RUN --mount=type=bind doesn't work

[shollander]

Expected Behavior

Use RUN --mount=type=bind to install dependencies in efficient manner. e.g. Dockerfile:

FROM python:3.12-slim
RUN --mount=type=bind,source=myapp,target=/tmp/myapp pip install /tmp/myapp

Current Behavior

Fails with the following error:

Could not build image: the --mount option requires BuildKit. Refer to https://doc.docker.com/go/buildkit ro learn how to build images with BuildKit enabled

Context

This Dockerfile works fine with command line docker build .

[bmuschko]

The Docker remote API does not support buildkit as of now.

[shollander]

I'm not sure what you mean by that. According to the Docker documentation, it appears that the remove driver does support BuildKit.

[bmuschko]

We are not using the Docker executable with this plugin. We are using the RESTful API.

[shollander]

It looks to me like the RESTful API does support BuildKit.

The imageBuild API has a parameter called version that should be set to 2 to use BuildKit.

[bmuschko]

OK, seems like Docker added that to the API recently. Unfortunately, Docker Java, the wrapper around the Docker API, does not support it yet: docker-java/docker-java#2362