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))
@@ -59,6 +59,7 @@ func Update(client container.Client, names []string, cleanup bool, noRestart boo
 
 	checkDependencies(containers)
 
+	if !noUpdate {
 		// Stop stale containers in reverse order
 		for i := len(containers) - 1; i >= 0; i-- {
 			container := containers[i]
@@ -99,6 +100,7 @@ func Update(client container.Client, names []string, cleanup bool, noRestart boo
 				}
 			}
 		}
+	}
 
 	return nil
 }

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()