Edit: Check @javabrett’s comment:
Upvoted despite this solution having a sunset. See answer regarding overlay-upperdir-on-overlay being disabled on 4.8 kernels and newer.
See: https://stackoverflow.com/a/50917037/644504
This is what I do:
On the host:
Load the directory as read only.
docker run --privileged -v /path/on/host:/path/on/client-read-only:ro -it ubuntu /bin/bash
On the client:
On the client use OverlayFS over the read-only directory mounted from the host.
mount -t overlayfs none -o lowerdir=/path/on/client-read-only,upperdir=/path/on/client /path/on/client
Then use /path/on/client to read/write the files.
Edit: if you have a 3.18+ kernel on your host, you may prefer using this on the client:
mount -t overlay overlay -o lowerdir=/path/on/client-read-only,upperdir=/path/on/client,workdir=/path/on/client-workdir /path/on/client
Which isn’t overlayfs. With overlayfs I had an issue regarding being unable to use rm. overlay solved this problem for me.