An even better variant would be "rsync -av" instead of scp, as this only copies files which are different or do not exist in the destination. By reversing source and destination, you can also copy data out of the container this way.
=== Copying data from your local machine the outside ===
From the local machine which has kubectl access to the cluster, you can directly copy data to and from the container using kubectl cp, which has a very similar syntax as scp: