asp.net core監控—引入Prometheus(三)

桂素偉發表於2022-01-28

  上一篇博文中說到Prometheus有四種指標型別:Counter(計數器)、Gauge(儀表盤)、Histogram(直方圖)、Summary(摘要),並且我們做了一個Counter的Demo,接下來看看Gauge。

2、Gauge:儀表盤,有增有減

  這個指標非常像汽車的車速表,指標是在一定範圍內有增有減的。下面我們接著上一篇博文的Sample來說,現在需要實時監控處在下“單完成”,“支付完成”,“發貨完成”的單據資料,和各三種狀態的佔比;我們知道一個訂單在一個時刻只能是一種狀態,我們可以在下單時增加計數order的指標,但當訂單從order轉到pay狀態後,pay指標會增加,同時order指標會減少,這個場景就會用上了Gauge了。

  有了這個思路,我們可以上手程式碼了,BusinessController的程式碼不變(因為我們實現了業務邏輯程式碼和監控資料指標採集分離),這裡我們需要在MetricsHub.cs中新增Gauge型別的指標收集集合:

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

  因為在上面分析中,我們一個動作,比如pay時,會觸發兩個指標的改變,order指標減少,pay指標增加,所以Gauge是一個Dictionary<string, Dictionary<string, Gauge>>型別,內部的字典存放減少和增加的Gauge的監控指標物件。

  接下來就要在BusinessMetricsMiddleware的中介軟體中新增處理Gauge指標增加減少的程式碼了:

using Microsoft.AspNetCore.Http;
using PrometheusSample.Models;
using System.IO;
using System.Threading.Tasks;

namespace PrometheusSample.Middlewares
{
    /// <summary>
    /// 請求記錄中介軟體
    /// </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中取出返回資料,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)
                    {
                        //這裡約定所有action返回值是一個APIResult型別
                        var result = System.Text.Json.JsonSerializer.Deserialize<APIResult>(responseBody, new System.Text.Json.JsonSerializerOptions { PropertyNameCaseInsensitive = true });
                        if (result != null && result.Result)
                        {
                            //獲取到Counter
                            var counter = metricsHub.GetCounter(context.Request.Path);
                            if (counter != null)
                            {
                                //計數
                                counter.Inc();
                            }

                            var gauges = metricsHub.GetGauge(context.Request.Path);
                            if (gauges != null)
                            {
                                //存在增加指標+就Inc
                                if (gauges.ContainsKey("+"))
                                {
                                    gauges["+"].Inc();
                                } 
                                //存在減少指標-就Dec
                                if (gauges.ContainsKey("-"))
                                {
                                    gauges["-"].Dec();
                                }
                            }
                        }
                    }
                }
            }
            finally
            {
                context.Response.Body = originalBody;
            }

        }
    }
}

  再就是在Starsup中配置對應url的Gauge引數了:

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.OpenApi.Models;
using Prometheus;
using PrometheusSample.Middlewares;
using PrometheusSample.Services;
using System.Collections.Generic;
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請求的中介軟體
            app.UseHttpMetrics();
            app.UseAuthorization();
            //自定義業務跟蹤
            app.UseBusinessMetrics();
            app.UseEndpoints(endpoints =>
            {
                //對映監控地址為  /metrics
                endpoints.MapMetrics();
                endpoints.MapControllers();
            });
        }
        /// <summary>
        /// 處理監控事項
        /// </summary>
        /// <param name="services"></param>
        void MetricsHandle(IServiceCollection services)
        {
            var metricsHub = new MetricsHub();
            //counter
            metricsHub.AddCounter("/register", Metrics.CreateCounter("business_register_user", "註冊使用者數。"));
            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。"));

            //gauge
            var orderGauge = Metrics.CreateGauge("business_order_count", "當前下單數量。");
            var payGauge = Metrics.CreateGauge("business_pay_count", "當前支付數量。");
            var shipGauge = Metrics.CreateGauge("business_ship_count", "當前發貨資料。");
            metricsHub.AddGauge("/order", new Dictionary<string, Gauge> {
                { "+", orderGauge}
            });
            metricsHub.AddGauge("/pay", new Dictionary<string, Gauge> {
                {"-",orderGauge},
                {"+",payGauge}
            });
            metricsHub.AddGauge("/ship", new Dictionary<string, Gauge> {
                {"+",shipGauge},
                {"-",payGauge}
            });
            services.AddSingleton(metricsHub);
        }
    }
}

  最後一步,就是開啟Grafana來配置展示圖表了

  訂單狀態資料儀表盤

 

 

   訂單狀態比例圖

 

 

   最終的展示結果

  上一篇中我們說過自定義業務計數器型別的步驟,其實儀盤的步驟也一樣

  1、分析業務,規劃好監控跟蹤指標

  2、定義指標收集器

  3、侵入程式設計(儘量在開發時分離業務實現與監控指票的收集程式碼)收集指標

  4、開發grafana展示模板,完成展示

 

  想要更快更方便的瞭解相關知識,可以關注微信公眾號 
 

 

 

相關文章