Configure cgroups mounts as shared and mount bpffs by default

[chancez]

I work for @isovalent and so I'm always looking for ways to make installing cilium easier. I've been making some progress on that in #1976 for example.

One thing that would make it even easier to install cilium is making /sys/fs/cgroup a shared mount, and mounting the BPF at /sys/fs/bpf and also making it a shared mount. This is necessary because the cilium-agent container mounts these using host mounts, and it requires them to be shared mounts for this work.

Today I've accomplished this with a override.yaml for Lima:

provision:
  - mode: system
    script: |
      #!/bin/sh
      set -e

      # needed for cilium
      mount bpffs -t bpf /sys/fs/bpf
      mount --make-shared /sys/fs/bpf
      mount --make-shared /sys/fs/cgroup

This works well, but requires providing additional instructions for users, and it doesn't work for WSL.

The other benefit of this is that it would enable using BPF on rancher-desktop with other BPF tools besides cilium, that run in containers, so it's not entirely cilium specific.

[jandubois]

One thing that would make it even easier to install cilium is making /sys/fs/cgroup a shared mount, and mounting the BPF at /sys/fs/bpf and also making it a shared mount.

This sounds fine to me. It could just be added to the RD provisioning scripts (and wsl-init for Windows). Just file a PR for it!

[chancez]

Sounds good to me!