How do I manage dependencies in Docker Compose?

How do I manage dependencies in Docker Compose?

In Docker Compose, you can manage dependencies using the depends_on option in your docker-compose.yml file.

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

Sure! Here's a simple example:

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

This ensures that the db service starts before the web service.

Does depends_on wait for the service to be ready?

No, depends_on only ensures that the service starts. It doesn't wait for it to be fully ready. You might need to implement health checks for that.

What are health checks and how do I implement them?

Health checks are used to determine if a service is running correctly. You can implement them in your docker-compose.yml like this:

services:
  db:
    image: postgres
    healthcheck:
      test: ['CMD', 'pg_isready']
      interval: 30s
      timeout: 10s
      retries: 5