We go over a mistake I made when using Docker volumes! I didn't assign a volume to the two services (mysql database, redis cache) that need to use the volumes we tell Docker Compose to create!

version: '3'
services:
  cache:
    image: redis:alpine
    networks:
     - appnet
    volumes:
     - cachedata:/data
  db:
    image: mysql:5.7
    environment:
      MYSQL_ROOT_PASSWORD: secret
      MYSQL_DATABASE: homestead
      MYSQL_USER: homestead
      MYSQL_PASSWORD: secret
    networks:
     - appnet
    volumes:
     - dbdata:/var/lib/mysql
networks:
  appnet:
    driver: bridge
volumes:
  dbdata:
    driver: local
  cachedata:
    driver: local

Here we added the volumes: section to the cache and db services.