Shared secret authorization with Azure SignalR Service

While testing out Azure Functions development and configuration with Azure SignalR Service, I needed a very simple key-based (shared secret) authorization mechanism so that my console-based SignalR client could connect to my Azure SignalR Service-powered hub using a very simple mechanism.

The docs and the sample showcased the negotiate endpoint returning the connection info directly:

[FunctionName("negotiate")]
public SignalRConnectionInfo Negotiate([HttpTrigger(AuthorizationLevel.Anonymous)]HttpRequest req)

But a stackoverflow answer pointed me to the solution: just the proper IActionResult using OkObjectResult with the connection info when the access key is properly validated:

[FunctionName("negotiate")]
public IActionResult Negotiate(
[HttpTrigger(AuthorizationLevel.Anonymous, "post")] HttpRequest req,
[SignalRConnectionInfo(HubName = "events")] SignalRConnectionInfo connectionInfo)
{
var expectedKey = Environment.GetEnvironmentVariable("AccessKey");
if (string.IsNullOrEmpty(expectedKey))
return new OkObjectResult(connectionInfo);
var accessKey = req.Query["accessKey"];
if (StringValues.IsNullOrEmpty(accessKey) ||
!StringValues.Equals(expectedKey, accessKey))
return new UnauthorizedResult();
return new OkObjectResult(connectionInfo);
}