Docker Hub
https://hub.docker.com/r/existdb/existdbImages will continue to be available via DockerHub under the old address, but the build will move to eXist-db's core repo. This repository holds the source files for building a minimal docker image of the exist-db xml database, automatically building from eXist's source code repo. It uses Google Cloud Platforms "Distroless" Docker Images.
docker cp | Docker Documentation
docs.docker.com › engine › referenceThe docker cp utility copies the contents of SRC_PATH to the DEST_PATH . You can copy from the container’s file system to the local machine or the reverse, from the local filesystem to the container. If - is specified for either the SRC_PATH or DEST_PATH, you can also stream a tar archive from STDIN or to STDOUT.