This endpoint logs the specified customer into Antavo and a successful login returns the customer object.

The username attribute can be specified in the Antavo Management UI from any available profile attribute.
The customer ID can then be accessed and used for subsequent calls using Antavo Display API endpoints.

A successful log-in will also create a daily_login event for the customer.
This event will only be written once to the customer's event stream per calendar day.

This requires the Custom login module to be enabled.