.net core 健康检测

• .net core 健康检测
  • 检查应用的健康状态
  • 确定当前应用是否可用
  • 定制健康检查逻辑
  • 改变响应状态码
  • 细粒度的健康检查
  • 定制响应内容
  • 过滤 IHealthCheck 对象
  • 针对 Entity Framework Core 的健康检查
    • 基于 DbContext 的健康检查
    • 发布健康报告
  • 健康检查(UI)
    • HealthChecks
    • Webhooks
    • EvaluationTimeinSeconds
    • MinimumSecondsBetweenFailureNotifications
    • UI自定义样式表
  • HealthCheck 与 Kubernetes

检查应用的健康状态

确定当前应用是否可用

class Program
{
    static void Main(string[] args)
    {
        Host.CreateDefaultBuilder()
            .ConfigureWebHostDefaults(builder=>builder
                                      .ConfigureServices(svcs=>svcs.AddHealthChecks())
                                      .Configure(app=>app.UseHealthChecks("/healthcheck")))
            .Build()
            .Run();
    }
}

定制健康检查逻辑

    class Program
    {
        static void Main(string[] args)
        {
            var random = new Random();
            Host.CreateDefaultBuilder()
                .ConfigureWebHostDefaults(builder=>builder
                    .ConfigureServices(svcs=>svcs.AddHealthChecks()
                        .AddCheck("default",Check))
                    .Configure(app=>app.UseHealthChecks("/healthcheck")))
                .Build()
                .Run();
            HealthCheckResult Check()
            {
                return (random.Next(1,4)) switch
                {
                    1 => HealthCheckResult.Unhealthy(),
                    2 => HealthCheckResult.Degraded(),
                    _ => HealthCheckResult.Healthy()
                };
            }
        }
    }

改变响应状态码

    class Program
    {
        static void Main(string[] args)
        {
            var random = new Random();
            var option = new HealthCheckOptions{
                ResultStatusCodes = new Dictionary<HealthStatus,int>{
                    [HealthStatus.Healthy] = 99,
                    [HealthStatus.Degraded] = 299,
                    [HealthStatus.Unhealthy] = 503
                }
            };
            Host.CreateDefaultBuilder()
                .ConfigureWebHostDefaults(builder=>builder
                    .ConfigureServices(svcs=>svcs.AddHealthChecks()
                        .AddCheck("default",Check))
                    .Configure(app=>app.UseHealthChecks("/healthcheck",option)))
                .Build()
                .Run();
            HealthCheckResult Check()
            {
                return (random.Next(1,4)) switch
                {
                    1 => HealthCheckResult.Unhealthy(),
                    2 => HealthCheckResult.Degraded(),
                    _ => HealthCheckResult.Healthy()
                };
            }
        }
    }

细粒度的健康检查

    class Program
    {
        static void Main(string[] args)
        {
            var random = new Random();
            Host.CreateDefaultBuilder()
                .ConfigureWebHostDefaults(builder=>builder
                    .ConfigureServices(svcs=>svcs.AddHealthChecks()
                        .AddCheck("aaa",Check)
                        .AddCheck("bbb",Check)
                        .AddCheck("ccc",Check))
                    .Configure(app=>app.UseHealthChecks("/healthcheck")))
                .Build()
                .Run();
            HealthCheckResult Check()
            {
                return (random.Next(1,4)) switch
                {
                    1 => HealthCheckResult.Unhealthy(),
                    2 => HealthCheckResult.Degraded(),
                    _ => HealthCheckResult.Healthy()
                };
            }
        }
    }

从这个案例可以反应出所有得到的结果有点以面盖全了，如果是Healthy那么所有的服务以及所依赖的组件都是Healthy,…所以这并不是我们想要的，应该对服务与依赖进行定制响应内容。

定制响应内容

    class Program
    {
        static void Main(string[] args)
        {
            var random = new Random();
            var options = new HealthCheckOptions{
                ResponseWriter = ReportAsync
            };
            Host.CreateDefaultBuilder()
                .ConfigureWebHostDefaults(builder=>builder
                    .ConfigureServices(svcs=>svcs.AddHealthChecks()
                        .AddCheck("aaa",Check,new string[]{ "aaa1","bbb2" })
                        .AddCheck("bbb",Check,new string[]{ "bbb1","bbb2" })
                        .AddCheck("ccc",Check,new string[]{ "ccc1","ccc1" }))
                    .Configure(app=>app.UseHealthChecks("/healthcheck",options)))
                .Build()
                .Run();
            static Task ReportAsync(Microsoft.AspNetCore.Http.HttpContext content,HealthReport report){
                content.Response.ContentType = "application/json";
                var settings = new JsonSerializerSettings();
                settings.Formatting = Formatting.Indented;
                settings.Converters.Add(new StringEnumConverter());
                return content.Response.WriteAsync(JsonConvert.SerializeObject(report,settings));
            }
            HealthCheckResult Check()
            {
                return (random.Next(1,4)) switch
                {
                    1 => HealthCheckResult.Unhealthy("Unavailable"),
                    2 => HealthCheckResult.Degraded("Degraded"),
                    _ => HealthCheckResult.Healthy("Normal")
                };
            }
        }
    }

过滤 IHealthCheck 对象

class Program
{
    static void Main(string[] args)
    {
        var random = new Random();
        var options = new HealthCheckOptions
        {
            ResponseWriter = ReportAsync,
            Predicate = reg => reg.Tags.Any(tag => !tag.StartsWith("ccc", StringComparison.OrdinalIgnoreCase))
        };
        Host.CreateDefaultBuilder()
            .ConfigureWebHostDefaults(builder => builder
                .ConfigureServices(svcs => svcs
                    .AddHealthChecks()
                        .AddCheck("aaa", Check, new string[] { "aaa1", "bbb2" })
                        .AddCheck("bbb", Check, new string[] { "bbb1", "bbb2" })
                        .AddCheck("ccc", Check, new string[] { "ccc1", "ccc1" })
                    )
                .Configure(app => app.UseHealthChecks("/healthcheck", options)))
            .Build()
            .Run();
        static Task ReportAsync(Microsoft.AspNetCore.Http.HttpContext content, HealthReport report)
        {
            content.Response.ContentType = "application/json";
            var settings = new JsonSerializerSettings();
            settings.Formatting = Formatting.Indented;
            settings.Converters.Add(new StringEnumConverter());
            return content.Response.WriteAsync(JsonConvert.SerializeObject(report, settings));
        }
        HealthCheckResult Check()
        {
            return (random.Next(1, 4)) switch
            {
                1 => HealthCheckResult.Unhealthy("Unavailable"),
                2 => HealthCheckResult.Degraded("Degraded"),
                _ => HealthCheckResult.Healthy("Normal")
            };
        }
    }
}

针对 Entity Framework Core 的健康检查

基于 DbContext 的健康检查

public class FooContext:DbContext
{
    public FooContext(DbContextOptions<FooContext> options) : base(options)
    {}
}
public class BarContext : DbContext
{
    public BarContext(DbContextOptions<BarContext> options) : base(options)
    {}
}

static void Main(string[] args)
{
    var options = new HealthCheckOptions
    {
        ResponseWriter = ReportAsync
    };
    Host.CreateDefaultBuilder()
        .ConfigureWebHostDefaults(builder => builder
            .ConfigureServices(svcs => svcs
                .AddDbContext<FooContext>(options => options.UseSqlServer("<Connection String>"))
                .AddDbContext<BarContext>(options => options.UseSqlServer("<Connection String>"))
                .AddHealthChecks()
                    .AddDbContextCheck<FooContext>()
                    .AddDbContextCheck<BarContext>()
                )
            .Configure(app => app.UseHealthChecks("/healthcheck", options)))
        .Build()
        .Run();
    static Task ReportAsync(Microsoft.AspNetCore.Http.HttpContext content, HealthReport report)
    {
        var builder = new StringBuilder();
        builder.AppendLine($"Status: {report.Status}");
        foreach (var name in report.Entries.Keys)
        {
            builder.AppendLine($"{name}:{report.Entries[name].Status}");
        }
        return content.Response.WriteAsync(builder.ToString());
    }

发布健康报告

var random = new Random();
var options = new HealthCheckOptions
{
    ResponseWriter = ReportAsync
};
Host.CreateDefaultBuilder()
    .ConfigureWebHostDefaults(builder => builder
        .ConfigureServices(svcs => svcs
            .AddHealthChecks()
                .AddCheck("aaa", Check)
                .AddCheck("bbb", Check)
                .AddCheck("ccc", Check)
                    .AddConsolePublisher()
                    .ConfigurePublisher(options =>
                        options.Period = TimeSpan.FromSeconds(5)))
            )
        .Configure(app => app.UseHealthChecks("/healthcheck", options)))
    .Build()
    .Run();
static Task ReportAsync(Microsoft.AspNetCore.Http.HttpContext content, HealthReport report)
{
    content.Response.ContentType = "application/json";
    var settings = new JsonSerializerSettings();
    settings.Formatting = Formatting.Indented;
    settings.Converters.Add(new StringEnumConverter());
    return content.Response.WriteAsync(JsonConvert.SerializeObject(report, settings));
}
HealthCheckResult Check()
{
    return (random.Next(1, 4)) switch
    {
        1 => HealthCheckResult.Unhealthy("Unavailable"),
        2 => HealthCheckResult.Degraded("Degraded"),
        _ => HealthCheckResult.Healthy("Normal")
    };
}

public static class Extensions
{
    public static IHealthChecksBuilder AddConsolePublisher(this IHealthChecksBuilder builder)
    {
        builder.Services.AddSingleton<IHealthCheckPublisher, ConsolePublisher>();
        return builder;
    }
    public static IHealthChecksBuilder ConfigurePublisher(this IHealthChecksBuilder builder, Action<HealthCheckPublisherOptions> configure)
    {
        builder.Services.Configure(configure);
        return builder;
    }
}

public class ConsolePublisher : IHealthCheckPublisher
{
    private readonly ObjectPool<StringBuilder> _stringBuilderPool;
    public ConsolePublisher(ObjectPoolProvider provider)
    {
        _stringBuilderPool = provider.CreateStringBuilderPool();
    }
    public Task PublishAsync(HealthReport report, CancellationToken cancellationToken)
    {
        cancellationToken.ThrowIfCancellationRequested();
        var builder = _stringBuilderPool.Get();
        try
        {
            builder.AppendLine($"Status: {report.Status}[{ DateTimeOffset.Now.ToString("yy-MM-dd hh:mm:ss")}]");
            foreach (var name in report.Entries.Keys)
            {
                builder.AppendLine($"    {name}: {report.Entries[name].Status}");
            }
            Console.WriteLine(builder);
            return Task.CompletedTask;
        }
        finally
        {
            _stringBuilderPool.Return(builder);
        }
    }
}

健康检查(UI)

static void LastPractice()
{
    var random = new Random();
    var options = new HealthCheckOptions
    {
        Predicate = _ => true,
        ResponseWriter = UIResponseWriter.WriteHealthCheckUIResponse//ReportAsync
    };
    var options2 = new HealthCheckOptions
    {
        ResponseWriter = UIResponseWriter.WriteHealthCheckUIResponse,
        Predicate = reg => reg.Name == "ccc"
    };
    Host.CreateDefaultBuilder()
        .ConfigureWebHostDefaults(builder => builder
            .ConfigureServices(svcs => svcs
                .AddHealthChecks()
                    .AddCheck("aaa", Check)
                    .AddCheck("bbb", Check)
                    .AddCheck("ccc", Check)
                        .AddConsolePublisher()
                        .ConfigurePublisher(option=>option.Period = TimeSpan.FromSeconds(5))
                )
            .Configure(app => {
                app.UseHealthChecks("/healthcheck", options);
                app.UseHealthChecks("/healthcheck2", options2);
            }))
        .Build()
        .Run();
    static Task ReportAsync(Microsoft.AspNetCore.Http.HttpContext content, HealthReport report)
    {
        content.Response.ContentType = "application/json";
        var settings = new JsonSerializerSettings();
        settings.Formatting = Formatting.Indented;
        settings.Converters.Add(new StringEnumConverter());
        return content.Response.WriteAsync(JsonConvert.SerializeObject(report, settings));
    }
    HealthCheckResult Check()
    {
        return (random.Next(1, 4)) switch
        {
            1 => HealthCheckResult.Unhealthy("Unavailable"),
            2 => HealthCheckResult.Degraded("Degraded"),
            _ => HealthCheckResult.Healthy("Normal")
        };
    }
}

创建一个项目名为 HealthDashboard 的 webApi 网站，添加健康面板 AspNetCore.HealthChecks.UI 以及 AspNetCore.HealthChecks.UI.InMemory.Storage 依赖包。注册 HealthCheck 健康面板的相关服务，并映射相关路径，默认通过 /healthchecks-ui 即可访问。

public class Startup
{
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }
    public IConfiguration Configuration { get; }
    public void ConfigureServices(IServiceCollection services)
    {
        services
            .AddHealthChecksUI()
            .AddInMemoryStorage();
    }
    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        app
            .UseRouting()
            .UseEndpoints(config =>
            {
                config.MapHealthChecksUI();
            });
    }
}

{
  "HealthChecksUI": {
    "HealthChecks": [
      {
        "Name": "IHealthCheckConsole",
        "Uri": "http://localhost:5000/healthcheck"
      },
      {
        "Name": "IHealthCheckConsole-Only-CCC",
        "Uri": "http://localhost:5000/healthcheck2"
      }
    ],
    "Webhooks": [
      {
        "Name": "Default",
        "Uri": "",
        "Payload": "{\"text\":\"The HealthCheck [[LIVENESS]] is failing with the error message: [[FAILURE]]. [[DESCRIPTIONS]]. <http://yourappstatus|Click here> to get more details.\",\"channel\":\"#general\",\"link_names\": 1,\"username\":\"monkey-bot\",\"icon_emoji\":\":monkey_face:\"}",
        "RestoredPayload": "{\"text\":\"The HealthCheck [[LIVENESS]] is recovered. All is up and running\",\"channel\":\"#general\",\"link_names\": 1,\"username\":\"monkey-bot\",\"icon_emoji\":\":monkey_face:\"}"
      }
    ],
    "EvaluationTimeinSeconds": 10,
    "MinimumSecondsBetweenFailureNotifications": 60
  }
}

HealthChecks

public void ConfigureServices(IServiceCollection services)
{
    services
        .AddHealthChecksUI(setup=> {
            setup.AddHealthCheckEndpoint("IHealthCheckConsole", "http://localhost:5000/healthcheck");
            setup.AddHealthCheckEndpoint("IHealthCheckConsole-Only-CCC", "http://localhost:5000/healthcheck2");
        })
        .AddInMemoryStorage();
}

Webhooks

public void ConfigureServices(IServiceCollection services)
{
    services
        .AddHealthChecksUI(setup=> {
            setup.AddHealthCheckEndpoint("IHealthCheckConsole", "http://localhost:5000/healthcheck");
            setup.AddHealthCheckEndpoint("IHealthCheckConsole-Only-CCC", "http://localhost:5000/healthcheck2");
            setup.AddWebhookNotification("Default", uri: "", payload: "{...}");
        })
        .AddInMemoryStorage();
}

EvaluationTimeinSeconds

MinimumSecondsBetweenFailureNotifications

UI自定义样式表

添加示例文件以及样式

dotnet.css 样式如下

:root {
    --primaryColor: #68217a;
    --secondaryColor: #f4f4f4;
    --bgMenuActive: #8e47a0;
    --bgButton: #68217a;
    --logoImageUrl: url('../../logo.png');
    --bgAside: var(--primaryColor);
}

Startup.cs

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    app.UseStaticFiles();
    app
        .UseRouting()
        .UseEndpoints(config =>
        {
            config.MapHealthChecksUI(setup=> {
                setup.AddCustomStylesheet("wwwroot\\dotnet.css");
            });
        });
}

HealthCheck 与 Kubernetes

https://github.com/Xabaril/AspNetCore.Diagnostics.HealthChecks/blob/master/doc/k8s-operator.md