Hello
I tried to look for any requests to the ghost api schedules/posts, but couldn’t find anything. I did figure out the secret (I think). I managed to run that URL from inside the docker container.
It works when I use localhost:2368 (the port Ghost is running on). But it doesn’t work when I use https://:443.
I don’t exactly know why there is a timeout though: I would think this would go to my docker container, come in via the nginx container and then go to the ghost container. But instead it just times out. I can ping the server from inside the docker container with the public IP address.
But why wouldn’t Ghost call it’s own API via the localhost? Is this something I can influence through configuration?
When I have some time, I may have a look in the code and try and understand what is happening. But maybe you know more, more quickly 
Thanks a lot for the assistance and Ghost!