1. 项目创建与基础设置

创建新项目

首先，创建一个新的 ASP.NET Core Web API 项目：

dotnet new webapi -n HealthCheckDemo
cd HealthCheckDemo

添加必要的 NuGet 包

添加健康检查相关的 NuGet 包：

dotnet add package Microsoft.AspNetCore.Diagnostics.HealthChecks
dotnet add package AspNetCore.HealthChecks.SqlServer  # 用于数据库健康检查
dotnet add package AspNetCore.HealthChecks.Redis     # 用于 Redis 健康检查

2. 健康检查原理解析

在深入代码之前，让我们先理解健康检查的核心概念：

健康检查服务：ASP.NET Core 提供了一个框架，用于报告应用程序及其依赖组件的健康状态
检查类型：
- 存活检查 (Liveness)：应用程序是否正在运行
- 就绪检查 (Readiness)：应用程序是否准备好处理请求
- 依赖检查：外部依赖（数据库、缓存等）是否可用
响应格式：健康检查端点返回一个 JSON 对象，包含整体状态和各个检查的详细结果

3. 完整代码实现

Program.cs 完整代码

using Microsoft.AspNetCore.Diagnostics.HealthChecks;
using Microsoft.Extensions.Diagnostics.HealthChecks;
using System.Text.Json;
using System.Text.Json.Serialization;var builder = WebApplication.CreateBuilder(args);// 添加服务到容器
builder.Services.AddControllers();
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();// 1. 注册健康检查服务
builder.Services.AddHealthChecks()// 2. 添加一个简单的存活检查（总是健康）.AddCheck("self", () => HealthCheckResult.Healthy("Application is running"), tags: new[] { "live" })// 3. 添加数据库健康检查（模拟）.AddCheck("database", () => {// 模拟数据库检查var isHealthy = CheckDatabaseConnection();return isHealthy ? HealthCheckResult.Healthy("Database connection is OK") : HealthCheckResult.Unhealthy("Database connection failed");}, tags: new[] { "ready", "database" })// 4. 添加 Redis 健康检查（模拟）.AddCheck("redis", () => {// 模拟 Redis 检查var isHealthy = CheckRedisConnection();return isHealthy ? HealthCheckResult.Healthy("Redis connection is OK") : HealthCheckResult.Unhealthy("Redis connection failed");}, tags: new[] { "ready", "redis" });// 模拟数据库连接检查方法
bool CheckDatabaseConnection()
{// 在实际应用中，这里会尝试连接到真实数据库// 这里我们模拟90%的成功率return new Random().NextDouble() > 0.1;
}// 模拟 Redis 连接检查方法
bool CheckRedisConnection()
{// 在实际应用中，这里会尝试连接到真实 Redis// 这里我们模拟80%的成功率return new Random().NextDouble() > 0.2;
}var app = builder.Build();// 配置 HTTP 请求管道
if (app.Environment.IsDevelopment())
{app.UseSwagger();app.UseSwaggerUI();
}app.UseHttpsRedirection();
app.UseAuthentication();
app.UseAuthorization();
app.MapControllers();// 5. 配置健康检查端点// 综合健康检查端点（包含所有检查）
app.MapHealthChecks("/health", new HealthCheckOptions
{// 自定义响应格式ResponseWriter = async (context, report) =>{context.Response.ContentType = "application/json";var response = new{status = report.Status.ToString(),totalDuration = report.TotalDuration.ToString(),checks = report.Entries.Select(e => new{name = e.Key,status = e.Value.Status.ToString(),description = e.Value.Description,duration = e.Value.Duration.ToString()})};await context.Response.WriteAsync(JsonSerializer.Serialize(response, new JsonSerializerOptions { WriteIndented = true }));}
});// 存活检查端点（只包含快速的基本检查）
app.MapHealthChecks("/health/live", new HealthCheckOptions
{Predicate = check => check.Tags.Contains("live"),ResponseWriter = WriteHealthCheckResponse
});// 就绪检查端点（包含所有依赖检查）
app.MapHealthChecks("/health/ready", new HealthCheckOptions
{Predicate = check => check.Tags.Contains("ready"),ResponseWriter = WriteHealthCheckResponse
});// 健康检查响应写入器
async Task WriteHealthCheckResponse(HttpContext context, HealthReport report)
{context.Response.ContentType = "application/json";var result = JsonSerializer.Serialize(new{status = report.Status.ToString(),checks = report.Entries.Select(e => new{name = e.Key,status = e.Value.Status.ToString()})});await context.Response.WriteAsync(result);
}app.Run();

添加一个示例控制器

创建 Controllers/TestController.cs：

using Microsoft.AspNetCore.Mvc;namespace HealthCheckDemo.Controllers;[ApiController]
[Route("[controller]")]
public class TestController : ControllerBase
{private static int _requestCount = 0;[HttpGet]public IActionResult Get(){_requestCount++;// 每10个请求模拟一次故障if (_requestCount % 10 == 0){return StatusCode(500, "Simulated server error");}return Ok($"Request #{_requestCount}: Hello from TestController!");}
}

4. 测试健康检查

启动应用程序

dotnet run

测试不同健康检查端点

综合健康检查（所有检查）：
```
curl -k https://localhost:7003/health
```

存活检查（只检查应用本身）：

curl -k https://localhost:7003/health/live

就绪检查（检查应用和所有依赖）：
```
curl -k https://localhost:7003/health/ready
```

示例响应

成功响应：

{"status": "Healthy","totalDuration": "00:00:00.1024567","checks": [{"name": "self","status": "Healthy","description": "Application is running","duration": "00:00:00.0000862"},{"name": "database","status": "Healthy","description": "Database connection is OK","duration": "00:00:00.1001234"},{"name": "redis","status": "Healthy","description": "Redis connection is OK","duration": "00:00:00.1002341"}]
}

失败响应：

{"status": "Unhealthy","totalDuration": "00:00:00.2034567","checks": [{"name": "self","status": "Healthy","description": "Application is running","duration": "00:00:00.0000762"},{"name": "database","status": "Unhealthy","description": "Database connection failed","duration": "00:00:00.2001234"},{"name": "redis","status": "Healthy","description": "Redis connection is OK","duration": "00:00:00.2002341"}]
}

5. 与容器编排系统集成

创建 Dockerfile

FROM mcr.microsoft.com/dotnet/aspnet:8.0 AS base
WORKDIR /app
EXPOSE 80
EXPOSE 443FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build
WORKDIR /src
COPY ["HealthCheckDemo.csproj", "."]
RUN dotnet restore "HealthCheckDemo.csproj"
COPY . .
RUN dotnet build "HealthCheckDemo.csproj" -c Release -o /app/buildFROM build AS publish
RUN dotnet publish "HealthCheckDemo.csproj" -c Release -o /app/publishFROM base AS final
WORKDIR /app
COPY --from=publish /app/publish .
ENTRYPOINT ["dotnet", "HealthCheckDemo.dll"]

Kubernetes 部署配置

创建 deployment.yaml：

apiVersion: apps/v1
kind: Deployment
metadata:name: healthcheck-demo
spec:replicas: 3selector:matchLabels:app: healthcheck-demotemplate:metadata:labels:app: healthcheck-demospec:containers:- name: healthcheck-demoimage: healthcheck-demo:latestports:- containerPort: 80# 存活探针 - 检查应用是否正在运行livenessProbe:httpGet:path: /health/liveport: 80initialDelaySeconds: 10periodSeconds: 10timeoutSeconds: 5failureThreshold: 3# 就绪探针 - 检查应用是否准备好接收流量readinessProbe:httpGet:path: /health/readyport: 80initialDelaySeconds: 5periodSeconds: 5timeoutSeconds: 3failureThreshold: 1# 启动探针 - 检查应用是否已启动startupProbe:httpGet:path: /health/liveport: 80initialDelaySeconds: 10periodSeconds: 10failureThreshold: 30
---
apiVersion: v1
kind: Service
metadata:name: healthcheck-demo-service
spec:selector:app: healthcheck-demoports:- protocol: TCPport: 80targetPort: 80type: LoadBalancer

6. 高级功能：健康检查 UI

添加健康检查 UI

dotnet add package AspNetCore.HealthChecks.UI
dotnet add package AspNetCore.HealthChecks.UI.Client
dotnet add package AspNetCore.HealthChecks.UI.InMemory.Storage

更新 Program.cs

在 builder.Services.AddHealthChecks() 后添加：

// 添加健康检查 UI 服务
builder.Services.AddHealthChecksUI(setup =>
{setup.AddHealthCheckEndpoint("API", "/health");setup.SetEvaluationTimeInSeconds(60); // 每60秒检查一次setup.SetMinimumSecondsBetweenFailureNotifications(60); // 失败通知最小间隔
})
.AddInMemoryStorage();

在端点映射部分添加：

// 健康检查 UI 端点
app.MapHealthChecksUI(setup => 
{setup.UIPath = "/healthchecks-ui";setup.ApiPath = "/healthchecks-api";
});

现在您可以访问 /healthchecks-ui 查看健康检查的可视化界面。

7. 实际数据库健康检查

替换模拟的数据库检查为真实的 SQL Server 检查：

// 在 Program.cs 的顶部添加
using Microsoft.Data.SqlClient;// 替换模拟的数据库检查
.AddSqlServer(connectionString: builder.Configuration.GetConnectionString("DefaultConnection"),healthQuery: "SELECT 1;", // 简单的健康检查查询name: "sql",failureStatus: HealthStatus.Unhealthy,tags: new[] { "ready", "database" }
)

在 appsettings.json 中添加连接字符串：

{"ConnectionStrings": {"DefaultConnection": "Server=localhost;Database=master;User Id=sa;Password=YourPassword123;TrustServerCertificate=true;"},// 其他配置...
}