refactor: complete rewrite

.cspell.json

@@ -1,20 +1,26 @@
 {
   "ignorePaths": [
+    ".golangci.yaml", // Configuration file with a lot of Go specific words
     "go.mod", // This file is managed by Go
     "go.sum", // This file is managed by Go
     "LICENSE" // This file was automatically generated by Gitea
   ],
   "words": [
+    "aireone",
     "buildx",
     "distroless",
     "Gitea",
     "gocron",
     "golangci",
     "hadolint",
+    "healthcheckers",
     "labtime",
     "nonroot",
     "promhttp",
+    "prommonitors",
+    "proxied",
     "sigchan",
-    "woodpeckerci"
+    "woodpeckerci",
+    "yamlconfig"
   ]
 }

.golangci.yaml

@@ -1,7 +1,50 @@
 ---
-run:
-  timeout: 5m
-  # this settings is for the CI pipeline because it fails with the default value
-  # we should have used the --timeout flag in the CI pipeline
-  # but to make the linter work locally, I need to have a config file
-  # so I pushed this config file until we have something to do here 
+linters:
+  enable:
+    - asasalint
+    - bodyclose
+    - contextcheck
+    - copyloopvar
+    - depguard
+    - durationcheck
+    - errcheck 
+    - errname
+    - errorlint
+    - gocritic
+    - godot
+    - gofumpt
+    - goimports
+    - gosec
+    - gosimple
+    - govet
+    - ineffassign
+    - misspell
+    - nilerr
+    - nilnil
+    - noctx
+    - nolintlint
+    - prealloc
+    - predeclared
+    - promlinter
+    - reassign
+    - revive
+    - staticcheck
+    - tenv
+    - testableexamples
+    - thelper
+    - tparallel
+    - typecheck
+    - unconvert
+    - unused
+    - unparam
+    - usestdlibvars
+    - wastedassign
+linters-settings:
+  depguard:
+    rules:
+      main:
+        list-mode: lax
+        allow: [aireone.xyz/labtime] # It's mendatory to have at least one package in allow or deny list
+  errcheck:
+    check-type-assertions: true 
+    check-blank: true

.vscode/launch.json

@@ -0,0 +1,16 @@
+{
+  // Use IntelliSense to learn about possible attributes.
+  // Hover to view descriptions of existing attributes.
+  // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+  "version": "0.2.0",
+  "configurations": [
+    {
+      "name": "Launch Package",
+      "type": "go",
+      "request": "launch",
+      "mode": "auto",
+      "program": "${workspaceFolder}/cmd/labtime/main.go",
+      "args": ["-config", "../../configs/example-config.yaml"]
+    }
+  ]
+}

.vscode/settings.json

@@ -1,11 +1,8 @@
 {
-  "[go]": {
-    "editor.codeActionsOnSave": {
-      // "source.organizeImports": "always"
-    },
-    "editor.formatOnSave": true
-  },
-  "go.formatTool": "goimports",
-  "go.lintTool": "golangci-lint"
-  // "go.lintFlags": ["--fast"] // We only have the default linters and it seems they are not marked as fast, but it's fast enough for me
+  "go.lintTool": "golangci-lint",
+  "go.lintFlags": ["--fast"],
+  "go.useLanguageServer": true,
+  "gopls": {
+    "formatting.gofumpt": true
+  }
 }

cmd/labtime/main.go

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"log"
+	"os"
+
+	"aireone.xyz/labtime/internal/apps/labtime"
+)
+
+const (
+	loggerPrefix = "main:"
+)
+
+func main() {
+	logger := log.New(os.Stdout, loggerPrefix, log.LstdFlags|log.Lshortfile)
+	cfg := labtime.LoadFlag()
+
+	app, err := labtime.NewApp(cfg, logger)
+	if err != nil {
+		logger.Fatalf("Error creating app: %v", err)
+	}
+
+	if err := app.Start(); err != nil {
+		logger.Fatalf("Error starting app: %v", err)
+	}
+}

go.mod

@@ -15,6 +15,7 @@ require (
 	github.com/jonboulle/clockwork v0.4.0 // indirect
 	github.com/klauspost/compress v1.17.9 // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
 	github.com/prometheus/client_model v0.6.1 // indirect
 	github.com/prometheus/common v0.55.0 // indirect
 	github.com/prometheus/procfs v0.15.1 // indirect

go.sum

@@ -18,6 +18,8 @@ github.com/klauspost/compress v1.17.9 h1:6KIumPrER1LHsvBVuDa0r5xaG0Es51mhhB9BQB2
 github.com/klauspost/compress v1.17.9/go.mod h1:Di0epgTjJY877eYKx5yC51cX2A2Vl2ibi7bDH9ttBbw=
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 h1:C3w9PqII01/Oq1c1nUAm88MOHcQC9l5mIlSMApZMrHA=
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822/go.mod h1:+n7T8mK8HuQTcFwEeznm/DIxMOiR9yIdICNftLE1DvQ=
+github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
+github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/prometheus/client_golang v1.19.1 h1:wZWJDwK+NameRJuPGDhlnFgx8e8HN3XHQeLaYJFJBOE=
 github.com/prometheus/client_golang v1.19.1/go.mod h1:mP78NwGzrVks5S2H6ab8+ZZGJLZUq1hoULYBAYBw1Ho=
 github.com/prometheus/client_golang v1.20.2 h1:5ctymQzZlyOON1666svgwn3s6IKWgfbjsejTMiXIyjg=

internal/apps/labtime/app.go

@@ -0,0 +1,107 @@
+package labtime
+
+import (
+	"context"
+	"log"
+	"net/http"
+	"os"
+	"time"
+
+	"aireone.xyz/labtime/internal/monitors"
+	"aireone.xyz/labtime/internal/scheduler"
+	"aireone.xyz/labtime/internal/yamlconfig"
+	"github.com/pkg/errors"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+type App struct {
+	scheduler            *scheduler.Scheduler
+	prometheusHTTPServer *http.Server
+
+	logger *log.Logger
+}
+
+func NewApp(flag *FlagConfig, logger *log.Logger) (*App, error) {
+	config, err := loadYamlConfig(flag.configFile)
+	if err != nil {
+		return nil, errors.Wrap(err, "error loading yaml config")
+	}
+
+	scheduler, err := createScheduler(config, logger)
+	if err != nil {
+		return nil, errors.Wrap(err, "error creating scheduler")
+	}
+
+	return &App{
+		logger:    logger,
+		scheduler: scheduler,
+		prometheusHTTPServer: &http.Server{
+			Addr:         ":2112",
+			ReadTimeout:  5 * time.Second,
+			WriteTimeout: 10 * time.Second,
+			IdleTimeout:  15 * time.Second,
+		},
+	}, nil
+}
+
+func loadYamlConfig(configFile string) (*yamlconfig.YamlConfig, error) {
+	file, err := os.Open(configFile)
+	if err != nil {
+		return nil, errors.Wrap(err, "error opening config file")
+	}
+
+	defer file.Close()
+
+	return yamlconfig.NewYamlConfig(file)
+}
+
+func createScheduler(config *yamlconfig.YamlConfig, logger *log.Logger) (*scheduler.Scheduler, error) {
+	scheduler, err := scheduler.NewScheduler(logger)
+	if err != nil {
+		return nil, errors.Wrap(err, "error creating scheduler")
+	}
+
+	httpMonitor := prometheus.NewGaugeVec(prometheus.GaugeOpts{
+		Name: "labtime_response_time_duration",
+		Help: "The ping time.",
+	}, []string{"target_name"})
+	prometheus.MustRegister(httpMonitor)
+
+	for _, t := range config.Targets {
+		if err := scheduler.AddJob(&monitors.HTTPMonitor{
+			Label:               t.Name,
+			URL:                 t.URL,
+			Logger:              logger,
+			ResponseTimeMonitor: httpMonitor,
+		}, t.Interval); err != nil {
+			return nil, errors.Wrap(err, "error adding job")
+		}
+	}
+
+	return scheduler, nil
+}
+
+func (a *App) Start() error {
+	a.scheduler.Start()
+
+	// Serve Prometheus metrics
+	http.Handle("/metrics", promhttp.Handler())
+	if err := a.prometheusHTTPServer.ListenAndServe(); err != nil && err != http.ErrServerClosed {
+		return errors.Wrap(err, "error starting prometheus http server")
+	}
+
+	return nil
+}
+
+func (a *App) Shutdown() error {
+	if err := a.scheduler.Shutdown(); err != nil {
+		return errors.Wrap(err, "error shutting down scheduler")
+	}
+
+	if err := a.prometheusHTTPServer.Shutdown(context.TODO()); err != nil {
+		return errors.Wrap(err, "error shutting down prometheus http server")
+	}
+
+	return nil
+}

internal/apps/labtime/flag.go

@@ -0,0 +1,18 @@
+package labtime
+
+import "flag"
+
+const (
+	defaultConfigFile = "config.yaml"
+)
+
+type FlagConfig struct {
+	configFile string
+}
+
+func LoadFlag() *FlagConfig {
+	cfg := FlagConfig{}
+	flag.StringVar(&cfg.configFile, "config", defaultConfigFile, "Path to the configuration file")
+	flag.Parse()
+	return &cfg
+}

internal/http/middlewares.go

@@ -0,0 +1,33 @@
+package http
+
+import (
+	"log"
+	"net/http"
+)
+
+type RoundTripperMiddleware struct {
+	Proxied http.RoundTripper
+
+	OnBefore func(req *http.Request)
+	OnAfter  func(res *http.Response)
+}
+
+func (m RoundTripperMiddleware) RoundTrip(req *http.Request) (res *http.Response, err error) {
+	m.OnBefore(req)
+	res, err = m.Proxied.RoundTrip(req)
+	m.OnAfter(res)
+
+	return res, err
+}
+
+func NewLoggerMiddleware(logger *log.Logger, proxied http.RoundTripper) *RoundTripperMiddleware {
+	return &RoundTripperMiddleware{
+		Proxied: proxied,
+		OnBefore: func(req *http.Request) {
+			logger.Printf("Request: %s %s", req.Method, req.URL.String())
+		},
+		OnAfter: func(res *http.Response) {
+			logger.Printf("Response: %d", res.StatusCode)
+		},
+	}
+}

internal/monitors/httpmonitor.go

@@ -0,0 +1,88 @@
+package monitors
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"net/http"
+	"time"
+
+	aireoneHttp "aireone.xyz/labtime/internal/http"
+	"github.com/pkg/errors"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+var ErrInvalidStatusCode = errors.New("expected status code 200")
+
+type HTTPMonitor struct {
+	Label string
+	URL   string
+
+	Logger *log.Logger
+
+	ResponseTimeMonitor *prometheus.GaugeVec
+}
+
+func (h *HTTPMonitor) ID() string {
+	return h.Label
+}
+
+func (h *HTTPMonitor) Run() error {
+	d, err := h.httpHealthCheck()
+	if err != nil {
+		return errors.Wrap(err, "error running http health check")
+	}
+
+	h.pushToPrometheus(d)
+
+	return nil
+}
+
+func newHTTPDurationMiddleware(duration *time.Duration, proxied http.RoundTripper) *aireoneHttp.RoundTripperMiddleware {
+	var t time.Time
+
+	return &aireoneHttp.RoundTripperMiddleware{
+		Proxied: proxied,
+		OnBefore: func(_ *http.Request) {
+			t = time.Now()
+		},
+		OnAfter: func(_ *http.Response) {
+			*duration = time.Since(t)
+		},
+	}
+}
+
+type HTTPHealthCheckerData struct {
+	Duration time.Duration
+}
+
+func (h *HTTPMonitor) httpHealthCheck() (*HTTPHealthCheckerData, error) {
+	r, err := http.NewRequest(http.MethodHead, h.URL, http.NoBody)
+	if err != nil {
+		return nil, errors.Wrap(err, "error creating http request")
+	}
+	req := r.WithContext(context.TODO())
+
+	var duration time.Duration
+	client := &http.Client{
+		Transport: aireoneHttp.NewLoggerMiddleware(h.Logger, newHTTPDurationMiddleware(&duration, http.DefaultTransport)),
+	}
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, errors.Wrap(ErrInvalidStatusCode, fmt.Sprintf("got status code %d", resp.StatusCode))
+	}
+
+	return &HTTPHealthCheckerData{
+		Duration: duration,
+	}, nil
+}
+
+func (h *HTTPMonitor) pushToPrometheus(d *HTTPHealthCheckerData) {
+	h.Logger.Printf("Push metrics to Prometheus: Response time for %s: %v", h.Label, d.Duration.Seconds())
+	h.ResponseTimeMonitor.With(prometheus.Labels{"target_name": h.Label}).Set(d.Duration.Seconds())
+}

internal/monitors/monitor.go

@@ -0,0 +1,6 @@
+package monitors
+
+type Monitor interface {
+	ID() string
+	Run() error
+}

internal/scheduler/scheduler.go

@@ -0,0 +1,60 @@
+package scheduler
+
+import (
+	"log"
+	"time"
+
+	"aireone.xyz/labtime/internal/monitors"
+	"github.com/go-co-op/gocron/v2"
+	"github.com/pkg/errors"
+)
+
+type Scheduler struct {
+	scheduler gocron.Scheduler
+
+	logger *log.Logger
+}
+
+func NewScheduler(logger *log.Logger) (*Scheduler, error) {
+	s, err := gocron.NewScheduler()
+	if err != nil {
+		return nil, errors.Wrap(err, "error creating scheduler")
+	}
+
+	return &Scheduler{
+		scheduler: s,
+		logger:    logger,
+	}, nil
+}
+
+func (s *Scheduler) AddJob(m monitors.Monitor, interval int) error {
+	j, err := s.scheduler.NewJob(
+		gocron.DurationJob(time.Duration(interval)*time.Second),
+		gocron.NewTask(func() {
+			s.logger.Printf("Running job for HTTP monitor %s\n", m.ID())
+			if err := m.Run(); err != nil {
+				s.logger.Printf("Error running job for HTTP monitor %s: %s\n", m.ID(), err)
+			}
+			s.logger.Printf("Job finished for HTTP monitor %s\n", m.ID())
+		}),
+	)
+	if err != nil {
+		return errors.Wrap(err, "error creating job")
+	}
+
+	s.logger.Printf("Job started for HTTP monitor %s with ID: %s\n", m.ID(), j.ID().String())
+
+	return nil
+}
+
+func (s *Scheduler) Start() {
+	s.scheduler.Start()
+}
+
+func (s *Scheduler) Shutdown() error {
+	if err := s.scheduler.Shutdown(); err != nil {
+		return errors.Wrap(err, "error shutting down scheduler")
+	}
+
+	return nil
+}

internal/yamlconfig/yamlconfig.go

@@ -0,0 +1,45 @@
+package yamlconfig
+
+import (
+	"io"
+
+	"github.com/pkg/errors"
+	"gopkg.in/yaml.v3"
+)
+
+var ErrYAMLDecode = errors.New("error decoding YAML file")
+
+type YamlConfig struct {
+	// List of targets to ping.
+	Targets []struct {
+		// Name of the target. Used to identify the target from Prometheus.
+		Name string `yaml:"name"`
+		// URL of the target. The target should be accessible from the machine running the exporter.
+		// The URL should contain the protocol (http:// or https://) and the port if it's not the default one.
+		URL string `yaml:"url"`
+		// Interval to ping the target. Default is 5 seconds.
+		Interval int `yaml:"interval,omitempty"`
+	} `yaml:"targets"`
+}
+
+func NewYamlConfig(r io.Reader) (*YamlConfig, error) {
+	d := yaml.NewDecoder(r)
+	config := &YamlConfig{}
+
+	if err := d.Decode(&config); err != nil {
+		return nil, errors.Wrap(ErrYAMLDecode, err.Error())
+	}
+
+	applyDefault(config)
+
+	return config, nil
+}
+
+func applyDefault(config *YamlConfig) {
+	// Set default interval to 5 seconds if not provided
+	for i := range config.Targets {
+		if config.Targets[i].Interval == 0 {
+			config.Targets[i].Interval = 5
+		}
+	}
+}

main.go

@@ -1,182 +0,0 @@
-package main
-
-import (
-	"crypto/tls"
-	"fmt"
-	"log"
-	"net/http"
-	"net/http/httptrace"
-	"os"
-	"os/signal"
-	"time"
-
-	"github.com/go-co-op/gocron/v2"
-	"github.com/prometheus/client_golang/prometheus"
-	"github.com/prometheus/client_golang/prometheus/promhttp"
-	"gopkg.in/yaml.v3"
-)
-
-type Config struct {
-	// List of targets to ping
-	Targets []struct {
-		// Name of the target. Used to identify the target from Prometheus.
-		Name string `yaml:"name"`
-		// URL of the target. The target should be accessible from the machine running the exporter.
-		// The URL should contain the protocol (http:// or https://) and the port if it's not the default one.
-		Url string `yaml:"url"`
-		// Interval to ping the target. Default is 5 seconds
-		Interval int `yaml:"interval,omitempty"`
-	} `yaml:"targets"`
-}
-
-func NewConfig(configPath string) (*Config, error) {
-	// Create config structure
-	config := &Config{}
-
-	// Open config file
-	file, err := os.Open(configPath)
-	if err != nil {
-		return nil, err
-	}
-	defer file.Close()
-
-	// Init new YAML decode
-	d := yaml.NewDecoder(file)
-
-	// Start YAML decoding from file
-	if err := d.Decode(&config); err != nil {
-		return nil, err
-	}
-
-	return config, nil
-}
-
-func Ping(url string) (int, time.Duration, error) {
-	req, err := http.NewRequest(http.MethodHead, url, nil)
-	if err != nil {
-		return 0, 0, err
-	}
-
-	var start, connect, dns, tlsHandshake time.Time
-
-	trace := &httptrace.ClientTrace{
-		DNSStart: func(dsi httptrace.DNSStartInfo) { dns = time.Now() },
-		DNSDone: func(ddi httptrace.DNSDoneInfo) {
-			fmt.Printf("DNS Done: %v\n", time.Since(dns))
-		},
-
-		TLSHandshakeStart: func() { tlsHandshake = time.Now() },
-		TLSHandshakeDone: func(cs tls.ConnectionState, err error) {
-			fmt.Printf("TLS Handshake: %v\n", time.Since(tlsHandshake))
-		},
-
-		ConnectStart: func(network, addr string) { connect = time.Now() },
-		ConnectDone: func(network, addr string, err error) {
-			fmt.Printf("Connect time: %v\n", time.Since(connect))
-		},
-
-		GotFirstResponseByte: func() {
-			fmt.Printf("Time from start to first byte: %v\n", time.Since(start))
-		},
-	}
-
-	req = req.WithContext(httptrace.WithClientTrace(req.Context(), trace))
-	start = time.Now()
-
-	resp, err := http.DefaultTransport.RoundTrip(req)
-	if err != nil {
-		return 0, 0, err
-	}
-
-    defer resp.Body.Close()
-
-	return resp.StatusCode, time.Since(start), nil
-}
-
-func main() {
-	// Load config
-	// TODO: Use a flag to specify the config file
-	config, err := NewConfig("config/config.yaml")
-	if err != nil {
-		log.Fatalf("Error loading config: %s", err)
-	}
-	// Print config
-	fmt.Printf("%+v\n", config)
-
-	// create a scheduler
-	s, err := gocron.NewScheduler()
-	if err != nil {
-        log.Fatalf("Error creating the scheduler: %s",err)
-	}
-
-	// Prometheus metrics
-	responseTimeMonitor := prometheus.NewGaugeVec(prometheus.GaugeOpts{
-		Name: "labtime_response_time_duration",
-		Help: "The ping time.",
-	}, []string{"target_name"})
-	prometheus.MustRegister(responseTimeMonitor)
-
-	// Intercept the signal to stop the program
-	go func() {
-		sigchan := make(chan os.Signal, 1)
-		signal.Notify(sigchan, os.Interrupt)
-		<-sigchan
-		log.Println("Program killed !")
-
-		// do last actions and wait for all write operations to end
-
-		// when you're done, shut it down
-		err = s.Shutdown()
-		if err != nil {
-            log.Fatalf("Error shutting down scheduler: %s", err)
-		}
-
-		os.Exit(0)
-	}()
-
-	// add a job to the scheduler
-	for _, target := range config.Targets {
-		j, err := s.NewJob(
-			gocron.DurationJob(
-				func(interval int) time.Duration {
-					if interval == 0 {
-						const defaultInterval = 5
-
-						return time.Duration(defaultInterval) * time.Second
-					}
-
-					return time.Duration(interval) * time.Second
-				}(target.Interval),
-			),
-			gocron.NewTask(
-				func(url string) {
-					status, elapsedTime, err := Ping(url)
-					if err != nil {
-						fmt.Println(err)
-
-						return
-					}
-
-					fmt.Printf("%s - Status: %d in %v\n", target.Name, status, elapsedTime.Seconds())
-					// push to Prometheus
-					responseTimeMonitor.With(prometheus.Labels{"target_name": target.Name}).Set(elapsedTime.Seconds())
-				},
-				target.Url,
-			),
-		)
-		if err != nil {
-            log.Fatalf("Error creating job: %s", err)
-		}
-		// each job has a unique id
-		fmt.Printf("Job %s started with ID: %s\n", target.Name, j.ID().String())
-	}
-
-	// start the scheduler
-	s.Start()
-
-	// Serve Prometheus metrics
-	http.Handle("/metrics", promhttp.Handler())
-	if err := http.ListenAndServe(":2112", nil); err != nil {
-		log.Fatalf("Error starting server: %s", err)
-	}
-}