App Service Graceful Shutdown / Migrate Connections help

Framework: .net5.0 Microsoft.Azure.SignalR: v1.8.0

I have an Azure App Service which I am using as the “Hub Server” in “Default Mode” and I deploy to a staging slot on the service to then swap in the new version.

I have found the documentation on Graceful Shutdown and also read the settings documentation around GracefulShutdown.Mode.

My deployment Pipeline deploys the new version to the staging slot then swaps it in to the production. At this point my clients may be “connected” (proxied through the Azure SignalR service) to the old version in the staging slot.

I’ve configured, as per the documentation, the Graceful Shutdown to Migrate the connections over:

options.GracefulShutdown.Mode = GracefulShutdownMode.MigrateClients;
options.GracefulShutdown.Timeout = TimeSpan.FromSeconds(90);
options.GracefulShutdown.Add<Hubs.NotificationHub>(c =>
{
    Trace.WriteLine("GRACEFUL SHUTDOWN");
    return c.Clients.All.SendAsync("GracefulShutdown");
});

And after the swap my Pipeline stops the staging slot.

But from what I can see - there is no migration, or even graceful shutdown - the client connections get disconnected immediately and reconnect (sometimes the Disconnect is actually logged after the Reconnect, but this is a side issue).

Is there something I am doing wrong? Is this the correct approach?

If I don’t shut down the staging slot then clients remain connected to the old version in the staging slot and new clients can even connect to it. In the documentation it talks about “Set the Server Offline” - but it isn’t clear about the approach for this. Should I be adding a sticky slot setting to do this - something like removing the Azure SignalR connection string? But as I understand on the swap, this would cause a settings change and an application reload therefore terminating the connections anyway?

Could someone give me some guidance on this? Firstly why I see no appearance of the Graceful Shutdown, and then any advice on the recommended way to do this?

[terencefan]

I’ll see if it works well, sorry for any inconvenience.

[terencefan]

https://github.com/Azure/azure-signalr/pull/1376 The bug is fixed in 1.10.0. It was broke by one of our latest changes that allowed the application task to stand alone for a while after the connection has been closed.