Answer by Sami Wood for How to include files outside of Docker's build context?

I think as of earlier this year a feature was added in buildx to do just this.

If you have dockerfile 1.4+ and buildx 0.8+ you can do something like this:

docker buildx build --build-context othersource= ../something/something .

Then in your docker file you can use the from command to add the context

ADD –-from=othersource . /stuff

See this related post.