Ensure only one instance of tunnel process runs

cmd/minikube/cmd/tunnel.go

@@ -18,12 +18,14 @@ package cmd
 
 import (
 	"context"
+	"fmt"
 	"os"
 	"os/signal"
 	"path/filepath"
 	"runtime"
 	"strconv"
 
+	"github.com/juju/fslock"
 	"github.com/spf13/cobra"
 
 	"k8s.io/klog/v2"
@@ -44,6 +46,7 @@ import (
 
 var cleanup bool
 var bindAddress string
+var lockHandle *fslock.Lock
 
 // tunnelCmd represents the tunnel command
 var tunnelCmd = &cobra.Command{
@@ -73,6 +76,9 @@ var tunnelCmd = &cobra.Command{
 			}
 		}
 
+		mustLockOrExit()
+		defer cleanupLock()
+
 		// Tunnel uses the k8s clientset to query the API server for services in the LoadBalancerEmulator.
 		// We define the tunnel and minikube error free if the API server responds within a second.
 		// This also contributes to better UX, the tunnel status check can happen every second and
@@ -116,6 +122,28 @@ var tunnelCmd = &cobra.Command{
 	},
 }
 
+func cleanupLock() {
+	if lockHandle != nil {
+		err := lockHandle.Unlock()
+		if err != nil {
+			out.Styled(style.Warning, fmt.Sprintf("failed to release lock during cleanup: %v", err))
+		}
+	}
+}
+
+func mustLockOrExit() {
+	tunnelLockPath := filepath.Join(localpath.MiniPath(), ".tunnel_lock")
+
+	lockHandle = fslock.New(tunnelLockPath)
+	err := lockHandle.TryLock()
+	if err == fslock.ErrLocked {
+		exit.Message(reason.SvcTunnelAlreadyRunning, "Another tunnel process is already running, terminate the existing instance to start a new one")
+	}
+	if err != nil {
+		exit.Error(reason.SvcTunnelStart, "failed to acquire lock due to unexpected error", err)
+	}
+}
+
 func outputTunnelStarted() {
 	out.Styled(style.Success, "Tunnel successfully started")
 	out.Ln("")

pkg/minikube/reason/reason.go

@@ -420,6 +420,8 @@ var (
 	SvcTunnelStart = Kind{ID: "SVC_TUNNEL_START", ExitCode: ExSvcError}
 	// minikube could not stop an active tunnel
 	SvcTunnelStop = Kind{ID: "SVC_TUNNEL_STOP", ExitCode: ExSvcError}
+	// another instance of tunnel already running
+	SvcTunnelAlreadyRunning = Kind{ID: "TUNNEL_ALREADY_RUNNING", ExitCode: ExSvcConflict, Style: style.Usage}
 	// minikube was unable to access the service url
 	SvcURLTimeout = Kind{ID: "SVC_URL_TIMEOUT", ExitCode: ExSvcTimeout}
 	// minikube couldn't find the specified service in the specified namespace

site/content/en/docs/contrib/errorcodes.en.md

@@ -406,6 +406,9 @@ minikube failed to start a tunnel
 "SVC_TUNNEL_STOP" (Exit code ExSvcError)  
 minikube could not stop an active tunnel  
 
+"TUNNEL_ALREADY_RUNNING" (Exit code ExSvcConflict)  
+another instance of tunnel already running  
+
 "SVC_URL_TIMEOUT" (Exit code ExSvcTimeout)  
 minikube was unable to access the service url  
 

site/content/en/docs/contrib/tests.en.md

@@ -409,6 +409,9 @@ makes sure the minikube tunnel command works as expected
 #### validateTunnelStart
 starts `minikube tunnel`
 
+#### validateNoSecondTunnel
+ensures only 1 tunnel can run simultaneously
+
 #### validateServiceStable
 starts nginx pod, nginx service and waits nginx having loadbalancer ingress IP
 

test/integration/functional_test_tunnel_test.go

@@ -38,6 +38,7 @@ import (
 	"k8s.io/minikube/pkg/kapi"
 	"k8s.io/minikube/pkg/minikube/config"
 	"k8s.io/minikube/pkg/minikube/detect"
+	"k8s.io/minikube/pkg/minikube/reason"
 	"k8s.io/minikube/pkg/util"
 	"k8s.io/minikube/pkg/util/retry"
 )
@@ -61,6 +62,7 @@ func validateTunnelCmd(ctx context.Context, t *testing.T, profile string) {
 			name      string
 			validator validateFunc
 		}{
+			{"RunSecondTunnel", validateNoSecondTunnel},            // Ensure no two tunnels run simultaneously
 			{"StartTunnel", validateTunnelStart},                   // Start tunnel
 			{"WaitService", validateServiceStable},                 // Wait for service is stable
 			{"AccessDirect", validateAccessDirect},                 // Access test for loadbalancer IP
@@ -131,6 +133,69 @@ func validateTunnelStart(ctx context.Context, t *testing.T, profile string) {
 	tunnelSession = *ss
 }
 
+// validateNoSecondTunnel ensures only 1 tunnel can run simultaneously
+func validateNoSecondTunnel(ctx context.Context, t *testing.T, profile string) {
+	checkRoutePassword(t)
+
+	type SessInfo struct {
+		Stdout   string
+		Stderr   string
+		ExitCode int
+	}
+
+	sessCh := make(chan SessInfo)
+	sessions := make([]*StartSession, 2)
+
+	var runTunnel = func(idx int) {
+		args := []string{"-p", profile, "tunnel", "--alsologtostderr"}
+
+		ctx2, cancel := context.WithTimeout(ctx, Seconds(15))
+		defer cancel()
+		session, err := Start(t, exec.CommandContext(ctx2, Target(), args...))
+		if err != nil {
+			t.Errorf("failed to start tunnel: %v", err)
+		}
+		sessions[idx] = session
+
+		stderr, err := io.ReadAll(session.Stderr)
+		if err != nil {
+			t.Logf("Failed to read stderr: %v", err)
+		}
+		stdout, err := io.ReadAll(session.Stdout)
+		if err != nil {
+			t.Logf("Failed to read stdout: %v", err)
+		}
+
+		exitCode := 0
+		err = session.cmd.Wait()
+		if err != nil {
+			if exErr, ok := err.(*exec.ExitError); !ok {
+				t.Logf("failed to coerce exit error: %v", err)
+				exitCode = -1
+			} else {
+				exitCode = exErr.ExitCode()
+			}
+		}
+
+		sessCh <- SessInfo{Stdout: string(stdout), Stderr: string(stderr), ExitCode: exitCode}
+	}
+
+	// One of the two processes must fail to acquire lock and die. This should be the first process to die.
+	go runTunnel(0)
+	go runTunnel(1)
+
+	sessInfo := <-sessCh
+
+	if sessInfo.ExitCode != reason.SvcTunnelAlreadyRunning.ExitCode {
+		t.Errorf("tunnel command failed with unexpected error: exit code %d. stderr: %s\n stdout: %s", sessInfo.ExitCode, sessInfo.Stderr, sessInfo.Stdout)
+	}
+
+	for _, sess := range sessions {
+		sess.Stop(t)
+	}
+	<-sessCh
+}
+
 // validateServiceStable starts nginx pod, nginx service and waits nginx having loadbalancer ingress IP
 func validateServiceStable(ctx context.Context, t *testing.T, profile string) {
 	if detect.GithubActionRunner() && runtime.GOOS == "darwin" {

translations/de.json

@@ -71,6 +71,7 @@
 	"Another hypervisor, such as VirtualBox, is conflicting with KVM. Please stop the other hypervisor, or use --driver to switch to it.": "Ein anderer Hypervisor (wie z.B. VirtualBox) steht im Konflikt mit KVM. Bitte stoppen Sie den anderen Hypervisor oder verwenden Sie --driver um den Hypervisor zu wechseln.",
 	"Another minikube instance is downloading dependencies... ": "Eine andere Minikube-Instanz lädt Abhängigkeiten herunter... ",
 	"Another program is using a file required by minikube. If you are using Hyper-V, try stopping the minikube VM from within the Hyper-V manager": "Ein anderes Programm benutzt eine Datei, die Minikube benötigt. Wenn Sie Hyper-V verwenden, versuchen Sie die minikube VM aus dem Hyper-V Manager heraus zu stoppen",
+	"Another tunnel process is already running, terminate the existing instance to start a new one": "",
 	"At least needs control plane nodes to enable addon": "Benötige mindestens Control Plane Nodes um das Addon zu aktivieren",
 	"Auto-pause is already enabled.": "",
 	"Automatically selected the {{.driver}} driver": "Treiber {{.driver}} wurde automatisch ausgewählt",
@@ -957,6 +958,7 @@
 	"error: --output must be 'text', 'yaml' or 'json'": "Fehler: --output muss entweder 'text', 'yaml' oder 'json' sein",
 	"error: --output must be 'yaml' or 'json'": "Fehler: --output muss entweder 'yaml' oder 'json' sein",
 	"experimental": "experimentell",
+	"failed to acquire lock due to unexpected error": "",
 	"failed to add node": "Hinzufügen des Nodes fehlgeschlagen",
 	"failed to open browser: {{.error}}": "Öffnen des Browsers fehlgeschlagen: {{.error}}",
 	"failed to save config": "Speichern der Konfiguration fehlgeschlagen",

translations/es.json

@@ -73,6 +73,7 @@
 	"Another hypervisor, such as VirtualBox, is conflicting with KVM. Please stop the other hypervisor, or use --driver to switch to it.": "Otro hipervisor, por ejemplo VirtualBox, está en conflicto con KVM. Por favor detén el otro hipervisor, o usa --driver para cambiarlo.",
 	"Another minikube instance is downloading dependencies... ": "Otra instancia de minikube esta descargando dependencias...",
 	"Another program is using a file required by minikube. If you are using Hyper-V, try stopping the minikube VM from within the Hyper-V manager": "Otro programa está usando un archivo requerido por minikube. Si estas usando Hyper-V, intenta detener la máquina virtual de minikube desde el administrador de Hyper-V",
+	"Another tunnel process is already running, terminate the existing instance to start a new one": "",
 	"At least needs control plane nodes to enable addon": "Al menos se necesita un nodo de plano de control para habilitar el addon",
 	"Auto-pause is already enabled.": "",
 	"Automatically selected the {{.driver}} driver": "Controlador {{.driver}} seleccionado automáticamente",
@@ -954,6 +955,7 @@
 	"error: --output must be 'text', 'yaml' or 'json'": "",
 	"error: --output must be 'yaml' or 'json'": "",
 	"experimental": "",
+	"failed to acquire lock due to unexpected error": "",
 	"failed to add node": "",
 	"failed to open browser: {{.error}}": "",
 	"failed to save config": "",

translations/fr.json

@@ -73,6 +73,7 @@
 	"Another hypervisor, such as VirtualBox, is conflicting with KVM. Please stop the other hypervisor, or use --driver to switch to it.": "Un autre hyperviseur, tel que VirtualBox, est en conflit avec KVM. Veuillez arrêter l'autre hyperviseur ou utiliser --driver pour y basculer.",
 	"Another minikube instance is downloading dependencies... ": "Une autre instance minikube télécharge des dépendances",
 	"Another program is using a file required by minikube. If you are using Hyper-V, try stopping the minikube VM from within the Hyper-V manager": "Un autre programme utilise un fichier requis par minikube. Si vous utilisez Hyper-V, essayez d'arrêter la machine virtuelle minikube à partir du gestionnaire Hyper-V",
+	"Another tunnel process is already running, terminate the existing instance to start a new one": "",
 	"At least needs control plane nodes to enable addon": "Nécessite au moins des nœuds de plan de contrôle pour activer le module",
 	"Auto-pause is already enabled.": "La pause automatique est déjà activée.",
 	"Automatically selected the {{.driver}} driver": "Choix automatique du pilote {{.driver}}",
@@ -936,6 +937,7 @@
 	"error: --output must be 'text', 'yaml' or 'json'": "erreur : --output doit être 'text', 'yaml' ou 'json'",
 	"error: --output must be 'yaml' or 'json'": "erreur : --output doit être 'yaml' ou 'json'",
 	"experimental": "expérimental",
+	"failed to acquire lock due to unexpected error": "",
 	"failed to add node": "échec de l'ajout du nœud",
 	"failed to open browser: {{.error}}": "échec de l'ouverture du navigateur : {{.error}}",
 	"failed to save config": "échec de l'enregistrement de la configuration",

translations/ja.json

@@ -67,6 +67,7 @@
 	"Another hypervisor, such as VirtualBox, is conflicting with KVM. Please stop the other hypervisor, or use --driver to switch to it.": "VirtualBox などの別のハイパーバイザーが、KVM と競合しています。他のハイパーバイザーを停止するか、--driver を使用して切り替えてください。",
 	"Another minikube instance is downloading dependencies... ": "別の minikube のインスタンスが、依存関係をダウンロードしています... ",
 	"Another program is using a file required by minikube. If you are using Hyper-V, try stopping the minikube VM from within the Hyper-V manager": "別のプログラムが、minikube に必要なファイルを使用しています。Hyper-V を使用している場合は、Hyper-V マネージャー内から minikube VM を停止してみてください",
+	"Another tunnel process is already running, terminate the existing instance to start a new one": "",
 	"At least needs control plane nodes to enable addon": "アドオンを有効にするには、少なくともコントロールプレーンノードが必要です",
 	"Auto-pause is already enabled.": "自動一時停止は既に有効になっています。",
 	"Automatically selected the {{.driver}} driver": "{{.driver}} ドライバーが自動的に選択されました",
@@ -894,6 +895,7 @@
 	"error: --output must be 'text', 'yaml' or 'json'": "エラー: --output は 'text'、'yaml'、'json' のいずれかでなければなりません",
 	"error: --output must be 'yaml' or 'json'": "エラー: --output は 'yaml'、'json' のいずれかでなければなりません",
 	"experimental": "実験的",
+	"failed to acquire lock due to unexpected error": "",
 	"failed to add node": "ノード追加に失敗しました",
 	"failed to open browser: {{.error}}": "ブラウザー起動に失敗しました: {{.error}}",
 	"failed to save config": "設定保存に失敗しました",

translations/ko.json

@@ -75,6 +75,7 @@
 	"Another hypervisor, such as VirtualBox, is conflicting with KVM. Please stop the other hypervisor, or use --driver to switch to it.": "VirtualBox 와 같은 또 다른 하이퍼바이저가 KVM 과 충돌이 발생합니다. 다른 하이퍼바이저를 중단하거나 --driver 로 변경하세요",
 	"Another minikube instance is downloading dependencies... ": "",
 	"Another program is using a file required by minikube. If you are using Hyper-V, try stopping the minikube VM from within the Hyper-V manager": "",
+	"Another tunnel process is already running, terminate the existing instance to start a new one": "",
 	"At least needs control plane nodes to enable addon": "",
 	"Auto-pause is already enabled.": "자동 일시 정지 설정이 이미 활성화되어있습니다",
 	"Automatically selected the {{.driver}} driver": "자동적으로 {{.driver}} 드라이버가 선택되었습니다",
@@ -957,6 +958,7 @@
 	"error: --output must be 'text', 'yaml' or 'json'": "",
 	"error: --output must be 'yaml' or 'json'": "",
 	"experimental": "",
+	"failed to acquire lock due to unexpected error": "",
 	"failed to add node": "",
 	"failed to open browser: {{.error}}": "",
 	"failed to save config": "",

translations/pl.json

@@ -73,6 +73,7 @@
 	"Another hypervisor, such as VirtualBox, is conflicting with KVM. Please stop the other hypervisor, or use --driver to switch to it.": "Inny hiperwizor, taki jak Virtualbox, powoduje konflikty z KVM. Zatrzymaj innego hiperwizora lub użyj flagi --driver żeby go zmienić.",
 	"Another minikube instance is downloading dependencies... ": "Inny program minikube już pobiera zależności...",
 	"Another program is using a file required by minikube. If you are using Hyper-V, try stopping the minikube VM from within the Hyper-V manager": "Inny program używa pliku wymaganego przez minikube. Jeśli używasz Hyper-V, spróbuj zatrzymać maszynę wirtualną minikube z poziomu managera Hyper-V",
+	"Another tunnel process is already running, terminate the existing instance to start a new one": "",
 	"At least needs control plane nodes to enable addon": "Wymaga węzłów z płaszczyzny kontrolnej do włączenia addona",
 	"Auto-pause is already enabled.": "",
 	"Automatically selected the {{.driver}} driver": "Automatycznie wybrano sterownik {{.driver}}",
@@ -966,6 +967,7 @@
 	"error: --output must be 'text', 'yaml' or 'json'": "",
 	"error: --output must be 'yaml' or 'json'": "",
 	"experimental": "",
+	"failed to acquire lock due to unexpected error": "",
 	"failed to add node": "",
 	"failed to open browser: {{.error}}": "Nie udało się otworzyć przeglądarki: {{.error}}",
 	"failed to save config": "",

translations/ru.json

@@ -65,6 +65,7 @@
 	"Another hypervisor, such as VirtualBox, is conflicting with KVM. Please stop the other hypervisor, or use --driver to switch to it.": "",
 	"Another minikube instance is downloading dependencies... ": "",
 	"Another program is using a file required by minikube. If you are using Hyper-V, try stopping the minikube VM from within the Hyper-V manager": "",
+	"Another tunnel process is already running, terminate the existing instance to start a new one": "",
 	"At least needs control plane nodes to enable addon": "",
 	"Auto-pause is already enabled.": "",
 	"Automatically selected the {{.driver}} driver": "",
@@ -886,6 +887,7 @@
 	"error: --output must be 'text', 'yaml' or 'json'": "",
 	"error: --output must be 'yaml' or 'json'": "",
 	"experimental": "",
+	"failed to acquire lock due to unexpected error": "",
 	"failed to add node": "",
 	"failed to open browser: {{.error}}": "",
 	"failed to save config": "",

translations/strings.txt

@@ -65,6 +65,7 @@
 	"Another hypervisor, such as VirtualBox, is conflicting with KVM. Please stop the other hypervisor, or use --driver to switch to it.": "",
 	"Another minikube instance is downloading dependencies... ": "",
 	"Another program is using a file required by minikube. If you are using Hyper-V, try stopping the minikube VM from within the Hyper-V manager": "",
+	"Another tunnel process is already running, terminate the existing instance to start a new one": "",
 	"At least needs control plane nodes to enable addon": "",
 	"Auto-pause is already enabled.": "",
 	"Automatically selected the {{.driver}} driver": "",
@@ -886,6 +887,7 @@
 	"error: --output must be 'text', 'yaml' or 'json'": "",
 	"error: --output must be 'yaml' or 'json'": "",
 	"experimental": "",
+	"failed to acquire lock due to unexpected error": "",
 	"failed to add node": "",
 	"failed to open browser: {{.error}}": "",
 	"failed to save config": "",

translations/zh-CN.json

@@ -84,6 +84,7 @@
 	"Another hypervisor, such as VirtualBox, is conflicting with KVM. Please stop the other hypervisor, or use --vm-driver to switch to it.": "另外一个管理程序与 KVM 产生了冲突，如 VirtualBox。请停止其他的管理程序",
 	"Another minikube instance is downloading dependencies... ": "",
 	"Another program is using a file required by minikube. If you are using Hyper-V, try stopping the minikube VM from within the Hyper-V manager": "",
+	"Another tunnel process is already running, terminate the existing instance to start a new one": "",
 	"At least needs control plane nodes to enable addon": "",
 	"Auto-pause is already enabled.": "",
 	"Automatically selected the '{{.driver}}' driver": "自动选择 '{{.driver}}' 驱动",
@@ -1074,6 +1075,7 @@
 	"error: --output must be 'text', 'yaml' or 'json'": "",
 	"error: --output must be 'yaml' or 'json'": "",
 	"experimental": "",
+	"failed to acquire lock due to unexpected error": "",
 	"failed to add node": "",
 	"failed to open browser: {{.error}}": "",
 	"failed to save config": "",