docker buildx bake and variables

[elangelo]

I have a Dockerfile that defines multiple targets that i can build.

so I created a docker-bake.hcl:

variable "IMAGES" { 
  default = [ "foo", "bar" ]
}
variable "TAG" {
  default = "dev"
}
target "dev-env" {
  name = ${tgt}
  tags = "${tgt}:${TAG}"
  context = "."
  dockerfile = "Dockerfile"
  matrix = {
    tgt = IMAGES
  }
}

imagine the Dockerfile looks something like this:

FROM python:3.11-slim-bookworm AS base

FROM base AS foo
FROM base AS bar
FROM base AS dev

This works like a charm.

Though I'm struggling to override the IMAGES from the commandline
Imagine I also want to build the dev target

IMAGES="[foo,bar,dev]" docker buildx bake dev-env

results in:

docker-bake.hcl:1
--------------------
   1 | >>> variable "IMAGES" { 
   2 |       default = [ "foo", "bar" ]
   3 |     }
--------------------
ERROR: docker-bake.hcl:1,19-19: Invalid value; unsupported type tuple for variable IMAGES