# 3. Config add devices

Blueapi is highly configurable. The config details aspects that impact how Blueapi works and it is customisable. 

As a first step, create a `config.yaml` file. This would be best placed in the `docs/resources` folder. 

Initially, add devices using the following code:

```yaml
env:
  metadata:
    instrument: demo
  sources:
    - kind: deviceManager
      module: blueapi.tutorial.devices
```

The `env` section of the `config.yaml` file lets you create and set environment variables. The `demo` points to optional dependencies in the [pyproject.toml file](../../pyproject.toml). The module above points to the devices you will use for this tutorial which can be found [here](../../src/blueapi/tutorial/devices.py).

Save the file and restart the worker to use this new `config.yaml` file you have created. To do this, navigate back to the terminal window where the worker is running, CTRL+C to close it then run the following command: 
``` 
blueapi --config docs/resources/config.yaml serve 
```

The above command assumes you created the `config.yaml` file in `docs/resources`. Else, replace `docs/resources/config.yaml` with whichever file path your `config.yaml` has.

Now run 
```blueapi controller devices``` in the same terminal window as you did when previously running this command and you should see `det` and `stage`.