ApplicationShutdownExtensionMethods.cs

using System;
using System.Threading.Tasks;
using Microsoft.Framework.Runtime;
using Mono.Unix;

public static class ApplicationShutdownExtensionMethods
{
    public static void OnUnixSignals(this IApplicationShutdown applicationShutdown)
    {
        Task.Factory.StartNew(() =>
        {
            var sigInt = new UnixSignal(Mono.Unix.Native.Signum.SIGINT);
            var sigTerm = new UnixSignal(Mono.Unix.Native.Signum.SIGTERM);
            Console.WriteLine("To terminate, send SIGINT or SIGTERM to the process");
            UnixSignal.WaitAny(new[] { sigInt, sigTerm });
            Console.WriteLine("Received signal");
            applicationShutdown.RequestShutdown();
        }, TaskCreationOptions.LongRunning);
    }
}

aspnet.service

[Unit]
Description=ASP.NET 5 application

[Service]
WorkingDirectory=/opt/something
User=not-root
ExecStart=/bin/bash kestrel
Environment=TEMP=/tmp
Type=notify
NotifyAccess=main

[Install]
WantedBy=multi-user.target

Startup.Snippet.cs

public void Configure(
    IApplicationLifetime applicationLifetime,
    IApplicationShutdown applicationShutdown
)
{
    applicationLifetime.NotifySystemd();
    applicationShutdown.OnUnixSignals();
}

SystemdStartupNotifier.cs

using System.Runtime.InteropServices;
using Microsoft.AspNet.Hosting;

public static class SystemdStartupNotifier
{
    public static void NotifySystemd(this IApplicationLifetime applicationLifetime)
    {
        applicationLifetime.ApplicationStarted.Register(handler);
    }

    private static void handler()
    {
        sd_notify(0, "READY=1");
    }

    [DllImport("libsystemd.so.0")]
    private static extern int sd_notify(int unset_environment, string state);
}