Aspire Service Defaults

What the source does

• FilesystemNone observedNo reads or writes in the source
• NetworkNone observedNo outbound calls in the source
• ShellNone observedNo commands run in the source
• DependenciesPinnedNothing floats
• SecretsNone foundNo keys in source

Five audit layers

Gates applied: no behavioural pass.

CLAUDE.md

Audit 0.4.1 · source sha 871f73ffcae3 · 18 Oct 2026Report an issue or request a re-scan

• PublisherAaronontheweb GitHub userOwner of the repository this skill is read from
• Source folderAaronontheweb/dotnet-skills/skills/aspire-service-defaultsThe exact folder we audited
• LicenceMITAs the repository states it
• Commit pinned for this verdict871f73ffcae3A new audit runs when the source changes
• Repository statusNot archivedLast push 7 days ago
• Sandboxed runNot runSkills are read, not executed; layer L4 is skipped

Its description: Create a shared ServiceDefaults project for Aspire applications. Centralizes OpenTelemetry, health checks, resilience, and service discovery configuration across all services.

---
name: aspire-service-defaults
description: Create a shared ServiceDefaults project for Aspire applications. Centralizes OpenTelemetry, health checks, resilience, and service discovery configuration across all services.
user-invocable: false
---

# Aspire Service Defaults

## When to Use This Skill

Use this skill when:
- Building Aspire-based distributed applications
- Need consistent observability (logging, tracing, metrics) across services
- Want shared health check configuration
- Configuring HttpClient resilience and service discovery

---

## What is ServiceDefaults?

ServiceDefaults is a shared project that provides common configuration for all services in an Aspire application:

- **OpenTelemetry** - Logging, tracing, and metrics
- **Health Checks** - Readiness and liveness endpoints
- **Service Discovery** - Automatic service resolution
- **HTTP Resilience** - Retry and circuit breaker policies

Every service references this project and calls `AddServiceDefaults()`.

---

## Project Structure

```
src/
  MyApp.ServiceDefaults/
    Extensions.cs
    MyApp.ServiceDefaults.csproj
  MyApp.Api/
    Program.cs  # Calls AddServiceDefaults()
  MyApp.Worker/
    Program.cs  # Calls AddServiceDefaults()
  MyApp.AppHost/
    Program.cs
```

---

## ServiceDefaults Project

### Project File

```xml
<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net9.0</TargetFramework>
    <IsAspireSharedProject>true</IsAspireSharedProject>
  </PropertyGroup>

  <ItemGroup>
    <FrameworkReference Include="Microsoft.AspNetCore.App" />
    <PackageReference Include="Microsoft.Extensions.Http.Resilience" />
    <PackageReference Include="Microsoft.Extensions.ServiceDiscovery" />
    <PackageReference Include="OpenTelemetry.Exporter.OpenTelemetryProtocol" />
    <PackageReference Include="OpenTelemetry.Extensions.Hosting" />
    <PackageReference Include="OpenTelemetry.Instrumentation.AspNetCore" />
    <PackageReference Include="OpenTelemetry.Instrumentation.Http" />
    <PackageReference Include="OpenTelemetry.Instrumentation.Runtime" />
  </ItemGroup>
</Project>
```

### Extensions.cs

```csharp
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Diagnostics.HealthChecks;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Diagnostics.HealthChecks;
using Microsoft.Extensions.Logging;
using OpenTelemetry;
using OpenTelemetry.Metrics;
using OpenTelemetry.Trace;

namespace Microsoft.Extensions.Hosting;

public static class Extensions
{
    private const string HealthEndpointPath = "/health";
    private const string AlivenessEndpointPath = "/alive";

    /// <summary>
    /// Adds common Aspire services: OpenTelemetry, health checks,
    /// service discovery, and HTTP resilience.
    /// </summary>
    public static TBuilder AddServiceDefaults<TBuilder>(this TBuilder builder)
        where TBuilder : IHostApplicationBuilder
    {
        builder.ConfigureOpenTelemetry();
        builder.AddDefaultHealthChecks();

        builder.Services.AddServiceDiscovery();

        builder.Services.ConfigureHttpClientDefaults(http =>
        {
            // Resilience: retries, circuit breaker, timeouts
            http.AddStandardResilienceHandler();

            // Service discovery: resolve service names to addresses
            http.AddServiceDiscovery();
        });

        return builder;
    }

    public static TBuilder ConfigureOpenTelemetry<TBuilder>(this TBuilder builder)
        where TBuilder : IHostApplicationBuilder
    {
        // Logging
        builder.Logging.AddOpenTelemetry(logging =>
        {
            logging.IncludeFormattedMessage = true;
            logging.IncludeScopes = true;
        });

        builder.Services.AddOpenTelemetry()
            // Metrics
            .WithMetrics(metrics =>
            {
                metrics
                    .AddAspNetCoreInstrumentation()
                    .AddHttpClientInstrumentation()
                    .AddRuntimeInstrumentation();
            })
            // Tracing
            .WithTracing(tracing =>
            {
                tracing
                    .AddSource(builder.Environment.ApplicationName)
                    .AddAspNetCoreInstrumentation(options =>
                        // Exclude health checks from traces
                        options.Filter = context =>
                            !context.Request.Path.StartsWithSegments(HealthEndpointPath) &&
                            !context.Request.Path.StartsWithSegments(AlivenessEndpointPath))
                    .AddHttpClientInstrumentation();
            });

        builder.AddOpenTelemetryExporters();

        return builder;
    }

    private static TBuilder AddOpenTelemetryExporters<TBuilder>(this TBuilder builder)
        where TBuilder : IHostApplicationBuilder
    {
        // Use OTLP exporter if endpoint is configured (Aspire Dashboard, Jaeger, etc.)
        var useOtlp = !string.IsNullOrWhiteSpace(
            builder.Configuration["OTEL_EXPORTER_OTLP_ENDPOINT"]);

        if (useOtlp)
        {
            builder.Services.AddOpenTelemetry().UseOtlpExporter();
        }

        return builder;
    }

    public static TBuilder AddDefaultHealthChecks<TBuilder>(this TBuilder builder)
        where TBuilder : IHostApplicationBuilder
    {
        builder.Services.AddHealthChecks()
            .AddCheck("self", () => HealthCheckResult.Healthy(), ["live"]);

        return builder;
    }

    /// <summary>
    /// Maps health check endpoints. Call after UseRouting().
    /// </summary>
    public static WebApplication MapDefaultEndpoints(this WebApplication app)
    {
        // Only expose in development - see security note below
        if (app.Environment.IsDevelopment())
        {
            // Readiness: all health checks must pass
            app.MapHealthChecks(HealthEndpointPath);

            // Liveness: only "live" tagged checks
            app.MapHealthChecks(AlivenessEndpointPath, new Hea

Excerpt, first 6,000 characters of SKILL.md, verbatim from the audited commit. It is text from someone else’s repository, quoted so you can judge it before your agent reads it.

git clone https://github.com/Aaronontheweb/dotnet-skills
git -C dotnet-skills checkout 871f73ffcae3

Works in

1. 2026-10-18
   ✓SAFE B 89 / 100

   first audit · source 871f73ffcae3

Questions about Aspire Service Defaults

• github.com/Aaronontheweb/dotnet-skills/tree/master/skills/aspire — the audited source at commit 871f73ffcae3 and every finding aboveObserved · 18 Oct 2026

Spotted something wrong? Report a correction · Methodology