1. Set your system Application Default credentials:

gcloud auth application-default login

https://cloud.google.com/sdk/gcloud/reference/auth/application-default/login

2. Example integration into your package.json

{
  "name": "test-scripts",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "config-edit": "parsley-scripts config edit",
    "config-install": "parsley-scripts config install",
    "config-install-yaml": "parsley-scripts config install-yaml",
    "prune-versions": "parsley-scripts prune --minVersions=5",
    "deployment-copy": "parsley-scripts deployment copy"
  },
  "author": "",
  "license": "ISC",
  "parsley-scripts": {
    "profiles": {
      "default": {
        "project-id": "parsley-project-1",
        "deployment-file-name": "app.yaml",
        "service-name": "foo-bar"
      },
      "parsley-project-1": {
        "project-id": "parsley-project-1",
        "deployment-file-name": "app.yaml",
        "service-name": "foo-bar"
      }
    }
  }
}