asp.net core監控—引入Prometheus（四）

上一篇博文中說到Prometheus有四種指標類型：Counter（計數器）、Gauge（儀表盤）、Histogram（直方圖）、Summary（摘要），而且咱們作了一個Counter的Demo，接下來看看Histogram。
Histogram：直方圖
直方圖，維基百科的定義：是一種對數據分佈狀況的圖形表示，是一種二維統計圖表，它的兩個座標分別是統計樣本和該樣本對應的某個屬性的度量，以長條圖（bar）的形式具體表現。由於直方圖的長度及寬度很適合用來表現數量上的變化，因此較容易解讀差別小的數值。仍是拿上一篇的Sample來講明，假如每一個訂單都有一個金額，在order時在返回值{result=true,data=1000}的data屬性中返回，這裏，咱們就能夠用直方圖來收集這個金額，因爲訂單的金額不同，咱們就能夠用直方圖來展現必定範圍金額內訂單的數據，監控出必定金額範圍內的訂單比例了。就是說在必定數量的訂單裏，少於1000元的有多少個訂單，少於2000元有多少個訂單，少於3000元的有多少個訂單……
首先，咱們得修改BusinessController中Order Action的業務邏輯，把訂單金額做爲返回值：

[HttpGet("/order")]
public IActionResult Order(string orderno)
{
    try
    {
        _logger.LogInformation("下單");
        //返回訂單金額             
        var random = new Random();
        return new JsonResult(new { Result = true, data = random.Next(1, 8000) });
    }
    catch (Exception exc)
    {
        _logger.LogCritical(exc, exc.Message);
        return new JsonResult(new { Result = false, Message = exc.Message });
    }
}

這裏的金額爲了方便demo，是隨機生成一個1到8000的隨機數。
須要在MetricsHub.cs中添加Histogram類型的指標收集集合：

using Prometheus;
using System.Collections.Generic;
namespace PrometheusSample.Middlewares
{ 
    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>>(); 
        private static Dictionary<string, Histogram> _histogramDictionary = new Dictionary<string, Histogram>(); 
        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 Histogram GetHistogram(string key) 
        {
            if (_histogramDictionary.ContainsKey(key))
            {
                return _histogramDictionary[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);
        } 
        public void AddHistogram(string key, Histogram histogram)
        { 
            _histogramDictionary.Add(key, histogram); 
        } 
    }
}

接下來就要在BusinessMetricsMiddleware的中間件中添加處理Histogram指標的代碼了：

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)
                    {
                        //這裏約定全部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)
                            {
                                //存在增長指標+就Inc 
                                if (gauges.ContainsKey("+"))
                                {
                                    gauges["+"].Inc();
                                }
                                //存在減小指標-就Dec              
                                if (gauges.ContainsKey("-")) { gauges["-"].Dec(); }
                            }
                            var histogram = metricsHub.GetHistogram(context.Request.Path); if (histogram != null)
                            {
                                var parseResult = int.TryParse(result.Data.ToString(), out int i);
                                if (parseResult)
                                {
                                    histogram.Observe(i);
                                }
                            }
                        }

                    }
                }
            }
            finally
            {
                context.Response.Body = originalBody;
            }
        }
    }
}

再就是在Starsup中配置對應url的Histogram參數了：

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請求的中間件        
            app.UseHttpMetrics();
            app.UseAuthorization();
            //自定義業務跟蹤       
            app.UseBusinessMetrics();
            app.UseEndpoints(endpoints =>
            {
                //映射監控地址爲  /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。"));
            //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", "當前發貨數據。");
            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 } });
            //histogram                   
            var orderHistogram = Metrics.CreateHistogram("business_order_histogram", "訂單直方圖。",
                new HistogramConfiguration
                {
                    Buckets = Histogram.LinearBuckets(start: 1000, width: 1000, count: 5)
                }); metricsHub.AddHistogram("/order", orderHistogram);
            services.AddSingleton(metricsHub);
        }
    }
}

Histogram.LinearBuckets(start: 1000, width: 1000, count: 5)是金額從1000開始，每1000爲一個臺階，一共6個臺階：0~1000，1001~2000，2001~3000，3001~4000，4001~5000，還有一個是大於5000的。
最後一步，就是打開Grafana來配置展現圖表了。
訂單金額分佈圖

訂單比例分佈圖

圖中histogram_quantile(0.80, sum(rate(business_order_histogram_bucket[5m])) by (le))的意思是「80%的訂單金額小於等於這個值」5分鐘內的值。
最終展現結果：

聰明的你必定發現，這篇博文與上一篇一模一樣，是的，只是監控指標展現類型不一樣而以。