Added noUpdate run parameter, just pull new image without updating container

actions/update.go

@@ -34,7 +34,7 @@ func containerFilter(names []string) container.Filter {
 // used to start those containers have been updated. If a change is detected in
 // any of the images, the associated containers are stopped and restarted with
 // the new image.
-func Update(client container.Client, names []string, cleanup bool, noRestart bool) error {
+func Update(client container.Client, names []string, cleanup bool, noRestart bool, noUpdate bool) error {
 	log.Debug("Checking containers for updated images")
 
 	containers, err := client.ListContainers(containerFilter(names))
@@ -59,43 +59,45 @@ func Update(client container.Client, names []string, cleanup bool, noRestart boo
 
 	checkDependencies(containers)
 
-	// Stop stale containers in reverse order
+	if !noUpdate {
-	for i := len(containers) - 1; i >= 0; i-- {
+		// Stop stale containers in reverse order
-		container := containers[i]
+		for i := len(containers) - 1; i >= 0; i-- {
+			container := containers[i]
 
-		if container.IsWatchtower() {
-			continue
-		}
-
-		if container.Stale {
-			if err := client.StopContainer(container, waitTime); err != nil {
-				log.Error(err)
-			}
-		}
-	}
-
-	// Restart stale containers in sorted order
-	for _, container := range containers {
-		if container.Stale {
-			// Since we can't shutdown a watchtower container immediately, we need to
-			// start the new one while the old one is still running. This prevents us
-			// from re-using the same container name so we first rename the current
-			// instance so that the new one can adopt the old name.
 			if container.IsWatchtower() {
-				if err := client.RenameContainer(container, randName()); err != nil {
+				continue
-					log.Error(err)
-					continue
-				}
 			}
 
-			if !noRestart {
+			if container.Stale {
-				if err := client.StartContainer(container); err != nil {
+				if err := client.StopContainer(container, waitTime); err != nil {
 					log.Error(err)
 				}
 			}
+		}
 
-			if cleanup {
+		// Restart stale containers in sorted order
-				client.RemoveImage(container)
+		for _, container := range containers {
+			if container.Stale {
+				// Since we can't shutdown a watchtower container immediately, we need to
+				// start the new one while the old one is still running. This prevents us
+				// from re-using the same container name so we first rename the current
+				// instance so that the new one can adopt the old name.
+				if container.IsWatchtower() {
+					if err := client.RenameContainer(container, randName()); err != nil {
+						log.Error(err)
+						continue
+					}
+				}
+
+				if !noRestart {
+					if err := client.StartContainer(container); err != nil {
+						log.Error(err)
+					}
+				}
+
+				if cleanup {
+					client.RemoveImage(container)
+				}
 			}
 		}
 	}

main.go

@@ -29,6 +29,7 @@ var (
 	scheduleSpec string
 	cleanup      bool
 	noRestart    bool
+	noUpdate	 bool
 	notifier     *notifications.Notifier
 )
 
@@ -76,6 +77,11 @@ func main() {
 			Usage:  "remove old images after updating",
 			EnvVar: "WATCHTOWER_CLEANUP",
 		},
+		cli.BoolFlag{
+			Name:   "no-update",
+			Usage:  "do not update container",
+			EnvVar: "WATCHTOWER_NO_UPDATE",
+		},
 		cli.BoolFlag{
 			Name:   "tlsverify",
 			Usage:  "use TLS and verify the remote",
@@ -146,6 +152,7 @@ func before(c *cli.Context) error {
 
 	cleanup = c.GlobalBool("cleanup")
 	noRestart = c.GlobalBool("no-restart")
+	noUpdate = c.GlobalBool("no-update")
 
 	// configure environment vars for client
 	err := envConfig(c)
@@ -177,7 +184,7 @@ func start(c *cli.Context) error {
 			case v := <- tryLockSem:
 				defer func() { tryLockSem <- v }()
 				notifier.StartNotification()
-				if err := actions.Update(client, names, cleanup, noRestart); err != nil {
+				if err := actions.Update(client, names, cleanup, noRestart, noUpdate); err != nil {
 					log.Println(err)
 				}
 				notifier.SendNotification()