docker-compose - env vars based on the ports

Question

So I have 2 services running - my website and the API.

In my code for the website I specified that it should use the API that has port equal to API_PORT env var.

My question: is there a way to set the API_PORT variables based on the ports from api service?

Overview of my docker-compose.yml :

api-service:
    ...otherconfig
    ports:
      - 8009:8009
website:
    ...

Answer 1

Just inject the API_PORT env var into your compose file too:

export API_PORT=8009

then in the compose file

api-service:
    ...otherconfig
    ports:
      - ${API_PORT}:${API_PORT}
website:
    ...