Added diagnostic entry for basic server info

Author: bhazen

identity-server/src/IdentityServer/Configuration/DependencyInjection/BuilderExtensions/Core.cs

@@ -4,6 +4,7 @@
 
 #nullable enable
 
+using System.Net;
 using Duende.IdentityServer;
 using Duende.IdentityServer.Configuration;
 using Duende.IdentityServer.Configuration.DependencyInjection;
@@ -220,6 +221,7 @@ public static IIdentityServerBuilder AddCoreServices(this IIdentityServerBuilder
         builder.Services.AddSingleton<IDiagnosticEntry, DataProtectionDiagnosticEntry>();
         builder.Services.AddSingleton<IDiagnosticEntry, TokenIssueCountDiagnosticEntry>();
         builder.Services.AddSingleton<IDiagnosticEntry, LicenseUsageDiagnosticEntry>();
+        builder.Services.AddSingleton<IDiagnosticEntry>(new BasicServerInfoDiagnosticEntry(Dns.GetHostName));
         builder.Services.AddSingleton<DiagnosticSummary>();
         builder.Services.AddHostedService<DiagnosticHostedService>();
 

identity-server/src/IdentityServer/Licensing/V2/Diagnostics/DiagnosticEntries/BasicServerInfoDiagnosticEntry.cs

@@ -0,0 +1,20 @@
+// Copyright (c) Duende Software. All rights reserved.
+// See LICENSE in the project root for license information.
+
+using System.Text.Json;
+
+namespace Duende.IdentityServer.Licensing.V2.Diagnostics.DiagnosticEntries;
+
+internal class BasicServerInfoDiagnosticEntry(Func<string> hostNameResolver) : IDiagnosticEntry
+{
+    public Task WriteAsync(Utf8JsonWriter writer)
+    {
+        writer.WriteStartObject("BasicServerInfo");
+
+        writer.WriteString("HostName", hostNameResolver());
+
+        writer.WriteEndObject();
+
+        return Task.CompletedTask;
+    }
+}

identity-server/test/IdentityServer.UnitTests/Licensing/v2/DiagnosticEntries/BasicServerInfoDiagnosticEntryTests.cs

@@ -0,0 +1,22 @@
+// Copyright (c) Duende Software. All rights reserved.
+// See LICENSE in the project root for license information.
+
+using Duende.IdentityServer.Licensing.V2.Diagnostics.DiagnosticEntries;
+using IdentityServer.UnitTests.Licensing.V2.DiagnosticEntries;
+
+namespace IdentityServer.UnitTests.Licensing.v2.DiagnosticEntries;
+
+public class BasicServerInfoDiagnosticEntryTests
+{
+    [Fact]
+    public async Task WriteAsync_ShouldWriteBasicServerInfo()
+    {
+        const string expectedHostName = "testing.local";
+        var subject = new BasicServerInfoDiagnosticEntry(() => expectedHostName);
+
+        var result = await DiagnosticEntryTestHelper.WriteEntryToJson(subject);
+
+        var basicServerInfo = result.RootElement.GetProperty("BasicServerInfo");
+        basicServerInfo.GetProperty("HostName").GetString().ShouldBe(expectedHostName);
+    }
+}