build.yml

---
  platform: linux
  image_resource:
    type: docker-image
    source:
      repository: {{registry-repo-url}}
      username: {{registry-username}}
      password: {{registry-password}}
      email: {{registry-email}}
      tag: 'latest'

  inputs:
  - name: app-repository
    path: /go/src/github.com/example/app

  run:
    dir: /
    path: sh
    args:
      - -exc
      - |
        ls

pipeline.yml

resources:
  - name: app-repository
    type: git
    source:
      uri: git@github.com:example/app.git
      branch: master
      private_key: {{git-private-key}}
      
jobs:

  - name: build
    plan:
      - do:
        - get: app-repository
          trigger: true

        - task: build
          file: app-repository/scripts/ci/build/build.yml