[DanHulton]

You didn't specify, but it sounds like you're talking about from a development perspective, not a deployment one.

For development, you add a volume to the container and mount a location on that volume to a location on your host hard drive. There are different mount options that control which changes propagate in which direction, but two-way propagation is avaliable and works fine.

Once you have this set up, any changes you make on your host system are automatically reflected in your containers volume. It's very low stress and low overhead, honestly.