[[Docker-in-docker]]

**Re-usable scripts** via YAML anchors, `extends` doesn't seem to merge scripts.
```
.devstack-script: &devstack-script
  - echo "${SECURE_YAML}" > secure.yaml
  - echo "${SSH_PRIVATE_KEY}" | base64 -d > ssh-id

blaat:
  script:
    - *devstack-script
    - myscript
```