How components should reach each other?

How components inside Digital Ocean Apps platform should reach each other via network? For example, I have 2 components, one is worker, another one is plain nginx with proxy_pass configuration to worker. I am referring to service names while using docker compose. What should I use here?

Docker compose file:

version: "3"
services:
  tileserver:
    build: .
  frontend:
    build: frontend
    ports:
      - "8080:80"
    depends_on:
      - tileserver

Inside frontend there is nginx.conf file with the following:

...
            proxy_pass http://tileserver;

...

Here is how it looks for my digital ocean apps platform spec:

name: maps
region: ams
services:
- dockerfile_path: frontend/Dockerfile
  source_dir: frontend/
  github:
    branch: m/mbtiles
    deploy_on_push: true
    repo: digitaz/maps
  http_port: 80
  instance_count: 1
  instance_size_slug: basic-xxs
  name: frontend
  routes:
  - path: /
workers:
- dockerfile_path: Dockerfile
  github:
    branch: m/mbtiles
    deploy_on_push: true
    repo: digitaz/maps
  instance_count: 1
  instance_size_slug: basic-xxs
  name: tileserver

How containers tileserver and frontend should reach each other? Specifically, how frontend should reach tileserver?