ARCH-2: add Aspire AppHost + ServiceDefaults (Aspire 13.4.2)

- New projects GerbilManager.AppHost / GerbilManager.ServiceDefaults (templates)
- Added both to GerbilManager.slnx
- WebAPI references ServiceDefaults; AddServiceDefaults + MapDefaultEndpoints wired

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

GerbilManager.AppHost/AppHost.cs

@@ -0,0 +1,3 @@
+var builder = DistributedApplication.CreateBuilder(args);
+
+builder.Build().Run();

GerbilManager.AppHost/GerbilManager.AppHost.csproj

@@ -0,0 +1,11 @@
+<Project Sdk="Aspire.AppHost.Sdk/13.4.2">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net10.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <UserSecretsId>b153f50c-bec1-401e-9893-f9df7cff2ebd</UserSecretsId>
+  </PropertyGroup>
+
+</Project>

GerbilManager.AppHost/Properties/launchSettings.json

@@ -0,0 +1,29 @@
+{
+  "$schema": "https://json.schemastore.org/launchsettings.json",
+  "profiles": {
+    "https": {
+      "commandName": "Project",
+      "dotnetRunMessages": true,
+      "launchBrowser": true,
+      "applicationUrl": "https://localhost:17004;http://localhost:15265",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development",
+        "DOTNET_ENVIRONMENT": "Development",
+        "ASPIRE_DASHBOARD_OTLP_ENDPOINT_URL": "https://localhost:21284",
+        "ASPIRE_RESOURCE_SERVICE_ENDPOINT_URL": "https://localhost:22112"
+      }
+    },
+    "http": {
+      "commandName": "Project",
+      "dotnetRunMessages": true,
+      "launchBrowser": true,
+      "applicationUrl": "http://localhost:15265",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development",
+        "DOTNET_ENVIRONMENT": "Development",
+        "ASPIRE_DASHBOARD_OTLP_ENDPOINT_URL": "http://localhost:19171",
+        "ASPIRE_RESOURCE_SERVICE_ENDPOINT_URL": "http://localhost:20259"
+      }
+    }
+  }
+}

GerbilManager.AppHost/appsettings.Development.json

@@ -0,0 +1,8 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  }
+}

GerbilManager.AppHost/appsettings.json

@@ -0,0 +1,9 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning",
+      "Aspire.Hosting.Dcp": "Warning"
+    }
+  }
+}

GerbilManager.AppHost/aspire.config.json

@@ -0,0 +1,5 @@
+{
+  "appHost": {
+    "path": "GerbilManager.AppHost.csproj"
+  }
+}

GerbilManager.ServiceDefaults/Extensions.cs

@@ -0,0 +1,127 @@
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Diagnostics.HealthChecks;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Diagnostics.HealthChecks;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.ServiceDiscovery;
+using OpenTelemetry;
+using OpenTelemetry.Metrics;
+using OpenTelemetry.Trace;
+
+namespace Microsoft.Extensions.Hosting;
+
+// Adds common Aspire services: service discovery, resilience, health checks, and OpenTelemetry.
+// This project should be referenced by each service project in your solution.
+// To learn more about using this project, see https://aka.ms/aspire/service-defaults
+public static class Extensions
+{
+    private const string HealthEndpointPath = "/health";
+    private const string AlivenessEndpointPath = "/alive";
+
+    public static TBuilder AddServiceDefaults<TBuilder>(this TBuilder builder) where TBuilder : IHostApplicationBuilder
+    {
+        builder.ConfigureOpenTelemetry();
+
+        builder.AddDefaultHealthChecks();
+
+        builder.Services.AddServiceDiscovery();
+
+        builder.Services.ConfigureHttpClientDefaults(http =>
+        {
+            // Turn on resilience by default
+            http.AddStandardResilienceHandler();
+
+            // Turn on service discovery by default
+            http.AddServiceDiscovery();
+        });
+
+        // Uncomment the following to restrict the allowed schemes for service discovery.
+        // builder.Services.Configure<ServiceDiscoveryOptions>(options =>
+        // {
+        //     options.AllowedSchemes = ["https"];
+        // });
+
+        return builder;
+    }
+
+    public static TBuilder ConfigureOpenTelemetry<TBuilder>(this TBuilder builder) where TBuilder : IHostApplicationBuilder
+    {
+        builder.Logging.AddOpenTelemetry(logging =>
+        {
+            logging.IncludeFormattedMessage = true;
+            logging.IncludeScopes = true;
+        });
+
+        builder.Services.AddOpenTelemetry()
+            .WithMetrics(metrics =>
+            {
+                metrics.AddAspNetCoreInstrumentation()
+                    .AddHttpClientInstrumentation()
+                    .AddRuntimeInstrumentation();
+            })
+            .WithTracing(tracing =>
+            {
+                tracing.AddSource(builder.Environment.ApplicationName)
+                    .AddAspNetCoreInstrumentation(tracing =>
+                        // Exclude health check requests from tracing
+                        tracing.Filter = context =>
+                            !context.Request.Path.StartsWithSegments(HealthEndpointPath)
+                            && !context.Request.Path.StartsWithSegments(AlivenessEndpointPath)
+                    )
+                    // Uncomment the following line to enable gRPC instrumentation (requires the OpenTelemetry.Instrumentation.GrpcNetClient package)
+                    //.AddGrpcClientInstrumentation()
+                    .AddHttpClientInstrumentation();
+            });
+
+        builder.AddOpenTelemetryExporters();
+
+        return builder;
+    }
+
+    private static TBuilder AddOpenTelemetryExporters<TBuilder>(this TBuilder builder) where TBuilder : IHostApplicationBuilder
+    {
+        var useOtlpExporter = !string.IsNullOrWhiteSpace(builder.Configuration["OTEL_EXPORTER_OTLP_ENDPOINT"]);
+
+        if (useOtlpExporter)
+        {
+            builder.Services.AddOpenTelemetry().UseOtlpExporter();
+        }
+
+        // Uncomment the following lines to enable the Azure Monitor exporter (requires the Azure.Monitor.OpenTelemetry.AspNetCore package)
+        //if (!string.IsNullOrEmpty(builder.Configuration["APPLICATIONINSIGHTS_CONNECTION_STRING"]))
+        //{
+        //    builder.Services.AddOpenTelemetry()
+        //       .UseAzureMonitor();
+        //}
+
+        return builder;
+    }
+
+    public static TBuilder AddDefaultHealthChecks<TBuilder>(this TBuilder builder) where TBuilder : IHostApplicationBuilder
+    {
+        builder.Services.AddHealthChecks()
+            // Add a default liveness check to ensure app is responsive
+            .AddCheck("self", () => HealthCheckResult.Healthy(), ["live"]);
+
+        return builder;
+    }
+
+    public static WebApplication MapDefaultEndpoints(this WebApplication app)
+    {
+        // Adding health checks endpoints to applications in non-development environments has security implications.
+        // See https://aka.ms/aspire/healthchecks for details before enabling these endpoints in non-development environments.
+        if (app.Environment.IsDevelopment())
+        {
+            // All health checks must pass for app to be considered ready to accept traffic after starting
+            app.MapHealthChecks(HealthEndpointPath);
+
+            // Only health checks tagged with the "live" tag must pass for app to be considered alive
+            app.MapHealthChecks(AlivenessEndpointPath, new HealthCheckOptions
+            {
+                Predicate = r => r.Tags.Contains("live")
+            });
+        }
+
+        return app;
+    }
+}

GerbilManager.ServiceDefaults/GerbilManager.ServiceDefaults.csproj

@@ -0,0 +1,22 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <IsAspireSharedProject>true</IsAspireSharedProject>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <FrameworkReference Include="Microsoft.AspNetCore.App" />
+
+    <PackageReference Include="Microsoft.Extensions.Http.Resilience" Version="10.6.0" />
+    <PackageReference Include="Microsoft.Extensions.ServiceDiscovery" Version="10.6.0" />
+    <PackageReference Include="OpenTelemetry.Exporter.OpenTelemetryProtocol" Version="1.15.3" />
+    <PackageReference Include="OpenTelemetry.Extensions.Hosting" Version="1.15.3" />
+    <PackageReference Include="OpenTelemetry.Instrumentation.AspNetCore" Version="1.15.2" />
+    <PackageReference Include="OpenTelemetry.Instrumentation.Http" Version="1.15.1" />
+    <PackageReference Include="OpenTelemetry.Instrumentation.Runtime" Version="1.15.1" />
+  </ItemGroup>
+
+</Project>

GerbilManager.slnx

@@ -1,3 +1,5 @@
 <Solution>
+  <Project Path="GerbilManager.AppHost/GerbilManager.AppHost.csproj" />
+  <Project Path="GerbilManager.ServiceDefaults/GerbilManager.ServiceDefaults.csproj" />
   <Project Path="GerbilManagerWebAPI/GerbilManagerWebAPI.csproj" />
 </Solution>

GerbilManagerWebAPI/GerbilManagerWebAPI.csproj

@@ -17,4 +17,8 @@
     <PackageReference Include="Swashbuckle.AspNetCore" Version="10.2.1" />
   </ItemGroup>
 
+  <ItemGroup>
+    <ProjectReference Include="..\GerbilManager.ServiceDefaults\GerbilManager.ServiceDefaults.csproj" />
+  </ItemGroup>
+
 </Project>

GerbilManagerWebAPI/Program.cs

@@ -3,6 +3,8 @@ using Microsoft.EntityFrameworkCore;
 
 var builder = WebApplication.CreateBuilder(args);
 
+builder.AddServiceDefaults();
+
 // Add services to the container.
 
 builder.Services.AddControllers();
@@ -14,6 +16,8 @@ builder.Services.AddScoped<UnitOfWork>();
 
 var app = builder.Build();
 
+app.MapDefaultEndpoints();
+
 // Configure the HTTP request pipeline.
 if (app.Environment.IsDevelopment())
 {