Run Redis with persistent storage using docker-compose

Question

How do I tell CircleCI and docker-compose to run Redis with persistent storage? I expected to see something like docker run -d -p 6379:6379--name redis dockerfile/redis in circle.yml where I can add a -v <data-dir>:/data to, but I only see redis listed under services: in circle.yml:

machine:
  services:
    - redis
  node:
    version: 6.3.0
  python:
    version: 3.5.2

# ...deployment commands follow, but no redis