Extension-based authentication

Some authentication mechanisms, such as basicauth, oauth2client, and sigv4auth, are OpenTelemetry extensions that the exporter references by using auth.authenticator. You must define the extension before the exporter that uses it.

Supported extensions:

Basicauth
Bearertokenauth
Sigv4auth
Spnegoauth

Configure an authenticator extension by running the following commands:

Add the extension ./obs-cli.sh add-extension --file extension.yaml
YAML file (extension.yaml):
```
basicauth/partner:
  client_auth:
    username: [***USERNAME***]
    password: [***PASSWORD***]
```

Reference it from your exporter in exporter.yaml:

prometheusremotewrite/partner:
  endpoint: "https://receive.example.com/api/v1/receive"
  auth:
    authenticator: basicauth/partner

You must export and verify. To export and verify, see the Exporting and verifying documentation.