change(service-account-server): use a random free port

Author: l3uddz

cmd/sync.go

@@ -126,6 +126,7 @@ func performSync(s *syncer.Syncer) error {
 	if strings.Contains(s.GlobalConfig.Rclone.Path, "gclone") {
 		// start web-server
 		s.Ws.Run()
+		defer s.Ws.Stop()
 
 		gcloneParams = append(gcloneParams,
 			"--drive-service-account-url",

go.mod

@@ -19,6 +19,7 @@ require (
 	github.com/onsi/ginkgo v1.12.0 // indirect
 	github.com/onsi/gomega v1.9.0 // indirect
 	github.com/pelletier/go-toml v1.7.0 // indirect
+	github.com/phayes/freeport v0.0.0-20180830031419-95f893ade6f2
 	github.com/pkg/errors v0.9.1
 	github.com/rhysd/go-github-selfupdate v1.2.2
 	github.com/sirupsen/logrus v1.6.0

go.sum

@@ -225,6 +225,8 @@ github.com/pelletier/go-toml v1.2.0 h1:T5zMGML61Wp+FlcbWjRDT7yAxhJNAiPPLOFECq181
 github.com/pelletier/go-toml v1.2.0/go.mod h1:5z9KED0ma1S8pY6P1sdut58dfprrGBbd/94hg7ilaic=
 github.com/pelletier/go-toml v1.7.0 h1:7utD74fnzVc/cpcyy8sjrlFr5vYpypUixARcHIMIGuI=
 github.com/pelletier/go-toml v1.7.0/go.mod h1:vwGMzjaWMwyfHwgIBhI2YUM4fB6nL6lVAvS1LBMMhTE=
+github.com/phayes/freeport v0.0.0-20180830031419-95f893ade6f2 h1:JhzVVoYvbOACxoUmOs6V/G4D5nPVUW73rKvXxP4XUJc=
+github.com/phayes/freeport v0.0.0-20180830031419-95f893ade6f2/go.mod h1:iIss55rKnNBTvrwdmkUpLnDpZoAHvWaiq5+iMmen4AE=
 github.com/philhofer/fwd v1.0.0 h1:UbZqGr5Y38ApvM/V/jEljVxwocdweyH+vmYvRPBnbqQ=
 github.com/philhofer/fwd v1.0.0/go.mod h1:gk3iGcWd9+svBvR0sR+KPcfE+RNWozjowpeBVG3ZVNU=
 github.com/pkg/errors v0.8.0/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=

syncer/syncer.go

@@ -40,7 +40,7 @@ func New(config *config.Configuration, syncerConfig *config.SyncerConfig, syncer
 		Config:                    syncerConfig,
 		Name:                      syncerName,
 		RemoteServiceAccountFiles: sam,
-		Ws:                        newWebServer("127.0.0.1", 3263, l, sam),
+		Ws:                        newWebServer("127.0.0.1", l, syncerName, sam),
 	}
 
 	return syncer, nil

syncer/web.go

@@ -6,30 +6,69 @@ import (
 	"github.com/gofiber/recover"
 	"github.com/l3uddz/crop/cache"
 	"github.com/l3uddz/crop/rclone"
+	"github.com/phayes/freeport"
 	"github.com/sirupsen/logrus"
+	"sync"
 )
 
 type WebServer struct {
-	Host string
-	Port int
+	Host       string
+	Port       int
+	app        *fiber.App
+	log        *logrus.Entry
+	syncerName string
+	sa         *rclone.ServiceAccountManager
+}
 
-	app *fiber.App
-	log *logrus.Entry
-	sa  *rclone.ServiceAccountManager
+type FreePortCache struct {
+	pCache map[int]int
+	sync.Mutex
 }
 
 type ServiceAccountRequest struct {
 	OldServiceAccount string `json:"old"`
 	Remote            string `json:"remote"`
 }
 
-func newWebServer(host string, port int, log *logrus.Entry, sa *rclone.ServiceAccountManager) *WebServer {
+var (
+	fpc *FreePortCache
+)
+
+func init() {
+	fpc = &FreePortCache{
+		pCache: make(map[int]int),
+		Mutex:  sync.Mutex{},
+	}
+}
+
+func newWebServer(host string, log *logrus.Entry, syncerName string, sa *rclone.ServiceAccountManager) *WebServer {
+	// get free port
+	fpc.Lock()
+	defer fpc.Unlock()
+	port := 0
+
+	for {
+		p, err := freeport.GetFreePort()
+		if err != nil {
+			log.WithError(err).Fatal("Failed locating free port for the service account server")
+		}
+
+		if _, exists := fpc.pCache[p]; !exists {
+			fpc.pCache[p] = p
+			port = p
+			log.Debugf("Found free port for service account server: %d", port)
+			break
+		}
+	}
+
+	// create ws object
 	ws := &WebServer{
-		Host: host,
-		Port: port,
-		app:  fiber.New(),
-		log:  log,
-		sa:   sa,
+		Host:       host,
+		Port:       port,
+		app:        fiber.New(),
+		log:        log,
+		syncerName: syncerName,
+		sa:         sa,
 	}
 
 	// setup app