fix: always add missing slashes to link names (#1588)

internal/actions/update.go

@@ -2,7 +2,6 @@ package actions
 
 import (
 	"errors"
-	"strings"
 
 	"github.com/containrrr/watchtower/internal/util"
 	"github.com/containrrr/watchtower/pkg/container"
@@ -260,10 +259,6 @@ func UpdateImplicitRestart(containers []container.Container) {
 // container marked for restart
 func linkedContainerMarkedForRestart(links []string, containers []container.Container) string {
 	for _, linkName := range links {
-		// Since the container names need to start with '/', let's prepend it if it's missing
-		if !strings.HasPrefix(linkName, "/") {
-			linkName = "/" + linkName
-		}
 		for _, candidate := range containers {
 			if candidate.Name() == linkName && candidate.ToRestart() {
 				return linkName

pkg/container/container.go

@@ -160,7 +160,14 @@ func (c Container) Links() []string {
 	dependsOnLabelValue := c.getLabelValueOrEmpty(dependsOnLabel)
 
 	if dependsOnLabelValue != "" {
-		links := strings.Split(dependsOnLabelValue, ",")
+		for _, link := range strings.Split(dependsOnLabelValue, ",") {
+			// Since the container names need to start with '/', let's prepend it if it's missing
+			if !strings.HasPrefix(link, "/") {
+				link = "/" + link
+			}
+			links = append(links, link)
+		}
+
 		return links
 	}
 

pkg/container/container_test.go

@@ -178,14 +178,21 @@ var _ = Describe("the container", func() {
 						"com.centurylinklabs.watchtower.depends-on": "postgres",
 					}))
 					links := c.Links()
-					Expect(links).To(SatisfyAll(ContainElement("postgres"), HaveLen(1)))
+					Expect(links).To(SatisfyAll(ContainElement("/postgres"), HaveLen(1)))
 				})
 				It("should fetch depending containers if there are many", func() {
 					c = MockContainer(WithLabels(map[string]string{
 						"com.centurylinklabs.watchtower.depends-on": "postgres,redis",
 					}))
 					links := c.Links()
-					Expect(links).To(SatisfyAll(ContainElement("postgres"), ContainElement("redis"), HaveLen(2)))
+					Expect(links).To(SatisfyAll(ContainElement("/postgres"), ContainElement("/redis"), HaveLen(2)))
+				})
+				It("should only add slashes to names when they are missing", func() {
+					c = MockContainer(WithLabels(map[string]string{
+						"com.centurylinklabs.watchtower.depends-on": "/postgres,redis",
+					}))
+					links := c.Links()
+					Expect(links).To(SatisfyAll(ContainElement("/postgres"), ContainElement("/redis")))
 				})
 				It("should fetch depending containers if label is blank", func() {
 					c = MockContainer(WithLabels(map[string]string{