Azure Web App Windows Container Terminated before gracefull shutdown - azure-web-app-service

Question

I've created a .NET Framework Console program which starts and runs some code, then upon exit it should logout of any external services before exiting (gracefully shutdown).
Here is a sample program:
using System;
using System.Runtime.InteropServices;
using System.Threading;
namespace delayed_shutdown
{
class Program
{
public enum CtrlTypes
{
CTRL_C_EVENT = 0,
CTRL_BREAK_EVENT,
CTRL_CLOSE_EVENT,
CTRL_LOGOFF_EVENT = 5,
CTRL_SHUTDOWON_EVENT
}
[DllImport("Kernel32")]
public static extern bool SetConsoleCtrlHandler(HandlerRoutine handler, bool Add);
public delegate bool HandlerRoutine(CtrlTypes CtrlType);
public static volatile HandlerRoutine handlerRoutine = new HandlerRoutine(ConsoleCtrlCheck), true)
public static volatile ManualResetEvent exitEvent = new ManualResetEvent(false);
public static bool ConsoleCtrlCheck(CtrlTypes ctrlType)
{
switch (ctrlType)
{
case CtrlTypes.CTRL_C_EVENT:
Console.WriteLine("CTRL_C received");
exitEvent.Set();
return true;
case CtrlTypes.CTRL_CLOSE_EVENT:
Console.WriteLine("CTRL_CLOSE received");
exitEvent.Set();
return true;
case CtrlTypes.CTRL_BREAK_EVENT:
Console.WriteLine("CTRL_BREAK received");
exitEvent.Set();
return true;
case CtrlTypes.CTRL_LOGOFF_EVENT:
Console.WriteLine("CTRL_LOGOFF received");
exitEvent.Set();
return true;
case CtrlTypes.CTRL_SHUTDOWON_EVENT:
Console.WriteLine("CTRL_SHUTDOWN received");
exitEvent.Set();
return true;
default:
return false;
}
}
static int Main(string[] args)
{
if (!SetConsoleCtrlHandler(handlerRoutine))
{
Console.WriteLine("Error setting up control handler... :(");
return -1;
}
Console.WriteLine("Waiting for control event...");
exitEvent.WaitOne();
var i = 60;
Console.WriteLine($"Exiting in {i} seconds...");
while (i > 0)
{
Console.WriteLine($"{i}");
Thread.Sleep(TimeSpan.FromSeconds(1));
i--;
}
Console.WriteLine("Goodbye");
return 0;
}
}
}
I would have expected Windows Containers running as Azure App Service to trigger "docker stop" like function, which would send SIGTERM to my application.
But what happens is that Azure Web App Windows Container is terminated, after 1 sec of trying to stop the container. How do ask Azure Web App to wait X number of seconds before terminating the windows container?

Answer 1

We are currently working on signaling the process upon stop for Windows Containers on Azure App Service.
In Azure App Service we will default to 5 seconds for waiting for a container to exit upon shutdown but we will allow this to be configurable using the following app setting: WEBSITES_CONTAINER_STOP_TIME_LIMIT and we will allow to wait up to 2 min (WEBSITES_CONTAINER_STOP_TIME_LIMIT=00:02:00)
This capability will be deployed in the next update rollout and I hope to be available worldwide early next year and once it is out we will update our docs too, so please stay tuned.

Answer 2

Intercepting the SIGTERM event is something that isn't currently supported. Since App Service is tailored to HTTP workloads, I am curious though as to the reasoning of having a console app pick up such an event. If you could elaborate further, there may be an alternative such as running your console app as a Web Job instead.