ASP.NET Core Health Checks Tutorial

Introduction

Building a web application is only the first step. Ensuring that it remains available, responsive, and healthy in production is equally important. Modern applications often depend on databases, external APIs, message queues, caches, and other services. If one of these dependencies becomes unavailable, your application may stop functioning correctly.

ASP.NET Core Health Checks provide a standardized way to monitor the health of your application and its dependencies. They help administrators, monitoring tools, and orchestration platforms determine whether an application is running properly and ready to handle requests.

In this tutorial, you'll learn what health checks are, why they're important, how to implement them in ASP.NET Core, and best practices for building reliable applications.

What Are Health Checks?

A health check is an endpoint that reports the status of an application and its dependencies.

Instead of simply checking whether the application is running, health checks can verify the availability of critical components such as:

Databases
External REST APIs
Redis cache
Message queues
Background services
File storage
Cloud services

This information helps detect issues before they affect users.

Why Health Checks Matter

Health checks play an important role in modern application deployment.

Some key benefits include:

Early detection of failures
Improved application monitoring
Faster troubleshooting
Better cloud deployment support
Automatic recovery in containerized environments
Reduced downtime
Improved reliability

Platforms like Kubernetes, Azure App Service, and Docker use health check endpoints to determine whether an application is healthy enough to receive traffic.

Types of Health Checks

ASP.NET Core commonly supports three types of health checks.

Liveness Check

A liveness check verifies whether the application process is running.

If the application fails this check, the hosting platform may restart it automatically.

Readiness Check

A readiness check determines whether the application is ready to accept incoming requests.

For example, the application may still be starting while establishing database connections.

Dependency Check

Dependency checks verify external services such as:

SQL Server
PostgreSQL
Azure Storage
Redis
Third-party APIs

Even if the application is running, failed dependencies can impact functionality.

Register Health Checks

Health checks are registered during application startup.

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddHealthChecks();

This enables the health check framework in your application.

Map the Health Check Endpoint

Next, expose a health endpoint.

var app = builder.Build();

app.MapHealthChecks("/health");

app.Run();

When you browse to:

/health

the application returns its health status.

This endpoint can be monitored by load balancers, monitoring tools, or cloud platforms.

Add a SQL Server Health Check

Most applications depend on a database.

builder.Services.AddHealthChecks()
    .AddSqlServer(
        builder.Configuration.GetConnectionString("DefaultConnection"));

The endpoint now verifies that the database is reachable.

If the database becomes unavailable, the health status changes accordingly.

Monitor Redis

If your application uses Redis for caching, you can include it in your health checks.

builder.Services.AddHealthChecks()
    .AddRedis(
        builder.Configuration.GetConnectionString("Redis"));

This confirms that the cache service is accessible.

Add a Custom Health Check

Sometimes you need to monitor application-specific logic.

Create a custom health check by implementing IHealthCheck.

using Microsoft.Extensions.Diagnostics.HealthChecks;

public class StorageHealthCheck : IHealthCheck
{
    public Task<HealthCheckResult> CheckHealthAsync(
        HealthCheckContext context,
        CancellationToken cancellationToken = default)
    {
        return Task.FromResult(
            HealthCheckResult.Healthy("Storage is available."));
    }
}

builder.Services.AddHealthChecks()
    .AddCheck<StorageHealthCheck>("Storage");

This approach allows you to monitor any custom dependency or business-specific requirement.

Return Detailed Health Information

By default, the endpoint returns a simple status.

You can configure a custom response that includes additional details.

For example, a response may include:

Overall status
Individual component status
Execution time
Failure messages

These details make troubleshooting much easier when an issue occurs.

Health Check Status Values

Health checks typically return one of three states.

Status	Meaning
Healthy	Everything is functioning normally.
Degraded	The application is running but has performance or dependency issues.
Unhealthy	Critical components have failed and immediate attention is required.

Monitoring systems can use these states to trigger alerts or automated recovery actions.

Integrating with Kubernetes

Kubernetes uses health checks to manage containers.

Typical configuration includes:

Liveness probe
Readiness probe
Startup probe

These probes help Kubernetes determine:

When to restart a container
When to stop routing traffic
When a new deployment is ready

Proper health checks improve application availability in containerized environments.

Monitoring Health Checks

Health endpoints are commonly integrated with monitoring platforms such as:

Azure Monitor
Azure Application Insights
Prometheus
Grafana
Datadog
Elastic Stack

These tools continuously monitor application health and notify administrators when problems occur.

Best Practices

Follow these recommendations when implementing health checks:

Monitor all critical dependencies.
Separate liveness and readiness endpoints.
Keep health checks lightweight and fast.
Avoid long-running operations.
Return meaningful health messages.
Secure internal health endpoints if necessary.
Monitor health status continuously using external tools.
Test failure scenarios before deploying to production.

Following these practices helps create reliable and maintainable monitoring solutions.

Common Mistakes to Avoid

Developers often make avoidable mistakes when implementing health checks.

Some common issues include:

Checking only whether the application is running.
Ignoring external dependencies.
Performing expensive operations inside health checks.
Returning sensitive system information.
Using a single endpoint for all monitoring scenarios.
Forgetting to test unhealthy states.

Designing health checks carefully ensures they remain useful without affecting application performance.

Conclusion

ASP.NET Core Health Checks provide a simple yet powerful mechanism for monitoring the health of your application and its dependencies. By exposing standardized endpoints and verifying the availability of databases, caches, external services, and custom components, health checks help detect issues early and support automated recovery in modern deployment environments.

Whether you're deploying to Azure, Docker, or Kubernetes, implementing comprehensive health checks improves application reliability, simplifies monitoring, and reduces downtime. Incorporating health checks into every ASP.NET Core application is a best practice that contributes to more resilient and production-ready software.