ServiceDefaults.HealthChecks 1.2.3

ServiceDefaults.HealthChecks

Production-ready health check infrastructure for ASP.NET Core services with separate liveness, readiness, and startup endpoints - designed for Kubernetes deployments.

Installation

dotnet add package ServiceDefaults.HealthChecks

Quick Start

var builder = WebApplication.CreateBuilder(args);

// Add health check infrastructure
builder.AddHealthCheckDefaults();

// Add PostgreSQL readiness check
builder.AddPostgresReadinessCheck(
    builder.Configuration.GetConnectionString("Postgres")!);

var app = builder.Build();

// Run migrations BEFORE marking ready
using (var scope = app.Services.CreateScope())
{
    var db = scope.ServiceProvider.GetRequiredService<AppDbContext>();
    await db.Database.MigrateAsync();
}

// Mark app as ready AFTER migrations complete
app.MarkAsReady();

// Map health endpoints
app.MapHealthCheckEndpoints();

app.Run();

Health Check Endpoints

Why Separate Endpoints?

Critical Rule: Liveness should NEVER check external dependencies like databases. A database hiccup shouldn't restart your containers.

Kubernetes Configuration

livenessProbe:
  httpGet:
    path: /health/live
    port: 8080
  periodSeconds: 10
  timeoutSeconds: 1
  failureThreshold: 3

readinessProbe:
  httpGet:
    path: /health/ready
    port: 8080
  periodSeconds: 5
  timeoutSeconds: 2
  failureThreshold: 1

startupProbe:
  httpGet:
    path: /health/live
    port: 8080
  failureThreshold: 30
  periodSeconds: 5

API Reference

Builder Extensions

// Add core health checks (liveness + startup state)
builder.AddHealthCheckDefaults();

// Add PostgreSQL readiness check
builder.AddPostgresReadinessCheck(connectionString, name: "postgres", timeout: TimeSpan.FromSeconds(2));

App Extensions

// Map endpoints (defaults: /health/live, /health/ready)
app.MapHealthCheckEndpoints();

// Custom paths
app.MapHealthCheckEndpoints(
    liveEndpoint: "/healthz",
    readyEndpoint: "/ready");

// Mark ready after initialization
app.MarkAsReady();

// Get startup state for manual control
var state = app.GetStartupState();
state.MarkReady();
state.MarkNotReady(); // For graceful shutdown

StartupState

The StartupState class tracks whether your app has completed initialization:

// Injected via DI
public class MyService
{
    private readonly StartupState _startupState;

    public MyService(StartupState startupState)
    {
        _startupState = startupState;
    }

    public bool IsReady => _startupState.IsReady;
}

Response Format

Health endpoints return JSON:

{
  "status": "Healthy",
  "totalDuration": 12.5,
  "checks": [
    {
      "name": "postgres",
      "status": "Healthy",
      "duration": 10.2,
      "description": null,
      "exception": null
    },
    {
      "name": "startup",
      "status": "Healthy",
      "duration": 0.1,
      "description": "Application startup complete",
      "exception": null
    }
  ]
}

License

MIT License