✨ add sample with prometheus metrics

Author: yuanyu90221

.dockerignore

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+bin
+mage-tools
+gg
+mage
+Taskfile.yml
+.gitignore
+.env
+prometheus
+grafana

.gitignore

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+# If you prefer the allow list template instead of the deny list, see community template:
+# https://github.com/github/gitignore/blob/main/community/Golang/Go.AllowList.gitignore
+#
+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+
+# Test binary, built with `go test -c`
+*.test
+
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out
+
+# Dependency directories (remove the comment below to include it)
+# vendor/
+
+# Go workspace file
+go.work
+go.work.sum
+
+# env file
+.env
+gg
+mage
+bin

Dockerfile

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+FROM golang:1.22.4-alpine AS build
+WORKDIR /app
+COPY go.mod ./
+COPY go.sum ./
+RUN go mod download && go mod verify
+COPY . ./
+RUN go build -o /server ./cmd/main.go
+
+FROM gcr.io/distroless/base-debian11
+WORKDIR /app
+COPY --from=build /server /server
+ENTRYPOINT [ "/server" ]

README.md

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+# golang-sample-with-prometheus
+
+This repository is to demo how to use prometheus to collect golang application data
+
+## logic
+```golang
+package application
+
+import (
+	"encoding/json"
+	"math/rand"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/leetcode-golang-classroom/golang-sample-with-prometheus/internal/config"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/collectors"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+type Device struct {
+	ID       int    `json:"id"`
+	Mac      string `json:"mac"`
+	Firmware string `json:"firmware"`
+}
+
+type registerDevicesHandler struct {
+	metrics *metrics
+}
+
+type metrics struct {
+	devices       prometheus.Gauge
+	info          *prometheus.GaugeVec
+	upgrades      *prometheus.CounterVec
+	duration      *prometheus.HistogramVec
+	loginDuration prometheus.Summary
+}
+
+var devices []Device
+var version string
+
+func init() {
+	version = config.AppConfig.Version
+	devices = []Device{
+		{1, "5F-33-CC-1F-43-82", "2.1.6"},
+		{2, "EF-2B-C4-F5-D6-34", "2.1.6"},
+	}
+}
+
+func (app *App) SetupMetricRoute() {
+	reg := prometheus.NewRegistry()
+	reg.MustRegister(collectors.NewGoCollector())
+	m := NewMetrics(reg)
+	m.devices.Set(float64(len(devices)))
+	m.info.With(prometheus.Labels{"version": version}).Set(1)
+
+	promHandler := promhttp.HandlerFor(reg, promhttp.HandlerOpts{
+		Registry: reg,
+	})
+	app.metricsRouter.Handle("/metrics", promHandler)
+	rdh := registerDevicesHandler{metrics: m}
+	mdh := manageDevicesHandler{metrics: m}
+	lh := loginHandler{}
+	mlh := middleware(lh, m)
+	app.deviceRouter.Handle("/devices", rdh)
+	app.deviceRouter.Handle("/devices/", mdh)
+	app.deviceRouter.Handle("/login", mlh)
+}
+
+func getDevices(w http.ResponseWriter, _ *http.Request, m *metrics) {
+	now := time.Now()
+	b, err := json.Marshal(devices)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+	sleep(200)
+
+	m.duration.With(prometheus.Labels{"method": "GET", "status": "200"}).Observe(time.Since(now).Seconds())
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusOK)
+	w.Write(b)
+}
+
+func NewMetrics(reg prometheus.Registerer) *metrics {
+	m := &metrics{
+		devices: prometheus.NewGauge(prometheus.GaugeOpts{
+			Namespace: "myapp",
+			Name:      "connected_devices",
+			Help:      "Number of currently connected devices",
+		}),
+		info: prometheus.NewGaugeVec(prometheus.GaugeOpts{
+			Namespace: "myapp",
+			Name:      "info",
+			Help:      "Information about the My App enviroment",
+		}, []string{"version"}),
+		upgrades: prometheus.NewCounterVec(prometheus.CounterOpts{
+			Namespace: "myapp",
+			Name:      "device_upgrade_total",
+			Help:      "Number of upgraded devices",
+		}, []string{"type"}),
+		duration: prometheus.NewHistogramVec(prometheus.HistogramOpts{
+			Namespace: "myapp",
+			Name:      "request_duration_seconds",
+			Help:      "Duration of the request.",
+			// 4 times larger of apdex score
+			// Buckets: prometheus.ExponentialBuckets(0.1, 1.5, 5),
+			// Buckets: prometheus.LinearBuckets(0.1, 5, 5),
+			Buckets: []float64{0.1, 0.15, 0.2, 0.25, 0.3},
+		}, []string{"status", "method"}),
+		loginDuration: prometheus.NewSummary(prometheus.SummaryOpts{
+			Namespace:  "myapp",
+			Name:       "login_request_duration_seconds",
+			Help:       "Duration of the login request",
+			Objectives: map[float64]float64{0.5: 0.05, 0.9: 0.01, 0.99: 0.001},
+		}),
+	}
+	reg.MustRegister(m.devices, m.info, m.upgrades, m.duration, m.loginDuration)
+	return m
+}
+
+func (rdh registerDevicesHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	switch r.Method {
+	case "GET":
+		getDevices(w, r, rdh.metrics)
+	case "POST":
+		createDevice(w, r, rdh.metrics)
+	default:
+		w.Header().Set("Allow", "GET, POST")
+		http.Error(w, "Method Not Allowed", http.StatusMethodNotAllowed)
+	}
+
+}
+
+func createDevice(w http.ResponseWriter, r *http.Request, m *metrics) {
+	var device Device
+
+	err := json.NewDecoder(r.Body).Decode(&device)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+
+	devices = append(devices, device)
+	m.devices.Set(float64(len(devices)))
+
+	w.WriteHeader(http.StatusCreated)
+	w.Write([]byte("Device created!"))
+}
+
+func upgradeDevice(w http.ResponseWriter, r *http.Request, m *metrics) {
+	path := strings.TrimPrefix(r.URL.Path, "/devices/")
+
+	id, err := strconv.Atoi(path)
+	if err != nil || id < 1 {
+		http.NotFound(w, r)
+		return
+	}
+
+	var device Device
+	err = json.NewDecoder(r.Body).Decode(&device)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+
+	for i := range devices {
+		if devices[i].ID == id {
+			devices[i].Firmware = device.Firmware
+		}
+	}
+
+	sleep(1000)
+
+	m.upgrades.With(prometheus.Labels{"type": "router"}).Inc()
+	w.WriteHeader(http.StatusAccepted)
+	w.Write([]byte("Upgrading..."))
+}
+
+type manageDevicesHandler struct {
+	metrics *metrics
+}
+
+func (mdh manageDevicesHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	switch r.Method {
+	case "PUT":
+		upgradeDevice(w, r, mdh.metrics)
+	default:
+		w.Header().Set("Allow", "PUT")
+		http.Error(w, "Method Not Allowed", http.StatusMethodNotAllowed)
+	}
+}
+
+func sleep(ms int) {
+	randGenerator := rand.New(rand.NewSource(time.Now().UnixNano()))
+	now := time.Now()
+	n := randGenerator.Intn(ms + now.Second())
+	time.Sleep(time.Duration(n) * time.Millisecond)
+}
+
+type loginHandler struct{}
+
+func (l loginHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	sleep(200)
+	w.Write([]byte("Welcome to the app!"))
+}
+
+func middleware(next http.Handler, m *metrics) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		now := time.Now()
+		next.ServeHTTP(w, r)
+		m.loginDuration.Observe(time.Since(now).Seconds())
+	})
+}
+
+```
+## metric this sample could build
+
+![alt text](metric-sample.png)

Taskfile.yml

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+version: '3'
+
+dotenv: ['.env']
+
+tasks:
+  default:
+    cmds:
+      - echo "PORT=$PORT"
+    silent: true
+  
+  # build:
+  #   cmds:
+  #     - CGO_ENABLED=0 GOOS=linux go build -o bin/main cmd/main.go
+  #   silent: true
+  # run:
+  #   cmds:
+  #     - ./bin/main
+  #   deps:
+  #     - build
+  #   silent: true
+
+  build-mage:
+    cmds:
+      - CGO_ENABLED=0 GOOS=linux go build -o ./mage mage-tools/mage.go
+    silent: true
+  
+  build-gg:
+    cmds:
+      - ./mage -d mage-tools -compile ../gg
+    deps:
+      - build-mage
+    silent: true
+
+  coverage:
+    cmds:
+      - go test -v -cover ./...
+    silent: true
+  test:
+    cmds:
+      - go test -v ./...
+    silent: true
+  

cmd/main.go

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+package main
+
+import (
+	"context"
+	"log"
+	"os"
+	"os/signal"
+	"syscall"
+
+	"github.com/leetcode-golang-classroom/golang-sample-with-prometheus/internal/application"
+	"github.com/leetcode-golang-classroom/golang-sample-with-prometheus/internal/config"
+)
+
+func main() {
+	// 建立 application instance
+	app := application.New(config.AppConfig)
+	// 設定中斷訊號監聽
+	ctx, cancel := signal.NotifyContext(context.Background(), os.Interrupt,
+		syscall.SIGTERM, syscall.SIGINT)
+	defer cancel()
+	err := app.Start(ctx)
+	if err != nil {
+		log.Println("failed to start app:", err)
+	}
+}

docker-compose.yml

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+services:
+  myapp:
+    container_name: myapp
+    build:
+      context: .
+    ports:
+      - 8080:8080
+      - 8081:8081
+    environment:
+      - VERSION=2.10.5
+      - PORT=8080
+      - DEVICE_PORT=8081
+  
+  prometheus:
+    image: prom/prometheus:v2.40.4
+    ports:
+      - 9090:9090
+    volumes:
+      - ./prometheus/prometheus.yml:/etc/prometheus/prometheus.yml
+
+  grafana:
+    image: grafana/grafana:9.3.0
+    ports:
+      - 3000:3000
+    environment:
+      - GF_SECURITY_ADMIN_USER=admin
+      - GF_SECURITY_ADMIN_PASSWORD=devops123
+    volumes:
+      - ./grafana/datasources.yaml:/etc/grafana/provisioning/datasources/datasources.yaml
+      - grafana:/var/lib/grafana
+
+volumes:
+  grafana: