I'm attempting to Dockerize a fairly large Rails application, with the intent that during development I can just run docker build locally, while for deployment the CI server will do so.

In either case though it currently picks up things like the log directory, which can grow to several gigabytes of large files which I'm never going to want included in an image.

Is it possible to tell Docker to ignore that directory when uploading the build context? If not, what would be involved in making it happen? I've never used Go, but given a pointer in the right direction I'm happy to give it a shot.