question about podman cgroup init process

[calvin2021y]

I try to start a rootless podman container by direct start by crun.

When I use podman inside podman (non-root user) with privileged option, I can move pid 1 into a new create cgroup.

podman --privileged -it --rm --systemd=false  mgoltzsche/podman:latest ash
cat /sys/fs/cgroup/cgroup.procs 
1
2
mkdir /sys/fs/cgroup/init
echo 1 > /sys/fs/cgroup/init/cgroup.procs 
cat /sys/fs/cgroup/init/cgroup.procs 

when I try start a container by crun with config.json, and from a cgroup like this:

cat /proc/self/cgroup
0::/user.slice/user-1001.slice/[email protected]/user.slice/test.scope
crun --rootless=/tmp/test run test
# now int container shell
mkdir /sys/fs/cgroup/init
echo 1 > /sys/fs/cgroup/init/cgroup.procs 
cat /sys/fs/cgroup/init/cgroup.procs 
echo: write error: Not supported
cat /sys/fs/cgroup/cgroup.procs 
0
1
2

I am not sure why my crun container /sys/fs/cgroup/cgroup.procs has a pid 0, how can I avoid this by adust crun argument or config.json?

podman need move pid 1 into init to start work in rootless mode, echo: write error: Not supported error block this step.

[calvin2021y]

after use runc replace crun inside container, and other adjust the problem is fixed.

not sure why crun not work.

[rhatdan]

@giuseppe @flouthoc PTAL