authenticate socket.io connection

[developer-diganta]

I am currently building a chat-app that has a separate auth server that uses keycloak and passport for user validation and authorisation. After the login is complete, I get a session id. After this I am trying to establish a socket connection with the backend server (separate from auth). But I am unable to do so. Here are the problems:

1. I am not able to validate since the passport instance is separate (auth is a completely different server)
2. If I send only the user_id to make a connection, I believe it won't at all be secure.
   Also, I cannot do direct socket connection, since I am using socket only to send messsages from backend to frontend, the other request is done using api (i.e. from frontend to backend).
   I checked this discussion : How to get authenticated user details in socket.io with passport.js ? Why user is undefined in socket.request.user ? #4470 but this did not solve the issue.