nix-gitlab-ci/templates/nix-gitlab-ci.yml

spec:
  inputs:
    image_tag:
      type: string
      description: "latest | latest-cachix | latest-attic etc."
      default: latest
    cache_files:
      type: array
      description: |
        Files to use as the cache key for the generated pipeline yaml.
        If you use "ci.nix" to define CI, add that here for example
      default: ["flake.nix", "flake.lock"]
    disable_cache:
      type: string
      description: |
        Disables any caching provided by this component. Set to any non-empty value to disable caching.
      default: ""
---
stages:
  - build
  - trigger
variables:
  NIX_CI_DISABLE_CACHE: "$[[ inputs.disable_cache ]]${NIX_CI_DISABLE_CACHE:-}"
nix-ci:build:
  stage: build
  image: registry.gitlab.com/technofab/nix-gitlab-ci/nix-ci:$[[ inputs.image_tag ]]
  cache:
    - key:
        files: $[[ inputs.cache_files ]]
      paths:
        - generated-gitlab-ci.yml
    - key: nix
      paths:
        - .nix-cache/
  before_script:
    # generated-gitlab-ci.yml exists in the cache
    - '[ -f "generated-gitlab-ci.yml" ] && export CACHED=true && echo "Using cached pipeline file (skip cache with NIX_CI_SKIP_CACHE)" || true'
    # allow the user to manually skip the cache (when the key files are not correctly configured etc.)
    - '[ -n "$NIX_CI_SKIP_CACHE" ] && unset CACHED && echo "Caching skipped for this job (through NIX_CI_SKIP_CACHE)" || true'
    # only setup when we need to generate the pipeline yaml
    - 'if [ -z "$CACHED" ]; then source setup_nix_ci; fi'
  script:
    # build the generated-gitlab-ci.yml if it does not exist in the cache
    - 'if [ -z "$CACHED" ]; then nix build .#gitlab-ci-config && install result generated-gitlab-ci.yml; fi'
  after_script:
    # NOTE: environment variables of before_script and script don't exist here anymore
    #
    # save to binary cache or Gitlab CI cache only if we actually built something
    #  check if /tmp/nix-store-before exists as $CACHED never exists here and the file only exists if "setup_nix_ci" is called
    - 'if [ -f "/tmp/nix-store-before" ]; then finalize_nix_ci; fi'
  artifacts:
    paths:
      - generated-gitlab-ci.yml
nix-ci:trigger:
  stage: trigger
  needs:
    - nix-ci:build
  trigger:
    include:
      - artifact: generated-gitlab-ci.yml
        job: nix-ci:build
    strategy: depend
    forward:
      pipeline_variables: true