By default, Google Cloud Search indexes all of your G Suite data. You can also create your own custom program, called a connector, to index data stored in a third-party repository. A connector can be a separate program, a script that runs in its own process, or an add-on to your repository.
There are two types of connectors: content connectors and identity connectors. Content connectors are used to traverse a repository and index the data so that Google Cloud Search can effectively search that data.
Identity connectors are used to map your enterprise's identities and group rosters to the Google accounts and groups used by Google Cloud Search. These mappings facilitate setting ACLs and search quality hints during indexing.
Here are a few next steps you might take:
Several connectors have been built by Google and its partners. For a list of pre-built connectors, refer to the Cloud Search connector directory.
For information on how to create a new content connector, refer to Create a content connector.
For information on how to create a new identity connector, refer to Create an identity connector.