Define Docker Image Arch

Hi

Can someone please explain how you set the architecture type and required os for a docker image.

I have built an image to run on a raspberry pi zero w (armv6) and it runs ok, but the file on docker says its for amd64. I have searched and can find nothing relevant for this. Its not a multi-arch image.

So all I would like to know is what I have to do to set the image arch correctly.

thanks in advance