Rootless podman: Error: kernel does not support overlay fs

Project Discussion
1

I’m trying to create an image storage on a shared directory, to be used with additionalimagestores.
Following Exploring additional image stores in Podman, I’m running:

$ podman --root ./rootless pull ubuntu:20.04
Error: kernel does not support overlay fs: unable to create kernel-style whiteout: operation not permitted

Running sudo podman --root ./rootless pull works, but then the created image storage cannot be used by a rootless podman.
When setting additionalimagestores to point to a readonly share with the image storage created with sudo podman, I’m getting:

$ podman images
REPOSITORY                                 TAG         IMAGE ID      CREATED      SIZE        R/O
docker.io/library/ubuntu                   20.04       3bc6e9f30f51  7 days ago   75.2 MB     true

$ podman run --rm -it ubuntu:20.04
Error: creating /etc/mtab symlink: permission denied

Rootless podman gives this error, but sudo podman run --rm -it ubuntu:20.04 works here.

As a workaround I can run everything with sudo, but it’s not clear to me what is the issue with rootless podman here.

I’m running podman 3.4.2 on Ubuntu 20.04.4, but also tried containerized podman from quay.io/podman/stable.

2

It looks like you’re using podman on Ubuntu but you are in the Fedora CoreOS tag on the Fedora discussion board.

Can you reach out to the podman upstream community?

3

Good point, thanks.

I’ve opened a ticket Rootless podman pull: Error: kernel does not support overlay fs · Issue #15255 · containers/podman · GitHub

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