In **docker-compose.yml** file:

```yaml
version: "3.7"

services:
  backend:
    ...
    ports:
      - "8000:8000"
    expose:
      - "8000"
    networks:
      - dev

  frontend:
    ...
    ports:
      - "3000:3000"
    networks:
      - dev


networks:
  dev:
    driver: bridge
```

Since both `backend` and `frontend` containers are on the same network, you can now access `localhost:8000` from the `frontend` container.

Use Docker networks to share the same localhost between containers.