What I need
I can sign Git commits locally on a host. I want to be able to sign Git commits in a running container too.
How can I share/mount GPG into a container or access from a container host's GPG?
What I tried
I tried to mount directories. Here is a not working Docker Compose:
volumes:
- ${HOME}/.gnupg/:/.gnupg/:ro
- /run/user/$(id -u)/:/run/user/$(id -u)/:ro
With these mounts I still get (executed inside a running container):
$ git commit -m "foobar"
error: gpg failed to sign the data
fatal: failed to write commit object