API push source
The API push source is a source configuration to create and maintain indexes exclusively for content you push to Sitecore Search. After you configure an API push source, a developer uses the Ingestion API to add documents to the API push source's index.
For example, assume that your content is on a social networking-type site that consists exclusively of visitor-generated content. Visitors create, update, and delete content every few seconds. To ensure that the latest content is always searchable, you can create an API push source and, in your application, have a developer set up a webhook that calls the Ingestion API every time content is created, updated, or deleted.
Available locales for an API push source
When you configure an API push source, there is only one setting to consider, and it is optional: the locales available to this source. By default, Search adds the first locale defined in the Administration > Domain Settings > Locale section of the CEC. You'll need to add the other locales.