Background We sometimes want to get the current number of DPs and specific information about each DP on the Admin API. Currently, we have the server-info plugin that can report the information of that DP on the DP.
Solution Move server-info from a separate plugin into the main code. To reduce the impact on users who have server-info explicitly enabled, we keep server-info as a plugin, but it's just an empty shell that prints a Warning log. In the Admin API, we add the GET /apisix/admin/data_planes interface to support getting information about a single data_plane or all data_planes. In documentation, we add a new document "DP Information Reporting", which describes how DP reports information.
