docker_image(
    name="book-creator",
    source="Dockerfile",
    dependencies=[
        "src/services/utils:util_files",
        ":service_files",
        "//:root",
        "//:git"
    ]
)

but this does not copy the .git folder

Not 100% sure, but I expect the issue here is that you didn't actually glob the files in the git folder. Try running

pants list ./.git/::

and I expect it will be empty. Change your sources field to

sources=["./.git/**/*"]

and try the

pants list

command again. If its still empty, then this may be due to

.gitignore

by default, pants ignores files that are .gitignored. One of the settings to change this is https://www.pantsbuild.org/prerelease/reference/global-options#pants_ignore_use_gitignore

Yeah, git state is completely ignored by Pants by default.

but then how do i copy the

.git

folder into my docker build stage? Because i need that for building the image

What are you actually trying to do? It seems odd to need local

.git

state inside a container