> ## Documentation Index
> Fetch the complete documentation index at: https://docs.domino.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Custom authentication

The TrainingSetClient is a Python module wrapping a set of API methods. See [Authentication](/cloud/reference/api/data_api/authentication) for the default behavior of the TrainingSetClient.

To override authentication, you need to set the right environment variable with your own user API key:

```python theme={null}
import os

os.environ["DOMINO_USER_API_KEY"] = "<your-own-api-key>"

# In Domino endpoint if the client version is <0.1.8
os.environ["DOMINO_API_HOST"] = os.getenv("DOMINO_USER_HOST")
```

```shell theme={null}
export DOMINO_USER_API_KEY=<your-own-api-key>

# In Domino endpoint if the client version is <0.1.8
export DOMINO_API_HOST=$DOMINO_USER_HOST
```