How do service dependencies work in Docker Compose?

How do service dependencies work in Docker Compose?

In Docker Compose, service dependencies are defined using the 'depends_on' option, which specifies the order in which services should start.

Can you give me an example of how to use 'depends_on'?

Sure! Here's an example: if you have a web service that depends on a database service, you would define it like this:

version: '3'
services:
  web:
    image: my-web-app
    depends_on:
      - db
  db:
    image: postgres

Does 'depends_on' wait for the service to be ready?

No, 'depends_on' only ensures that the dependent service starts before the service that depends on it. It doesn't wait for the service to be fully ready.

How can I ensure a service is fully ready before starting another?

You can implement health checks in your services and use a script to wait for the service to be healthy before starting the dependent service.