matrix-spec-proposals/proposals/2320-identity-versions.md

Versions information for identity servers

The client-server API currently specifies a /versions endpoint that allows clients to know what version of that API are implemented by the server. Identity servers could benefit from that endpoint as both homeservers and clients interact with them, and therefore could know which features they can expect a given identity server to implement by looking at the versions of the API it claims to support.

Proposal

This proposal adds the following endpoint to the identity server API.

GET /_matrix/identity/versions

This endpoint serves information about the versions of the identity server API this identity server supports. Its response uses the following format:

{
    "versions": [
        "r0.1.0",
        "r0.2.0",
        "r0.2.1",
    ]
}

Alternative solutions

Another solution which was considered was using the status check endpoint (GET /_matrix/api/v1) to serve this information. This solution was discarded because it's using a versioned endpoint, which doesn't make sense to advertise the supported versions of the API to use.