[ODS-5623] Make the Swagger Startup configurable

Application/EdFi.Ods.SwaggerUI/Program.cs

@@ -4,22 +4,32 @@
 // See the LICENSE and NOTICES files in the project root for more information.
 
 using System;
+using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 
 namespace EdFi.Ods.SwaggerUI
 {
     public class Program
     {
+        private const string MissingStartupClassMessage =
+            "Could not find the startup class. No loaded class member could be found matching the configured startup class name '{0}'.";
+        private const string DefaultStartupClassName = "Startup";
+
         public static async Task Main(string[] args)
         {
             await CreateHostBuilder(args).Build().RunAsync();
         }
 
-        public static IHostBuilder CreateHostBuilder(string[] args)
-            => Host.CreateDefaultBuilder(args)
+        private static IHostBuilder CreateHostBuilder(string[] args)
+        {
+            var startupClassName = GetStartupClassName(args);
+            var startupType = FindStartupClassType(startupClassName);
+
+            return Host.CreateDefaultBuilder(args)
                 .ConfigureWebHostDefaults(
                     webBuilder =>
                     {
@@ -28,8 +38,29 @@ public static IHostBuilder CreateHostBuilder(string[] args)
                             {
                                 serverOptions.AddServerHeader = false;
                             });
-
-                        webBuilder.UseStartup<Startup>();
+                        webBuilder.UseStartup(startupType);
                     });
+        }
+
+        private static string GetStartupClassName(string[] args)
+        {
+            using var hostBuilder = Host.CreateDefaultBuilder(args).Build();
+            var config = hostBuilder.Services.GetService<IConfiguration>();
+            return config?.GetSection("SwaggerUIOptions").GetValue<string>("StartupClassName") ?? DefaultStartupClassName;
+        }
+
+        private static Type FindStartupClassType(string startupClassName)
+        {
+            var startupType = AppDomain.CurrentDomain.GetAssemblies()
+                .SelectMany(assembly => assembly.GetTypes())
+                .FirstOrDefault(t => t.Name == startupClassName);
+
+            if (startupType == null)
+            {
+                throw new MissingMemberException(string.Format(MissingStartupClassMessage, startupClassName));
+            }
+
+            return startupType;
+        }
     }
 }

Application/EdFi.Ods.SwaggerUI/appsettings.json

@@ -1,6 +1,7 @@
 {
   "WebApiVersionUrl": "",
   "SwaggerUIOptions": {
+    "StartupClassName": "Startup",
     "OAuthConfigObject": {
       "ClientId": "",
       "ClientSecret": ""