How can I know when Kestrel has started listening?

Question

I need to notify systemd that my service has started up successfully, and a task it needs to run after startup requires that the server is already listening

Answer 1

You may use Microsoft.AspNetCore.Hosting.IApplicationLifetime:

/// 

/// Triggered when the application host has fully started and is about to wait
/// for a graceful shutdown.
/// 
CancellationToken ApplicationStarted { get; }

Look into this SO post for the configuration example.