buildx/docs/guides/cni-networking.md

CNI networking

It can be useful to use a bridge network for your builder if for example you encounter a network port contention during multiple builds. If you're using the BuildKit image, CNI is not yet available in it, but you can create a custom BuildKit image with CNI support.

Now build this image:

$ docker buildx build --tag buildkit-cni:local --load .

Then create a docker-container builder that will use this image:

$ docker buildx create --use \
  --name mybuilder \
  --driver docker-container \
  --driver-opt "image=buildkit-cni:local" \
  --buildkitd-flags "--oci-worker-net=cni"