From fc79738fcbafa99037cf9a2fc4917a3c78927718 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

(cherry picked from commit 303fc5d786ccf2ad14c8523fc239696c5d37ea53)
---
 .../Middleware/StartingUpMiddleware.cs        | 40 +++++++++++++++++++
 .../EnvironmentInfo/IRuntimeInfo.cs           |  1 +
 .../EnvironmentInfo/RuntimeInfo.cs            |  2 +
 src/NzbDrone.Host/AppLifetime.cs              |  1 +
 src/NzbDrone.Host/Startup.cs                  |  1 +
 5 files changed, 45 insertions(+)
 create mode 100644 src/Lidarr.Http/Middleware/StartingUpMiddleware.cs

diff --git a/src/Lidarr.Http/Middleware/StartingUpMiddleware.cs b/src/Lidarr.Http/Middleware/StartingUpMiddleware.cs
new file mode 100644
index 000000000..486f83e0d
--- /dev/null
+++ b/src/Lidarr.Http/Middleware/StartingUpMiddleware.cs
@@ -0,0 +1,40 @@
+using System.Text;
+using System.Threading.Tasks;
+using Lidarr.Http.Extensions;
+using Microsoft.AspNetCore.Http;
+using NzbDrone.Common.EnvironmentInfo;
+using NzbDrone.Common.Serializer;
+
+namespace Lidarr.Http.Middleware
+{
+    public class StartingUpMiddleware
+    {
+        private readonly RequestDelegate _next;
+        private readonly IRuntimeInfo _runtimeInfo;
+        private static readonly string MESSAGE = "Lidarr 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);
+        }
+    }
+}
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 6751df66a..b77e1d229 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 Lidarr.dll for entry assembly, we need the actual
             // executable name (Lidarr 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 c1a56242d..41ff0165f 100644
--- a/src/NzbDrone.Host/AppLifetime.cs
+++ b/src/NzbDrone.Host/AppLifetime.cs
@@ -57,6 +57,7 @@ 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 84e187c46..951fdb814 100644
--- a/src/NzbDrone.Host/Startup.cs
+++ b/src/NzbDrone.Host/Startup.cs
@@ -265,6 +265,7 @@ 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/v1/command" });