Bits of .NET

Need to know if your app is healthy? Health checks provide monitoring endpoints automatically.

Setup:

// Program.cs
builder.Services.AddHealthChecks()
    .AddDbContextCheck()  // Check database
    .AddUrlGroup(new Uri("https://api.example.com"), "External API");  // Check external dependency

var app = builder.Build();
app.MapHealthChecks("/health");

Test:

curl http://localhost:5000/health

# Healthy response: 200 OK
# Unhealthy: 503 Service Unavailable

Custom Health Check:

public class MemoryHealthCheck : IHealthCheck
{
    public Task CheckHealthAsync(HealthCheckContext context)
    {
        var allocatedMemory = GC.GetTotalMemory(false);
        var threshold = 1024 * 1024 * 1024; // 1 GB
        
        return Task.FromResult(
            allocatedMemory < threshold 
                ? HealthCheckResult.Healthy("Memory usage normal")
                : HealthCheckResult.Unhealthy("Memory usage high")
        );
    }
}

builder.Services.AddHealthChecks()
    .AddCheck("memory");

Kubernetes/Docker use this to know when to restart containers!