Is there any way to add some kind of template for the

instructions

field of

docker_image

and then reuse it for multiple applications? E.g.

instructions=[
    "FROM python:${VARIANT}"
    "COPY ${DYNAMIC_DIR} /app",
  ]

Background: the Dockerfile for a lot of services looks almost the same.

We use a macro: https://www.pantsbuild.org/docs/macros

You could use macros for that, or if on bleeding edge, the new

__defaults__

feature: https://www.pantsbuild.org/docs/macros https://github.com/pantsbuild/pants/blob/main/docs/markdown/Using%20Pants/concepts/targets.md#field-default-values

Although, personally, macros aren't my favorite for some things because they ar eopt-in which means devs have to know to use them.

__defaults__

is another angle. Also if the targets are in the same

BUILD

, remember

BUILD

files are just Python(-ish)

It’s Python, not ish, just that they’re sandboxed that makes them a bit like ish. 😉

Using a template is great, though. John showed me https://pex.readthedocs.io/en/latest/recipes.html?highlight=container#pex-app-in-a-container which speeds up container startup. Fixed all of our containers with one change

Oh, the distinction 🙈

Okay, so for the macro I can see from the docs that "A macro can take new parameters to generate the target dynamically", which should work in that case. But I am not getting how the

__defaults__

feature can be utilized here. Can you give an example?

So using a macro would be completely separate from using the defaults target. When I'm on my desktop I can whip up an example

I am not getting how the

__defaults__

feature can be utilized here. Can you give an example?

Ah, I somehow overlooked the dynamic nature of the default template you asked for @thousands-plumber-33255. So

__defaults__

would not be a fit for that case.