Prometheus

random-metrics.go

package main

import (
	"log"
	"math/rand"
	"net/http"
	"time"

	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"
)

var (
	httpReqs = prometheus.NewCounterVec(
		prometheus.CounterOpts{
			Name: "user_http_requests_total",
			Help: "How many HTTP requests processed, partitioned by status code and HTTP method.",
		},
		[]string{"code", "method"},
	)

	method = []string{"GET", "GET", "POST", "GET", "GET", "GET", "GET", "POST"}
	code   = []string{"503", "200", "200", "200", "200", "404", "200", "200"}
)

func init() {
	// Metrics have to be registered to be exposed:
	prometheus.MustRegister(httpReqs)
}

func generateRequest() <-chan [2]string {
	ticker := time.NewTicker(2 * time.Second)

	metrics := make(chan [2]string)
	go func() {
		for range ticker.C {
			request := [2]string{
				code[rand.Intn(len(code))],
				method[rand.Intn(len(method))],
			}
			metrics <- request
		}
	}()
	return metrics
}

func main() {
	httpReqs.WithLabelValues("404", "POST").Add(42)

	// m := httpReqs.withLabelValue("200", "GET")
	metrics := generateRequest()
	go func() {
		for {
			select {
			case request := <-metrics:
				httpReqs.WithLabelValues(request[0], request[1]).Inc()
				log.Println(request)
			}
		}
	}()

	http.Handle("/metrics", promhttp.Handler())
	log.Fatal(http.ListenAndServe(":8080", nil))
}