Base Image for Docker

In the past we experienced several problems with our docker containers, which is why I want to open the discussion for changing the base image.

Right now we are using alpine, Funkwhale 1.2 was based on Alpine 3.13. We tried updating to Alpine 3.15, which does not work if we want to support ldap. Alpine 3.15 ships OpenLDAP 2.6, which is not working with pyldap yet. For more details, visit https://github.com/python-ldap/python-ldap/issues/432

Unrelated to this issue we have problems with cryptography as well. They require some rust packages for build for their latest version, which is not available for Alpine currently. Further there are no prebuilt wheels available for arm64/armhf on Alpine, since they use musl instead of glibc.

All in all we might need to consider switching to a Debian based image, which might prevent us from having issues. Maybe this image turns out to be bigger than the current one, maybe we have other issues? I don't know right now. But Its worth a consideration.