The Parsoid functionality in RESTbase has been ported into MediaWiki (in core, the Parsoid library, and the Parsoid Extension). Once the ParserCache for Parsoid output has been fully populated (T320534), the Parsoid endpoints in RESTbase should no longer be used.

There are the following cases to cover:

1. The {domain}/v3/page/html endpoint used by internal services. Direct calls to RESTbase should be replaced by access via the service mesh, by assigning a service port for the restbase endpoints. This service port can then be made to point to the parsoid cluster of mediawiki application servers, where the requests are handled by the endpoints exposed by the Parsoid extension.
2. The public /api/rest_v1/page/html endpoint used by external clients. This should be re-routed to the corresponding endpoints exposed by the Parsoid extension. This requires a config change to ATS, either specifically for this prefix, or for all /api/rest_v1/ to go through the API gateway, which can then forward the request to the MediaWiki application servers. see also T334238: Create deprecation plan for public parsoid endpoints and T344946: Create a mechanism for purging output from (parsoid) HTML endpoints from edge caches (without RESTbase).

We should also survey internal services for calls to Parsoid endpoints, and ensure that the above covers all their needs (T333536). They will also need to be changed to make use of the service mesh for accessing the parsoid endpoints.