Context & Description

When scaling the number of processes by setting the publicAddress config in the server, the client will not be able to connect to the server from within the sandboxed Discord Activity due to CSP:

This problem occurs because the Colyseus SDK will use the publicAddress configured in the server to establish the WebSocket connection, whereas the Discord Activities require every request to go through their sandboxed relative URLs where URL Mappings can be set for external services.

Proposed API

The client-side SDK should be able to customize the endpoint URL before trying to establish the connection. We could expose an API that is capable of customizing the output of buildEndpoint()