Performing a health check in .NET Core Worker Service

Question

How can I implement health checks in a .NET Core Worker Service?

The service will be run inside Docker and needs to be able to check the health of the service.

Answer 1

Another way of doing this is to implement IHealthCheckPublisher.

The benefits of this approach is the ability to re-use your existing IHealthChecks or integration with 3rd party libraries that rely on IHealthCheck interface (like this one).

Though you still target Microsoft.NET.Sdk.Web as the SDK you don't need to add any asp.net specifics.

Here is an example:

public static IHostBuilder CreateHostBuilder(string[] args) {   return Host     .CreateDefaultBuilder(args)     .ConfigureServices((hostContext, services) =>     {       services         .AddHealthChecks()         .AddCheck<RedisHealthCheck>("redis_health_check")         .AddCheck<RfaHealthCheck>("rfa_health_check");        services.AddSingleton<IHealthCheckPublisher, HealthCheckPublisher>();       services.Configure<HealthCheckPublisherOptions>(options =>       {         options.Delay = TimeSpan.FromSeconds(5);         options.Period = TimeSpan.FromSeconds(5);       });     }); }  public class HealthCheckPublisher : IHealthCheckPublisher {   private readonly string _fileName;   private HealthStatus _prevStatus = HealthStatus.Unhealthy;    public HealthCheckPublisher()   {     _fileName = Environment.GetEnvironmentVariable(EnvVariableNames.DOCKER_HEALTHCHECK_FILEPATH) ??                 Path.GetTempFileName();   }    public Task PublishAsync(HealthReport report, CancellationToken cancellationToken)   {     // AWS will check if the file exists inside of the container with the command     // test -f $DOCKER_HEALTH_CHECK_FILEPATH      var fileExists = _prevStatus == HealthStatus.Healthy;      if (report.Status == HealthStatus.Healthy)     {       if (!fileExists)       {         using var _ = File.Create(_fileName);       }     }     else if (fileExists)     {       File.Delete(_fileName);     }      _prevStatus = report.Status;      return Task.CompletedTask;   } }