.NET Core Workerservice - 如何在没有 HTTP 的情况下提供运行状况检查端点？

Question

我构建了一个在 kubernetes 上运行的 ASP.NET Core Worker Service（它处理队列中的消息）。由于它是后台服务，因此目前没有任何 HTTP 端点。现在我想向其中添加 k8s 的运行状况/活跃性端点 - 最好利用.NET Core 标准运行状况检查。

所以我的问题是：有没有一种方法可以公开这些运行状况检查，而无需以 k8s 可以使用它们的方式（TCP 或通用命令）增加 HTTP 端点的开销？任何指向示例的指针都会很棒！谢谢！

Answer 1

感谢 @pinkfloydx33 的指点，我能够构建这个解决方案：

程序.cs

public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
    .ConfigureServices((hostContext, services) =>
    {
        services.AddHealthChecks() // Register some real health check here ==>
            .AddCheck("test", () => DateTime.UtcNow.Minute % 2 == 0 ? HealthCheckResult.Healthy() : HealthCheckResult.Unhealthy());
        services.AddSingleton<IHealthCheckPublisher, HealthCheckPublisher>();
        services.Configure<HealthCheckPublisherOptions>(options =>
        {
            options.Delay = TimeSpan.FromSeconds(5);
            options.Period = TimeSpan.FromSeconds(20);
        });

        // Register the actual message processor service
        services.AddHostedService<QueueProcessorService>();
    })

HealthCheckPublisher.cs

public class HealthCheckPublisher : IHealthCheckPublisher
{
    private readonly string _fileName;
    private HealthStatus _prevStatus = HealthStatus.Unhealthy;

    public HealthCheckPublisher()
    {
        _fileName = Environment.GetEnvironmentVariable("DOCKER_HEALTHCHECK_FILEPATH") ??
                    Path.GetTempFileName();
    }

    /// <summary>
    /// Creates / touches a file on the file system to indicate "healtyh" (liveness) state of the pod
    /// Deletes the files to indicate "unhealthy"
    /// The file will then be checked by k8s livenessProbe
    /// </summary>
    /// <param name="report"></param>
    /// <param name="cancellationToken"></param>
    /// <returns></returns>
    public Task PublishAsync(HealthReport report, CancellationToken cancellationToken)
    {
        var fileExists = _prevStatus == HealthStatus.Healthy;

        if (report.Status == HealthStatus.Healthy)
        {
            using var _ = File.Create(_fileName);
        }
        else if (fileExists)
        {
            File.Delete(_fileName);
        }

        _prevStatus = report.Status;

        return Task.CompletedTask;
    }
}

k8s部署.yaml（原始来源：https://medium.com/spire-labs/utilizing-kubernetes-liveness-and-readiness-probes-to-automatically-recover-from-failure-2fe0314f2b2e）

感谢@zimbres 指出了活性探针中的缺陷。现在这是更新版本：

public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
    .ConfigureServices((hostContext, services) =>
    {
        services.AddHealthChecks() // Register some real health check here ==>
            .AddCheck("test", () => DateTime.UtcNow.Minute % 2 == 0 ? HealthCheckResult.Healthy() : HealthCheckResult.Unhealthy());
        services.AddSingleton<IHealthCheckPublisher, HealthCheckPublisher>();
        services.Configure<HealthCheckPublisherOptions>(options =>
        {
            options.Delay = TimeSpan.FromSeconds(5);
            options.Period = TimeSpan.FromSeconds(20);
        });

        // Register the actual message processor service
        services.AddHostedService<QueueProcessorService>();
    })