UnrealEngineUWP/Engine/Source/Programs/Horde/Horde.Build/Controllers/LifetimeController.cs

// Copyright Epic Games, Inc. All Rights Reserved.

using HordeServer.Services;
using Microsoft.AspNetCore.Mvc;
using System.Threading.Tasks;

namespace HordeServer.Controllers
{
	/// <summary>
	/// Controller for app lifetime related routes
	/// </summary>
	[ApiController]
	[Route("[controller]")]
	public class LifetimeController : ControllerBase
	{
		/// <summary>
		/// Singleton instance of the lifetime service
		/// </summary>
		LifetimeService LifetimeService;

		/// <summary>
		/// Constructor
		/// </summary>
		/// <param name="LifetimeService">The lifetime service singleton</param>
		public LifetimeController(LifetimeService LifetimeService)
		{
			this.LifetimeService = LifetimeService;
		}

		/// <summary>
		/// Readiness check for server
		/// 
		/// When a SIGTERM has been received, the server is shutting down.
		/// To communicate the server is stopping to load balancers/orchestrators, this route will return either 503 or 200.
		/// The server will continue to serve requests, but it's assumed the load balancer has reacted and stopped sending
		/// traffic by the time the server process exits.
		/// </summary>
		/// <returns>Status code 503 is server is stopping, else 200 OK</returns>
		[HttpGet]
		[Route("/health/ready")]
		public Task<ActionResult> ServerReadiness()
		{
			int StatusCode = 200;
			string Content = "ok";
			
			if (LifetimeService.IsPreStopping)
			{
				StatusCode = 503; // Service Unavailable
				Content = "stopping";
			}

			return Task.FromResult<ActionResult>(new ContentResult { ContentType = "text/plain", StatusCode = StatusCode, Content = Content });
		}
		
		/// <summary>
		/// Liveness check for Kubernetes
		/// If this return a non-successful HTTP response, Kubernetes will kill the pod and restart it
		/// </summary>
		/// <returns>Ok if app is not stopping and all databases can be reached</returns>
		[HttpGet]
		[Route("/health/live")]
		public ActionResult K8sLivenessProbe()
		{
			return new ContentResult { ContentType = "text/plain", StatusCode = 200, Content = "ok" };
		}
	}
}