Drone CI with nodejs, npm and private modules

.drone.yml

# drone.yml for node js CI with npm login
# Don't forget to configure DRONE_SERVER and DRONE_SERVER
# Now create a secrets.yml (OUTSIDE of your repo!!) (see other file)
# then run drone secure --repo <drone_repo_name> --in <path>/secrets.yml
build:
  unit_tests:
    image: risingstack/alpine:3.3-v4.2.6-1.1.3
    commands:
      - npm config set //registry.npmjs.org/:_authToken=$NPM_TOKEN
      - npm install
      - npm run build
      - npm run test
    # the environment is transient so cleanup isn't really necessary
    environment:
      - NPM_TOKEN="$$NPM_TOKEN"

cache:
  mount:
    - node_modules

secrets.yml

# set this to npm token in ~/.npmrc, can be revoked via npmjs.com later
# Do not commit this to any repo (duh)
environment:
  NPM_TOKEN: <npm_token>