Fail to start cilium (container mount-bpf-fs) on Alpine Linux + k0s because "not a shared mount"

[Raboo]

Fail to start cilium (container mount-bpf-fs) on Alpine Linux + k0s because "not a shared mount"

[youngnick]

Thanks for this issue @Raboo, but from a quick google it seems like this issue is relatively common for rootless or other non-full Docker instalattions. Some links I found that show some more info:

https://unix.stackexchange.com/questions/117414/confusion-about-mount-options#
nextcloud/all-in-one#3177 as well.

Because /sys/fs/bpf is needed by many things, I don't think that we can get around the requirement that it needs to be a shared mount.

To be honest, I'm not sure what Cilium can do to help here, without that mount being set to shared Cilium won't be able to write to that filesystem properly.

[Raboo]

After some extensive searching I finally found the cause. It doesn't have anything to do with rootless or docker.
It's a default in Alpine Linux to make it more secure. It doesn't mount file systems as "shared".
Someone did a nice writeup in a blog post about this issue in 2021 https://www.adyxax.org/blog/2021/07/30/private-and-shared-mounts/.

k3d made a work-around for this k3d-io/k3d#1268.
OpenRC has a issue and a open pr to make "shared" mounting as an option OpenRC/openrc#526.
And the issue has also been reported to Alpine Linux issue tracker https://gitlab.alpinelinux.org/alpine/aports/-/issues/13565.

So this is more of a Alpine/OpenRC issue. Should be handled by them.