nerdctl: update to v0.18.0; configure BuildKit with containerd worker

[AkihiroSuda]

BuildKit daemon is now configured to use containerd worker, not OCI worker for efficiency and for supporting using local base images

https://github.com/containerd/nerdctl/blob/v0.18.0/docs/build.md#setting-up-buildkit-with-containerd-worker

[AkihiroSuda]

@ktock PTAL

[ktock]

LGTM

[ktock]

Maybe we should add the following example to the integration test.

https://github.com/containerd/nerdctl/blob/v0.18.0-beta.0/docs/build.md

$ mkdir -p /tmp/ctx && cat <<EOF > /tmp/ctx/Dockerfile
FROM ghcr.io/stargz-containers/ubuntu:20.04-org
RUN echo hello
EOF
$ nerdctl build -t foo /tmp/ctx
$ cat <<EOF > /tmp/ctx/Dockerfile
FROM foo
RUN echo bar
EOF
$ nerdctl build -t bar /tmp/ctx

[AkihiroSuda]

Maybe we should add the following example to the integration test.

https://github.com/containerd/nerdctl/blob/v0.18.0-beta.0/docs/build.md

$ mkdir -p /tmp/ctx && cat <<EOF > /tmp/ctx/Dockerfile
FROM ghcr.io/stargz-containers/ubuntu:20.04-org
RUN echo hello
EOF
$ nerdctl build -t foo /tmp/ctx
$ cat <<EOF > /tmp/ctx/Dockerfile
FROM foo
RUN echo bar
EOF
$ nerdctl build -t bar /tmp/ctx

That should be probably in the nerdctl repo

[ktock]

That should be probably in the nerdctl repo

👍

We already have it in nerdctl repo https://github.com/containerd/nerdctl/blob/10aae5ab75dc8a3156a7853e6cf5da624463bdb9/cmd/nerdctl/build_test.go#L51-L87