when using

docker_image

I was a bit surprised that I couldn't access a

Dockerfile

outside of the

BUILD

directory or children. It makes sense with how Pants works in general, but if you compare to Python where source files are a first-class target, it's a bit different. Would it make sense to have a

dockerfile_source

target that can get referenced in the

docker_image

source

field, which I believe would allow for the kind of access I was looking for?

What do you mean with "access"? Use in a

source

field? If so, you can't do that with python sources either.. You can't reference other targets in the

source

field, so a

dockerfile_source

target wouldn't help. I guess you might've thought of using the

dependencies

field for this, which would work, but the better approach is to simply move your

docker_image

target up in the source tree instead, as the location of the

Dockerfile

affects the scope of your docker build context, there's a can of worms lurking if we support pointing to them arbitrarily.

yeah I meant using the

dependencies

field on `docker_image`to point at a target created with

dockerfile_source

. So something like this:

/docker/service/Dockerfile
/docker/service/BUILD <- has `dockerfile_source(name="image", source="Dockerfile")
/service-a/BUILD <- has `docker_image(dependencies=["//docker/service:image", ":bin"])`
/service-b/BUILD <- same docker_image, different `:bin` target

but yeah, I'm somewhat unaware of the problems that may cause. Maybe it wouldn't work.

A couple of ideas for potential consideration: Unless you need the

Dockerfile

on disk, you can put the contents in a macro file:

# prelude.py
DOCKER_INSTRUCTIONS = """
FROM foo
COPY bar baz
...
""".split("\n")

then in any BUILD file:

# /service-a/BUILD
docker_image(instructions=DOCKER_INSTRUCTIONS, ...)

that way you can share the same Dockerfile instructions between multiple docker image targets in different parts of the repo. The other option is to share a common base image, and get a "kind of" multi stage build:

# /docker/service/BUILD
docker_image(name="common", ...)

# /service-a/Dockerfile
ARG base=docker/service:common
FROM $base
COPY svc-a /specifics/

Pants will pick up on your dependency to the common base image, and build it first, then build service-a image where the common base image will be used in the FROM instruction..

those are good suggestions, thanks!