How can I stop docker from truncating long filenames when I copy from a container?

Question

I've noticed that my tar.gz files that are getting uploaded have files inside them that have truncated filenames. When I view the build log, the files are getting written with the full filename (same outcome when building locally). The files are then copied out with docker cp into a tar file, gzipped, and uploaded to a server. If I download the artifact from the server, the filenames of long files have been truncated at right around 100 characters long, including path (eg, files in the js folder end up being 1 character longer than files in the css folder).

Is this a docker issue, or could docker be using a bad tar library? What can I do to work around this without changing the filenames?

Answer 1

If the container includes tar try

docker exec container_id tar -C /path/to/tar -cf - . > local.tar