Could you elaborate a little more here please?
```
ports:
- "${PORT_PREFIX}01:80"
```
This means that devs can drive the port range that the project bind to by editing their .env file.
However I'd suggest at least specifying a default value so developers don't need to mess with version-controlled .env files to customize their local setups.
That's a good point. Most of my projects tend to ship an `example.env` which documents each env var and introduces a sane default.
When introducing the principle to projects some times a dev will complain about config drift and the like but experience in practice shows that these files tend to change a bit when introduced and then rarely at all so it really is not that much of a deal.