse my comms code on BE and FE.