【Go】监控指标的书写

文章目录

我们知道，我们很多时候是需要知道我们的一个程序的运行状态的，那这个时候就是需要用到监控。这里，我们使用的监控是 Prometheus ，那我们的这个监控的指标怎么写呢，笔者找了点资料，写了几个简单的 Demo。这个 Demo 一定是存在不足的，大家可以评论告知。

如何利用Prometheus监控你的应用

引包

import (
	. "flag"
	"github.com/gin-gonic/gin"
	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	"log"
	"math/rand"
	"strconv"
	"sync"
	"time"
)

指标的定义

totalCounterVec = prometheus.NewCounterVec(
		prometheus.CounterOpts{
			Namespace: "worker",
			Subsystem: "jobs",
			Name:      "processed_total",
			Help:      "Total number of jobs processed by the workers",
		},
		[]string{"worker_id", "type"},
	)

	http_request_total = prometheus.NewCounter(
		prometheus.CounterOpts{
			Name: "http_request_total" ,
			Namespace: "prometheus_front_server",
			Help: "The total number of processed http requests",
		})

	inflightCounterVec = prometheus.NewGaugeVec(
		prometheus.GaugeOpts{
			Namespace: "worker",
			Subsystem: "jobs",
			Name:      "inflight",
			Help:      "Number of jobs inflight",
		},
		[]string{"type"},
	)

	processingTimeVec = prometheus.NewHistogramVec(
		prometheus.HistogramOpts{
			Namespace: "worker",
			Subsystem: "jobs",
			Name:      "process_time_seconds",
			Help:      "Amount of time spent processing jobs",
		},
		[]string{"worker_id", "type"},
	)

先来看这三个 vec 的指标:

// track the total number of jobs processed by the worker
totalCounterVec.WithLabelValues(strconv.FormatInt(int64(workerID), 10), job.Type).Inc()
// decrement the inflight tracker
inflightCounterVec.WithLabelValues(job.Type).Dec()
processingTimeVec.WithLabelValues(strconv.FormatInt(int64(workerID), 10), job.Type).Observe(time.Now().Sub(startTime).Seconds())

再来看这个普通的 http_request_total:

func test(ctx *gin.Context){
	http_request_total.Inc()
}

现在，我们再来看这个主函数的写法:

	engine := gin.New()
	engine.GET("/test" , test)
	engine.GET("/metrics" , prometheusHttp)
	engine.Run("0.0.0.0:9010")

prometheusHttp 里面的代码如下:

// 这里我是不是很清楚的，因为我觉得这个 gin 框架应该是可以不这么做
func prometheusHttp(ctx *gin.Context){
	handler := promhttp.Handler()
	handler.ServeHTTP(ctx.Writer , ctx.Request)
}

整理

NewCounter

我们利用promauto包提供的 NewCounter 方法定义了一个 Counter 类型的监控指标，只需要填充名字以及帮助信息，该指标就创建完成了。需要注意的是，Counter 类型数据的名字要尽量以 _total 作为后缀。否则当 Prometheus 与其他系统集成时，可能会出现指标无法识别的问题。每当有请求访问根目录时，该指标就会调用 Inc() 方法加一，当然，我们也可以调用 Add()方法累加任意的非负数。

NewGauge

监控累积的请求处理显然还是不够的，通常我们还想知道当前正在处理的请求的数量。Prometheus中的Gauge类型数据，与Counter不同，它既能增大也能变小。将正在处理的请求数量定义为Gauge类型是合适的。e.g:

	http_request_in_flight = prometheus.NewGauge(
		prometheus.GaugeOpts{
			Namespace: "prometheus_front_server" ,
			Name:	"http_request_in_flight",
			Help:	"Current number of http requests in flight",
		},
    )
    
func test2(ctx *gin.Context){
	http_request_in_flight.Inc()
	defer http_request_in_flight.Desc()
	http_request_total.Inc()
}

Gauge和Counter类型的数据操作起来的差别并不大，唯一的区别是Gauge支持Dec()或者Sub()方法减小指标的值。

NewHistogram

对于一个网络服务来说，能够知道它的平均时延是重要的，不过很多时候我们更想知道响应时间的分布状况。Prometheus 中的 Histogram 类型就对此类需求提供了很好的支持。e.g:

	http_request_duration_seconds = prometheus.NewHistogram(
		prometheus.HistogramOpts{
			Namespace:   "prometheus_front_server",
			Subsystem:   "jobs",
			Name:        "http_request_duration_seconds",
			Help:        "Histogram of lantencies for HTTP requests",
			ConstLabels: nil,
			Buckets:     nil,
        })
        
    // 测试
 	http_request_in_flight.Inc()
	defer http_request_in_flight.Desc()
	http_request_total.Inc()

	time.Sleep(time.Duration(rand.Intn(1000)) * time.Millisecond)
	http_request_duration_seconds.Observe(time.Since(time.Now()).Seconds())

Summary

这个和 Histogram 是一样的用法

NewCounterVec

不过，有的时候，我们可能希望从更多的特征维度去衡量一个指标。例如，对于接收到的HTTP请求的数目，我们可能希望知道具体到每个路径接收到的请求数目。假设当前能够访问 / 和 /foo 目录，显然定义两个不同的 Counter，比如 http_request_root_total和 http_request_foo_total，并不是一个很好的方法。一方面扩展性比较差：如果定义更多的访问路径就需要创建更多新的监控指标，同时，我们定义的特征维度往往不止一个，可能我们想知道某个路径且返回码为XXX的请求数目是多少，这种方法就无能为力了；另一方面，PromQL也无法很好地对这些指标进行聚合分析。

Prometheus对于此类问题的方法是为指标的每个特征维度定义一个label，一个label本质上就是一组键值对。一个指标可以和多个label相关联，而一个指标和一组具体的label可以唯一确定一条时间序列。对于上述分别统计每条路径的请求数目的问题，标准的Prometheus的解决方法如下：e.g:

totalCounterVec = prometheus.NewCounterVec(
		prometheus.CounterOpts{
			Namespace: "worker",
			Subsystem: "jobs",
			Name:      "processed_total",
			Help:      "Total number of jobs processed by the workers",
        },
        // []string{"path"}
		[]string{"worker_id", "type"},
	)

这里，我们是根据这个 work_id ，和当前的类型 type 来做的这个维度：

totalCounterVec.WithLabelValues(workerId, "type").Inc()

后面的几个 Vec 也是和这个的用法一样的。

这里的介绍就这么多，给一个我测试用的 Demo 的源码:

package main

import (
	. "flag"
	"github.com/gin-gonic/gin"
	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	"log"
	"math/rand"
	"strconv"
	"sync"
	"time"
)

// Package: awesomeProject
// Version: 1.0
//
// Created by SunYang on 2020/5/15 11:14

var (
	types   = []string{"emai", "deactivation", "activation", "transaction", "customer_renew", "order_processed"}
	workers = 0

	totalCounterVec = prometheus.NewCounterVec(
		prometheus.CounterOpts{
			Namespace: "worker",
			Subsystem: "jobs",
			Name:      "processed_total",
			Help:      "Total number of jobs processed by the workers",
		},
		[]string{"worker_id", "type"},
	)

	http_request_total = prometheus.NewCounter(
		prometheus.CounterOpts{
			Name: "http_request_total" ,
			Namespace: "prometheus_front_server",
			Help: "The total number of processed http requests",
		})

	http_request_in_flight = prometheus.NewGauge(
		prometheus.GaugeOpts{
			Namespace: "prometheus_front_server" ,
			Name:	"http_request_in_flight",
			Help:	"Current number of http requests in flight",
		},
	)

	http_request_duration_seconds = prometheus.NewHistogram(
		prometheus.HistogramOpts{
			Namespace:   "prometheus_front_server",
			Subsystem:   "jobs",
			Name:        "http_request_duration_seconds",
			Help:        "Histogram of lantencies for HTTP requests",
			ConstLabels: nil,
			Buckets:     nil,
		})

	inflightCounterVec = prometheus.NewGaugeVec(
		prometheus.GaugeOpts{
			Namespace: "worker",
			Subsystem: "jobs",
			Name:      "inflight",
			Help:      "Number of jobs inflight",
		},
		[]string{"type"},
	)

	processingTimeVec = prometheus.NewHistogramVec(
		prometheus.HistogramOpts{
			Namespace: "worker",
			Subsystem: "jobs",
			Name:      "process_time_seconds",
			Help:      "Amount of time spent processing jobs",
		},
		[]string{"worker_id", "type"},
	)
)

func init() {
	IntVar(&workers, "workers", 10, "Number of workers to use")
}
func getType() string {
	return types[rand.Int()%len(types)]
}

type Job struct {
	Type  string
	Sleep time.Duration
}

func main() {
	Parse()
	// 开始注册
	prometheus.MustRegister(
		totalCounterVec,
		http_request_total,
		http_request_in_flight,
		http_request_duration_seconds,
		inflightCounterVec,
		processingTimeVec)

	// create a channel with a 10,000 Job buffer
	jobsChannel := make(chan *Job, 10000)

	go startJobProcess(jobsChannel)

	engine := gin.New()
	engine.GET("/test" , test)
	engine.GET("/test2" , test2)
	engine.GET("/metrics" , prometheusHttp)
	engine.Run("0.0.0.0:9010")

}

func prometheusHttp(ctx *gin.Context){
	handler := promhttp.Handler()
	handler.ServeHTTP(ctx.Writer , ctx.Request)
}

func test(ctx *gin.Context){
	http_request_total.Inc()
}

func test2(ctx *gin.Context){
	http_request_in_flight.Inc()
	defer http_request_in_flight.Desc()
	http_request_total.Inc()

	time.Sleep(time.Duration(rand.Intn(1000)) * time.Millisecond)
	http_request_duration_seconds.Observe(time.Since(time.Now()).Seconds())
}

func startJobProcess(jobs <-chan *Job) {
	log.Printf("[INFO] starting %d workers\n", workers)
	wait := sync.WaitGroup{}
	// notify the sync group we need to wait for 10 goroutines
	wait.Add(workers)

	// start 10 works
	for i := 0; i < workers; i++ {
		go func(workerID int) {
			// start the worker
			startWorker(workerID, jobs)
			wait.Done()
		}(i)
	}
	wait.Wait()
}

func startWorker(workerID int, jobs <-chan *Job) {
	for {
		select {
		// read from the job channel
		case job := <-jobs:
			startTime := time.Now()
			// fake processing the request
			time.Sleep(job.Sleep)
			log.Printf("[%d][%s] Processed job in %0.3f seconds", workerID, job.Type, time.Now().Sub(startTime).Seconds())
			// track the total number of jobs processed by the worker
			totalCounterVec.WithLabelValues(strconv.FormatInt(int64(workerID), 10), job.Type).Inc()
			// decrement the inflight tracker
			inflightCounterVec.WithLabelValues(job.Type).Dec()
			processingTimeVec.WithLabelValues(strconv.FormatInt(int64(workerID), 10), job.Type).Observe(time.Now().Sub(startTime).Seconds())
		}
	}
}

func createJobs(jobs chan<- *Job) {
	for {
		// create a random job
		job := makeJob()
		// track the job in the inflight tracker
		inflightCounterVec.WithLabelValues(job.Type).Inc()
		// send the job down the channel
		jobs <- job
		// don't pile up too quickly
		time.Sleep(5 * time.Millisecond)
	}
}
func makeJob() *Job {
	return &Job{
		Type:  getType(),
		Sleep: time.Duration(rand.Int()%100+10) * time.Millisecond,
	}
}

【Go】监控指标的书写

文章目录

引包

指标的定义

整理

NewCounter

NewGauge

NewHistogram

Summary

NewCounterVec

工作中用到的脚本合集

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