Script Functions

Grog injects a couple of helper shell functions into every target command and output check. These helpers let you reference dependency outputs without hard-coding file paths or worrying about where the target is executed from.

$(bin)

$(bin //pkg:target) returns the absolute path to the dependency’s bin_output. You can also use the shorthand $(bin :target) for dependencies that live in the same package, or $(bin //pkg) when the target label can be shortened.

YAML

- name: generate_stubs
  dependencies:
    - //tools:protoc
  command: |
    # The protoc binary path resolves automatically regardless of cwd
    $(bin //tools:protoc) --python_out=generated proto/*.proto
  outputs:
    - dir::generated

Pkl

targets {
  new {
    name = "generate_stubs"
    dependencies {
      "//tools:protoc"
    }
    command = """
    # The protoc binary path resolves automatically regardless of cwd
    $(bin //tools:protoc) --python_out=generated proto/*.proto
    """
    outputs {
      "dir::generated"
    }
  }
}

$(output)

$(output <label> <index>) exposes every output produced by a dependency. Indexes are zero-based and follow the order defined in the dependency’s outputs list (with its bin_output appended last when present). File and directory outputs resolve to absolute paths on disk, while other output types return their identifier strings—for example, Docker outputs return the image tag you defined.

YAML

- name: package_site
  dependencies:
    - //frontend:build
  command: |
    # Copy the compiled assets from the build target's first output directory
    cp -R $(output //frontend:build 0) dist/
  outputs:
    - dir::dist

Pkl

targets {
  new {
    name = "package_site"
    dependencies {
      "//frontend:build"
    }
    command = """
    # Copy the compiled assets from the build target's first output directory
    cp -R $(output //frontend:build 0) dist/
    """
    outputs {
      "dir::dist"
    }
  }
}

Use the same shorthand label forms as $(bin) (:target for same-package deps and //pkg for shorten-able labels). If you reference an index that does not exist—or a dependency that produces no outputs—Grog exits with an error so you can fix the command quickly.

To reference Docker images (or any other non-filesystem outputs), use the identifier directly:

YAML

- name: smoke_test_image
  dependencies:
    - //containers:backend_image
  command: |
    docker run --rm $(output //containers:backend_image 0) --health-check

Pkl

targets {
  new {
    name = "smoke_test_image"
    dependencies {
      "//containers:backend_image"
    }
    command = """
    docker run --rm $(output //containers:backend_image 0)
    """
  }
}