I'm trying to build a container image using

pulumi_docker.Image

, passing

"DOCKER_BUILDKIT": "1"

in the

pulumi_docker.DockerBuild

env

argument, as documented (https://www.pulumi.com/docs/reference/pkg/docker/image/#dockerbuild) to enable BuildKit support, but my image builds are failing with errors like

error: the --mount option requires BuildKit. Refer to <https://docs.docker.com/go/buildkit/> to learn how to build images with BuildKit enabled

which suggests that BuildKit somehow isn't being used. Has anyone else been successful with a BuildKit-enabled image build?