From 303fc5d786ccf2ad14c8523fc239696c5d37ea53 Mon Sep 17 00:00:00 2001
From: Mark McDowall <mark@mcdowall.ca>
Date: Sat, 4 Feb 2023 00:03:32 -0800
Subject: [PATCH] New: Return static response to requests while app is starting

Closes #5402
---
 .../EnvironmentInfo/IRuntimeInfo.cs           |  1 +
 .../EnvironmentInfo/RuntimeInfo.cs            |  2 +
 src/NzbDrone.Host/AppLifetime.cs              |  1 +
 src/NzbDrone.Host/Startup.cs                  |  1 +
 .../Middleware/StartingUpMiddleware.cs        | 43 +++++++++++++++++++
 5 files changed, 48 insertions(+)
 create mode 100644 src/Sonarr.Http/Middleware/StartingUpMiddleware.cs

diff --git a/src/NzbDrone.Common/EnvironmentInfo/IRuntimeInfo.cs b/src/NzbDrone.Common/EnvironmentInfo/IRuntimeInfo.cs
index a8e4bd9ad..f74ac685a 100644
--- a/src/NzbDrone.Common/EnvironmentInfo/IRuntimeInfo.cs
+++ b/src/NzbDrone.Common/EnvironmentInfo/IRuntimeInfo.cs
@@ -9,6 +9,7 @@ namespace NzbDrone.Common.EnvironmentInfo
         bool IsAdmin { get; }
         bool IsWindowsService { get; }
         bool IsWindowsTray { get; }
+        bool IsStarting { get; set; }
         bool IsExiting { get; set; }
         bool IsTray { get; }
         RuntimeMode Mode { get; }
diff --git a/src/NzbDrone.Common/EnvironmentInfo/RuntimeInfo.cs b/src/NzbDrone.Common/EnvironmentInfo/RuntimeInfo.cs
index 88ab4e4d2..daa2cc449 100644
--- a/src/NzbDrone.Common/EnvironmentInfo/RuntimeInfo.cs
+++ b/src/NzbDrone.Common/EnvironmentInfo/RuntimeInfo.cs
@@ -19,6 +19,7 @@ namespace NzbDrone.Common.EnvironmentInfo
             _logger = logger;
 
             IsWindowsService = hostLifetime is WindowsServiceLifetime;
+            IsStarting = true;
 
             // net6.0 will return Sonarr.dll for entry assembly, we need the actual
             // executable name (Sonarr on linux).  On mono this will return the location of
@@ -82,6 +83,7 @@ namespace NzbDrone.Common.EnvironmentInfo
 
         public bool IsWindowsService { get; private set; }
 
+        public bool IsStarting { get; set; }
         public bool IsExiting { get; set; }
         public bool IsTray
         {
diff --git a/src/NzbDrone.Host/AppLifetime.cs b/src/NzbDrone.Host/AppLifetime.cs
index a1c684f95..946ad1970 100644
--- a/src/NzbDrone.Host/AppLifetime.cs
+++ b/src/NzbDrone.Host/AppLifetime.cs
@@ -56,6 +56,7 @@ namespace NzbDrone.Host
 
         private void OnAppStarted()
         {
+            _runtimeInfo.IsStarting = false;
             _runtimeInfo.IsExiting = false;
 
             if (!_startupContext.Flags.Contains(StartupContext.NO_BROWSER)
diff --git a/src/NzbDrone.Host/Startup.cs b/src/NzbDrone.Host/Startup.cs
index 4121329a6..4226a5e4c 100644
--- a/src/NzbDrone.Host/Startup.cs
+++ b/src/NzbDrone.Host/Startup.cs
@@ -251,6 +251,7 @@ namespace NzbDrone.Host
 
             app.UseMiddleware<VersionMiddleware>();
             app.UseMiddleware<UrlBaseMiddleware>(configFileProvider.UrlBase);
+            app.UseMiddleware<StartingUpMiddleware>();
             app.UseMiddleware<CacheHeaderMiddleware>();
             app.UseMiddleware<IfModifiedMiddleware>();
             app.UseMiddleware<BufferingMiddleware>(new List<string> { "/api/v3/command" });
diff --git a/src/Sonarr.Http/Middleware/StartingUpMiddleware.cs b/src/Sonarr.Http/Middleware/StartingUpMiddleware.cs
new file mode 100644
index 000000000..e26f48d10
--- /dev/null
+++ b/src/Sonarr.Http/Middleware/StartingUpMiddleware.cs
@@ -0,0 +1,43 @@
+using System.Buffers;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
+using NzbDrone.Common.EnvironmentInfo;
+using NzbDrone.Common.Serializer;
+using NzbDrone.Core.Lifecycle;
+using NzbDrone.Core.Messaging.Events;
+using Sonarr.Http.Extensions;
+
+namespace Sonarr.Http.Middleware
+{
+    public class StartingUpMiddleware
+    {
+        private readonly RequestDelegate _next;
+        private readonly IRuntimeInfo _runtimeInfo;
+        private static readonly string MESSAGE = "Sonarr is starting up, please try again later";
+
+        public StartingUpMiddleware(RequestDelegate next, IRuntimeInfo runtimeInfo)
+        {
+            _next = next;
+            _runtimeInfo = runtimeInfo;
+        }
+
+        public async Task InvokeAsync(HttpContext context)
+        {
+            if (_runtimeInfo.IsStarting)
+            {
+                var isJson = context.Request.IsApiRequest();
+                var message = isJson ? STJson.ToJson(new { ErrorMessage = MESSAGE }) : MESSAGE;
+                var bytes = Encoding.UTF8.GetBytes(message);
+
+                context.Response.StatusCode = 503;
+                context.Response.ContentType = isJson ? "application/json" : "text/plain";
+                await context.Response.Body.WriteAsync(bytes, 0, bytes.Length);
+
+                return;
+            }
+
+            await _next(context);
+        }
+    }
+}