# Profiles for Optional Services — Docker Compose

Source: https://www.skillbyai.com/en/docker-compose/e-profiles

> Start extra tools only when asked.

## profiles: and --profile

Services with a `profiles` list start only when one of those profiles is active (`--profile debug` or `COMPOSE_PROFILES=debug`). Services without profiles always start. Use profiles for optional tools: database admin UIs, mail catchers, load generators, test runners. This keeps the default `up` lean while making extras one flag away.

## Services with and without a profile, run

I ran this with Docker Compose v2.38.1 and jq in the demo "shop" project. docker compose config parses, interpolates, merges and validates the files without starting containers; the Docker daemon was not running, so nothing was started. By default the project has db, api and web; activating the debug profile adds the adminer database UI.

```bash
docker compose config --services
echo "--- with the debug profile:"
docker compose --profile debug config --services
```

Output:

```
db
api
web
--- with the debug profile:
adminer
db
api
web
```

## Document your profiles

List available profiles and what they add in the README so new developers find them.

**Quiz:** When does a service with profiles: ["debug"] start?

- [ ] Only in production
- [ ] Always
- [ ] Never
- [x] Only when the debug profile is activated

*Answer:* Only when the debug profile is activated. Profiles make services optional.