Context.UserIdentifier is null after switching to Azure SignalR Service - azure

Question

My SignalR Hub requires users to be authenticated and the following line gives me user's Id:
var userId = Context.UserIdentifier;
Similarly, I can get the whole set of claims with:
var user = Context.User.Claims;
This works fine if I use SignalR locally but if I switch to Azure SignalR Service, I get a null value in Context.UserIdentifier. I also get no claims.
Here's what I'm changing in my Startup.cs:
In the ConfigureServices() method, I use
services.AddSignalR().AddAzureSignalR(Configuration["AzureSignalR:ConnectionString"]);
instead of
services.AddSignalR();
And in the Configure() method, I use:
app.UseAzureSignalR(routes =>
{
routes.MapHub<Hubs.MyHub>("/chat");
});
instead of:
app.UseSignalR(routes =>
{
routes.MapHub<Hubs.MyHub>("/chat");
});
Do I need anything else in Azure SignalR configuration to make sure I get user's claims? Any idea why this one change prevents claims from coming through?
P.S. I'm using Azure AD B2C for user authentication and as I said, if I use SignalR locally, everything works which means the code that handles grabbing JWT token from QueryString is working fine.

Answer 1

SignalR service will automatically inherit the claims from your authenticated user, no special configuration is needed. I just tried Azure AD B2C sample with SignalR service and the claims can be get from HubCallerContext.
Could you please check the SignalR access token returned from negotiation to see whether the claims are returned from server at the first place? (Decode it from base64 then you'll see the claims)