Merge pull request #20 from trustpilot/windows-service

Windows service

Author: Audrius Karabanovas

.github/main.workflow

@@ -5,4 +5,5 @@ workflow "build-and-deploy" {
 
 action "build" {
   uses="cedrickring/golang-action/[email protected]"
+  args="make crossbuild"
 }

.gitignore

@@ -1,4 +1,6 @@
 vendor
 .build
 .tarballs
-beat-exporter
+.DS_Store
+beat-exporter
+beat-exporter.exe

Gopkg.lock

@@ -9,3 +9,7 @@
 [[constraint]]
   name = "github.com/sirupsen/logrus"
   version = "1.4.2"
+
+[[constraint]]
+  branch = "master"
+  name = "golang.org/x/sys"

Gopkg.toml

@@ -49,9 +49,10 @@ build: promu
 	@echo ">> building binaries"
 	@$(PROMU) build --prefix $(PREFIX)
 
-crossbuild: promu
+crossbuild: dependencies format vet test 
 	@echo ">> cross-building binaries"
-	@$(PROMU) crossbuild
+	@$(GO) get github.com/mitchellh/gox
+	@gox -arch="386 amd64" -os="linux darwin windows" --output=".build/{{.OS}}-{{.Arch}}/{{.Dir}}"
 
 tarball: promu
 	@echo ">> building release tarball"

Makefile

@@ -0,0 +1,24 @@
+// +build linux darwin
+
+package service
+
+import (
+	"os"
+	"os/signal"
+	"syscall"
+
+	log "github.com/sirupsen/logrus"
+)
+
+// SetupServiceListener setups singal handler
+func SetupServiceListener(stopCh chan<- bool, serviceName string, logger log.StdLogger) error {
+	go func() {
+		sigs := make(chan os.Signal, 1)
+		signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM, syscall.SIGKILL, syscall.SIGHUP)
+		logger.Printf("Signal received: %v", <-sigs)
+		stopCh <- true
+		close(stopCh)
+	}()
+
+	return nil
+}

internal/service/handler.go

@@ -0,0 +1,55 @@
+// +build windows
+
+package service
+
+import (
+	"fmt"
+	log "github.com/sirupsen/logrus"
+	"golang.org/x/sys/windows/svc"
+)
+
+type beatExporterService struct {
+	stopCh chan<- bool
+}
+
+func (s *beatExporterService) Execute(args []string, r <-chan svc.ChangeRequest, changes chan<- svc.Status) (ssec bool, errno uint32) {
+	const cmdsAccepted = svc.AcceptStop | svc.AcceptShutdown
+	changes <- svc.Status{State: svc.StartPending}
+	changes <- svc.Status{State: svc.Running, Accepts: cmdsAccepted}
+loop:
+	for {
+		select {
+		case c := <-r:
+			switch c.Cmd {
+			case svc.Interrogate:
+				changes <- c.CurrentStatus
+			case svc.Stop, svc.Shutdown:
+				s.stopCh <- true
+				break loop
+			default:
+				log.Error(fmt.Sprintf("unexpected control request #%d", c))
+			}
+		}
+	}
+	changes <- svc.Status{State: svc.StopPending}
+	return
+}
+
+// SetupServiceListener setups service handler for windows
+func SetupServiceListener(stopCh chan<- bool, serviceName string, logger log.StdLogger) error {
+	isInteractive, err := svc.IsAnInteractiveSession()
+	if err != nil {
+		return err
+	}
+
+	if !isInteractive {
+		go func() {
+			err = svc.Run(serviceName, &beatExporterService{stopCh: stopCh})
+			if err != nil {
+				logger.Printf("Failed to start service: %v", err)
+			}
+		}()
+	}
+
+	return nil
+}

internal/service/handler_windows.go

@@ -17,11 +17,16 @@ import (
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/prometheus/common/version"
 	"github.com/trustpilot/beat-exporter/collector"
+	"github.com/trustpilot/beat-exporter/internal/service"
+)
+
+const (
+	serviceName = "beat_exporter"
 )
 
 func main() {
 	var (
-		Name          = "beat_exporter"
+		Name          = serviceName
 		listenAddress = flag.String("web.listen-address", ":9479", "Address to listen on for web interface and telemetry.")
 		metricsPath   = flag.String("web.telemetry-path", "/metrics", "Path under which to expose metrics.")
 		beatURI       = flag.String("beat.uri", "http://localhost:5066", "HTTP API address of beat.")
@@ -57,16 +62,36 @@ func main() {
 
 	var beatInfo *collector.BeatInfo
 
+	stopCh := make(chan bool)
+
+	err = service.SetupServiceListener(stopCh, serviceName, log.StandardLogger())
+	if err != nil {
+		log.WithFields(log.Fields{
+			"err": err,
+		}).Errorf("could not setup service listener: %v", err)
+	}
+
+	t := time.NewTicker(1 * time.Second)
+
+beatdiscovery:
 	for {
-		beatInfo, err = loadBeatType(httpClient, *beatURL)
-		if err != nil {
-			log.Errorf("Could not load beat type, with error: %v, retrying in 5s", err)
-			time.Sleep(5 * time.Second)
-		} else {
-			break
+		select {
+		case <-t.C:
+			beatInfo, err = loadBeatType(httpClient, *beatURL)
+			if err != nil {
+				log.Errorf("Could not load beat type, with error: %v, retrying in 1s", err)
+				continue
+			}
+
+			break beatdiscovery
+
+		case <-stopCh:
+			os.Exit(0) // signal received, stop gracefully
 		}
 	}
 
+	t.Stop()
+
 	// version metric
 	registry := prometheus.NewRegistry()
 	versionMetric := version.NewCollector(Name)
@@ -88,17 +113,33 @@ func main() {
 		"addr": *listenAddress,
 	}).Infof("Starting exporter with configured type: %s", beatInfo.Beat)
 
-	if err := http.ListenAndServe(*listenAddress, nil); err != nil {
+	go func() {
+		defer func() {
+			stopCh <- true
+		}()
 
-		log.WithFields(log.Fields{
-			"err": err,
-		}).Errorf("http server quit with error: %v", err)
+		log.Info("Starting listener")
+		if err := http.ListenAndServe(*listenAddress, nil); err != nil {
+
+			log.WithFields(log.Fields{
+				"err": err,
+			}).Errorf("http server quit with error: %v", err)
+
+		}
+		log.Info("Listener exited")
+	}()
 
+	for {
+		if <-stopCh {
+			log.Info("Shutting down beats exporter")
+			break
+		}
 	}
 }
 
 // IndexHandler returns a http handler with the correct metricsPath
 func IndexHandler(metricsPath string) http.HandlerFunc {
+
 	indexHTML := `
 <html>
 	<head>