How to use nerdctl with buildkit OCI worker

[shashankk90]

I am trying to use nerdctl with buildkit OCI worker. This buildkit is started and runs independently of nerdctl and all the different setup tools provided in git repo.
I am running buildkit with rootlesskit buildkitd and it creates /run/user/1000/buildkit/buildkitd.sock for connections. If I try to run nerdctl it defaults to containerd I think.

/home/jovyan $ ./nerdctl
FATA[0000] rootless containerd not running? (hint: use `containerd-rootless-setuptool.sh install` to start rootless containerd): stat /run/user/1000/containerd-rootless: no such file or directory

I tried running buildkit with rootlesskit buildkitd --addr unix:///run/user/1000/containerd-rootless/buildkit.sock but then nerdctl looks for child_pid

$ ./nerdctl build
FATA[0000] stat /run/user/1000/containerd-rootless/child_pid: no such file or directory
$ ./nerdctl build --buildkit-host /run/user/1000/buildkit/buildkitd.sock
FATA[0000] stat /run/user/1000/containerd-rootless/child_pid: no such file or directory
$ ./nerdctl build --buildkit-host unix:///run/user/1000/buildkit/buildkitd.sock
FATA[0000] stat /run/user/1000/containerd-rootless/child_pid: no such file or directory
$ ./nerdctl build --address unix:///run/user/1000/buildkit/buildkitd.sock
FATA[0000] stat /run/user/1000/containerd-rootless/child_pid: no such file or directory

How do I configure nerdctl to use buildkit OCI instead of containerd

[AkihiroSuda]

nerdctl always requires containerd to be running.

containerd-rootless-setuptool.sh install
containerd-rootless-setuptool.sh install-buildkit

It should be possible to relax this limitation for nerdctl build, but it is not implemented so far.