Starting 2 services at the same time

I have 2 services say A and B. The service A depends on B to start and B depends on A. I want to start them both at the same time. How do I do it?

you can define your services in the services section [1], which starts containers in parallel

- name: redis
  image: redis

- name: mysql
  image: mysql


Thanks for the help. I also wanted to know how to start cockroachDB in Drone CI