Sometimes you are needed to be got what of consists of in the docker image. So you can convert this is an image to archive and unpack this is an archive to a file system.
# For understanding
docker build --tag site:latest .
docker tag site:latest _name/site:latest
docker push _name/site:latest
# This is keyvalues strings
docker run -d -p 3000:3000 --name container_name site:latest
docker export container_name > contents.tar
