TIL: YAML's special indicators > and | handle of multiline strings

| means "literal block scalar", which produces a multiline string with no special formatting

run:
  command: |
    npm run dev
    npm run test

translates to:

npm run dev\nnpm run test

The cool one I learned about today is >-, a "folded block scalar". It preserves line breaks as spaces (folding them into a single line). The - modifier tells YAML to "chomp" (remove) any trailing newlines at the end of the block.

Example YAML

services:
  postgres:
    image: postgres
    restart: always
    options: >-
      --health-cmd pg_isready
      --health-interval 10s
      --health-timeout 5s
      --health-retries 5

translates to

... --health-cmd pg_isready --health-interval 10s --health-timeout 5s --health-retries 5