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

This is what I did to overcome the issue.

1- I registered ApplicationStopped event. So that it brute force terminates the app by calling Kill() method of the current process.

public void Configure(IHostApplicationLifetime appLifetime) {
 appLifetime.ApplicationStarted.Register(() => {
  Console.WriteLine("Press Ctrl+C to shut down.");
 });

 appLifetime.ApplicationStopped.Register(() => {
  Console.WriteLine("Terminating application...");
  System.Diagnostics.Process.GetCurrentProcess().Kill();
 });
}

See IHostApplicationLifetime docs

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2- Don't forget to use the UseConsoleLifetime() while building the host.

Host.CreateDefaultBuilder(args).UseConsoleLifetime(opts => opts.SuppressStatusMessages = true);

See useconsolelifetime docs