What is the difference between oci workers and containerd workers?

[vlad-ivanov-name]

If I create a builder as follows:

docker buildx create --name buildx-default --driver docker-container --bootstrap

I can see the following in the logs of the container created:

found worker \"...\", labels=map[org.mobyproject.buildkit.worker.executor:oci ...
skipping containerd worker, as \"/run/containerd/containerd.sock\" does not exist

What are oci workers and containerd workers? What responsibilities do they have and will choosing one over another provide any benefits?

I'm particularly interested whether choosing containerd worker will speed up loading images into docker (see docker/buildx#107 )

[tonistiigi]

The difference is in whether BuildKit will use its own storage dir for layer blobs and snapshots or reuse the one containerd instance already manages. If you use buildx create your only option is the OCI driver. Using containerd worker does not speed up loading images into docker atm, it does speed up loading images into containerd.

[vlad-ivanov-name]

Thank you!