How to access platform as a build-arg?

[educlos]

Hello,
I'm checking this action to build one of our docker image, but I'm wondering how I could get the platform as a build-arg
It looks like this:

      - name: Build and push
        id: build-docker
        uses: docker/build-push-action@v6
        with:
          file: Dockerfile-base
          platforms: linux/amd64,linux/arm64
          no-cache: true
          build-args: |
            PHP_VERSION=${{ matrix.version }}
            TARGET_PLATFORM=${{ not sure what to put here }}
          push: true

I know I could get it by using a matrix. build each platform on its own and then build the manifest (which is what I'm currently doing, just without this action), but from what I understand this action does all that, so if I could use it it would make the action shorter.

[educlos]

I ended up modifying my Dockerfile to not need the TARGET_PLATFORM anymore, so I'll close this one

[crazy-max]

You can use the built-in arg named TARGETPLATFORM so you don't need to pass anything: https://docs.docker.com/reference/dockerfile/#automatic-platform-args-in-the-global-scope