上一篇博文中，說明了怎么引進Prometheus到asp.net core項目中，因為是Demo，所以Prometheus和Grafana都是windows版本，本地執行的，生產環境上這些服務可以根據的公司的架構，放到適合的環境內，現在這些服務都支持跨平臺化和容器化。并且在上篇博客中展示的是http請求的基礎信息模板，本篇博客介紹自定義Prometheusr指標類型。

Prometheus有四種指標類型：Counter（計數器）、Gauge（儀表盤）、Histogram（直方圖）、Summary（摘要），如果對業務的指標進行收集展示，在項目中是侵入式編程的，如果項目使用Prometheus.net進行對接Permetheus，是通過該包中的靜態方法 Metrics.CreateCounter(),Metrics.CreateGauge(),Metrics.CreateSummary(),Metrics.CreateHistogram()來創建靜態指標收集器，完成對業務指標收集的。

我們先來看具體Demo。

1、Counter：計數器，只增不減

先設置個業務場景：比如做一個商城，有用戶注冊(/register)，下訂單(/order)，支付(/pay)，發貨(/ship)四個API，代碼如下：

using Microsoft.AspNetCore.Mvc; using Microsoft.Extensions.Logging; using PrometheusSample.Models; using PrometheusSample.Services; using System; using System.Threading.Tasks;namespace PrometheusSample.Controllers {[ApiController][Route("[controller]")]public class BusinessController : ControllerBase{private readonly ILogger<BusinessController> _logger;private readonly IOrderService _orderService;public BusinessController(ILogger<BusinessController> logger, IOrderService orderService){_orderService = orderService;_logger?=?logger;}/// <summary>/// 注冊/// </summary>/// <param name="username">用戶名</param>/// <returns></returns>[HttpPost("/register")]public async Task<IActionResult> RegisterUser([FromBody] User user){try{_logger.LogInformation("用戶注冊");var result = await _orderService.Register(user.UserName);if (result){return new JsonResult(new { Result = true });}else{return new JsonResult(new { Result = false });}}catch (Exception exc){_logger.LogCritical(exc, exc.Message);return new JsonResult(new { Result = false, Message = exc.Message });}}[HttpGet("/order")]public IActionResult Order(string orderno){try{_logger.LogInformation("下單");?????????????return?new?JsonResult(new?{?Result?=?true });}catch (Exception exc){_logger.LogCritical(exc, exc.Message);return new JsonResult(new{Result = false,Message = exc.Message});}}[HttpGet("/pay")]public IActionResult Pay(){try{_logger.LogInformation("支付");return new JsonResult(new { Result = true });}catch (Exception exc){_logger.LogCritical(exc, exc.Message);return new JsonResult(new { Result = false, Message = exc.Message });}}[HttpGet("/ship")]public IActionResult Ship(){try{_logger.LogInformation("發貨");return new JsonResult(new { Result = true });}catch (Exception exc){_logger.LogCritical(exc, exc.Message);return new JsonResult(new { Result = false, Message = exc.Message });}}} }

上面是基本的業務Controller，為了降低依賴，我們的業務指標收集統一到一個中間件中去收集，中間件根據請求的url，和返回的數據結果數據進行業務指標數據的收集，當然也可以引入action過濾器或MediatR等中介者模式的組件來隔離業務邏輯的開發與監控數據的采集。

本例是用中間件的方式，首先定義一個靜態的指標收集器：

public class MetricsHub{private static Dictionary<string, Counter> _counterDictionary = new Dictionary<string, Counter>();public?Counter?GetCounter(string?key){if (_counterDictionary.ContainsKey(key)){return _counterDictionary[key];}else{return null;}}public void AddCounter(string key, Counter counter){_counterDictionary.Add(key, counter);}}

定義中間件BusinessMetricsMiddleware

using Microsoft.AspNetCore.Http; using PrometheusSample.Models; using System.IO; using System.Threading.Tasks;namespace PrometheusSample.Middlewares {/// <summary>/// 請求記錄中間件/// </summary>public class BusinessMetricsMiddleware{private?readonly?RequestDelegate?_next;public BusinessMetricsMiddleware(RequestDelegate next){_next = next;}public async Task InvokeAsync(HttpContext context, MetricsHub metricsHub){var originalBody = context.Response.Body;try{using (var memStream = new MemoryStream()){//從管理返回的Response中取出返回數據，根據返回值進行監控指標計數context.Response.Body = memStream;await _next(context);memStream.Position = 0;string responseBody = new StreamReader(memStream).ReadToEnd();memStream.Position = 0;await memStream.CopyToAsync(originalBody);if (metricsHub.GetCounter(context.Request.Path) != null || metricsHub.GetGauge(context.Request.Path) != null){//這里約定所有action返回值是一個APIResult類型var result = System.Text.Json.JsonSerializer.Deserialize<APIResult>(responseBody, new System.Text.Json.JsonSerializerOptions { PropertyNameCaseInsensitive = true });if (result != null && result.Result){//獲取到Countervar counter = metricsHub.GetCounter(context.Request.Path);if (counter != null){//計數counter.Inc();}}}}}finally{context.Response.Body = originalBody;}}} }

中間件中，只要action請求返回的Result為true，就會計數，這樣做的前提條件是業務返回值有統一約定；但每個action返回不可能都一樣的，如果有特例，可以用action過濾器或中介者模式組件來對應。

再看一下Starup中是怎么配置這個中間件的：

using Microsoft.AspNetCore.Builder; using Microsoft.AspNetCore.Hosting; using Microsoft.AspNetCore.Mvc; using Microsoft.Extensions.Configuration; using Microsoft.Extensions.DependencyInjection; using Microsoft.Extensions.Hosting; using Microsoft.Extensions.Logging; using Microsoft.OpenApi.Models; using Prometheus; using PrometheusSample.Middlewares; using PrometheusSample.Services; using System; using System.Collections.Generic; using System.Linq; using System.Threading.Tasks;namespace PrometheusSample {public class Startup{public Startup(IConfiguration configuration){Configuration = configuration;}public?IConfiguration?Configuration?{?get;?}public void ConfigureServices(IServiceCollection services){MetricsHandle(services);services.AddScoped<IOrderService, OrderService>();services.AddControllers();services.AddSwaggerGen(c =>{c.SwaggerDoc("v1", new OpenApiInfo { Title = "PrometheusSample", Version = "v1" });});}public void Configure(IApplicationBuilder app, IWebHostEnvironment env){if (env.IsDevelopment()){app.UseDeveloperExceptionPage();app.UseSwagger();app.UseSwaggerUI(c => c.SwaggerEndpoint("/swagger/v1/swagger.json", "PrometheusSample v1"));}app.UseRouting();//http請求的中間件app.UseHttpMetrics();app.UseAuthorization();//自定義業務跟蹤app.UseBusinessMetrics();app.UseEndpoints(endpoints =>{//映射監控地址為 /metricsendpoints.MapMetrics();endpoints.MapControllers();});}/// <summary>/// 處理監控事項/// </summary>/// <param name="services"></param>void MetricsHandle(IServiceCollection services){var metricsHub = new MetricsHub();//countermetricsHub.AddCounter("/register", Metrics.CreateCounter("business_register_user", "注冊用戶數。"));metricsHub.AddCounter("/order", Metrics.CreateCounter("business_order_total", "下單總數。"));metricsHub.AddCounter("/pay", Metrics.CreateCounter("business_pay_total", "支付總數。"));metricsHub.AddCounter("/ship", Metrics.CreateCounter("business_ship_total", "發貨總數。"));services.AddSingleton(metricsHub);}} }

MetricsHandle中，我們添加了四個action，分別對應的四個計數器，這樣，當這四個url有請求，并且返回值中的result=true時，就會往對應的計數器上計數。

這樣數據收集好了，現在開始在Grafana中配置顯示的圖表了：

訂單各狀態總數配置：

訂單各狀態30秒內數量跟蹤折線

最后的運行結果是：

總結實現自定義業務計數器步驟：

1、分析業務，規劃好監控跟蹤指標

2、定義指標收集器

3、侵入編程(盡量在開發時分離業務實現與監控指票的收集代碼)收集指標

4、開發grafana展示模板，完成展示

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