nix2container-image-info.yaml

apiVersion: tekton.dev/v1beta1
kind: Task
metadata:
  name: nix2container-image-info
  labels:
    app.kubernetes.io/versions: "0.1"
spec:
  description: >
    Get the image name and tag from a nix2container flake output.
  workspaces:
    - name: optional-src
      optional: true
      description: |
        The source repository to invoke from.
      mountPath: /mnt
      readOnly: true
    - name: nix-store
      description: |
        An workspace containing a nix store. Appended via a `--store` argument.
      readOnly: true
      mountPath: /workspace/nix-store/nix
  params:
    - name: flakeOutput
      type: string
      description: |
        The output of a Nix Flake. This output must refer to an image built with
        nix2container.

        See:
          - https://nixos.wiki/wiki/Flakes for more in formation on the Flake
            URL schema.
          - https://github.com/nlewo/nix2container for more information on the
            required builder for the flake outputs.

        Examples:
          - "/mnt/src_root#someoutput" for a flake output in the `output-src`
            directory.
          - "github:TraceMachina/nativelink#image" for the latest nativelink
            image.
          - "github:<user>/<repo>?ref=pull/<PR_NUMBER>/head#<PACKAGE>" to use
            an image from a pull request of a repository on GitHub.
  results:
    - name: imageName
      description: The Nix-derived image name.
    - name: imageTag
      description: The Nix-derived image tag.
  steps:
    - name: get-image-tags
      image: nixpkgs/nix-flakes:latest
      env:
        - name: FLAKE_OUTPUT
          value: "$(params.flakeOutput)"
      script: |
        #!/usr/bin/env sh

        if [ "$(workspaces.optional-src.bound)" = "true" ]; then
          cd "$(workspaces.optional-src.path)"
        fi

        if [ "$(uname -m)" = "x86_64" ] && [ "$(uname -s)" = "Linux" ]; then
          NIX_SOCKET="unix:///workspace/nix-store/nix/var/nix/daemon-socket/socket"
          NIX_ROOT="/workspace/nix-store"
          NIX_STORE_OPTS="--store ${NIX_SOCKET}?root=${NIX_ROOT}"
        else
          NIX_STORE_OPTS=""
        fi

        echo "NIX_STORE_OPTS: '$NIX_STORE_OPTS'"

        # Not ideal, but will have to do until we implement more elaborate git
        # repo syncing schemes.
        git config --global --add safe.directory "*"

        IMAGE_NAME=$(nix eval $NIX_STORE_OPTS "${FLAKE_OUTPUT}".imageName --raw)
        IMAGE_TAG=$(nix eval $NIX_STORE_OPTS "${FLAKE_OUTPUT}".imageTag --raw)

        echo "Evaluated IMAGE_NAME: '$IMAGE_NAME'"
        echo "Evaluated IMAGE_TAG: '$IMAGE_TAG'"

        echo -n "${IMAGE_NAME}" > $(results.imageName.path)
        echo -n "${IMAGE_TAG}" > $(results.imageTag.path)