I've been working on getting docker:dind-rootless working on CentOS 7.7 and ran into an issue because of overlay detection. The docker:dind-rootless image apparently assumes the host OS supports overlay (there's even a TODO) which then causes the image to fail when launching child containers with a "operation not permitted" referencing the overlay mount command.

My workaround is passing --storage-driver=vfs on the docker run but I believe that the image should auto-detect overlay support or have documentation about the above flag.