Allow building with BuildKit

[schummar]

Adds a withBuildKit option. With the option enabled, a build will be done using BuildKit - within a docker container.
This should be relatively independent on the host system's BuildKit support.

Questions:

• Should the env var DOCKER_BUILDKIT=1 enabled the setting by default?
• Should it be enabled by default in general? For a "just works" for newer dockerfile features like mounts?

Solves #571

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[cristianrgreco]

Hi @schummar, thanks for the contribution!

Because build kit is the default image builder I'd say this should be the default behaviour.

However because this implementation requires a separate container for the build, as well as copying potentially large files between images, I'm concerned about performance, which I assume is significantly worse when compared to a non-buildkit build. If we make this functionality opt-in (keeping withBuildKit), then I'm concerned about maintenance as it's a large and complex change. I haven't run the tests yet but I'm assuming issues with other container runtimes like podman too.

My plan was to wait for build kit to be natively supported by Docker engine and Dockerode, which should result in no or minor changes and no performance impact.

[schummar]

Fair enough. I think the performance might not too bad in comparison. BuildKit builds are usually run in a container anyway, as far as I know - but my knowledge there is admittedly limited. I totally get the reluctance to add the complexity though.

Unfortunately, it's unclear when this might be supported (the referenced issues are 3,5 years old at this point). Usage of BuildKit features is getting more common - my very first try with testcontainers immediately failed because of this 😉. So, it would be good to have some kind of solution. What do you think about these options:

1. I can create a separate npm package that provides the functionality. To load the image some access to container runtime would be great. Like keeping the proposed ImageClient.load method. Or exposing the underlying Dockerode instance?
2. Would you be interested in having that package as a testcontainers module?

[schummar]

@cristianrgreco when you have a minute, could you give feedback?