fix manifest tag index in manifest.go (#731)

Co-authored-by: Simon Aronsson <simme@arcticbit.se>

pkg/registry/manifest/manifest.go

@@ -20,7 +20,7 @@ func BuildManifestURL(container types.Container) (string, error) {
 	}
 
 	host, err := helpers.NormalizeRegistry(normalizedName.String())
-	img, tag := extractImageAndTag(strings.TrimPrefix(container.ImageName(), host+"/"))
+	img, tag := ExtractImageAndTag(strings.TrimPrefix(container.ImageName(), host+"/"))
 
 	logrus.WithFields(logrus.Fields{
 		"image":      img,
@@ -45,15 +45,16 @@ func BuildManifestURL(container types.Container) (string, error) {
 	return url.String(), nil
 }
 
-func extractImageAndTag(imageName string) (string, string) {
+// ExtractImageAndTag from a concatenated string
+func ExtractImageAndTag(imageName string) (string, string) {
 	var img string
 	var tag string
 
 	if strings.Contains(imageName, ":") {
 		parts := strings.Split(imageName, ":")
 		if len(parts) > 2 {
-			img = fmt.Sprintf("%s%s", parts[0], parts[1])
-			tag = parts[3]
+			img = parts[0]
+			tag = strings.Join(parts[1:], ":")
 		} else {
 			img = parts[0]
 			tag = parts[1]

pkg/registry/manifest/manifest_test.go

@@ -61,6 +61,15 @@ var _ = Describe("the manifest module", func() {
 			Expect(err).NotTo(HaveOccurred())
 			Expect(res).To(Equal(expected))
 		})
+		It("should combine the tag name and digest pinning into one digest, given multiple colons", func() {
+			in := "containrrr/watchtower:latest@sha256:daf7034c5c89775afe3008393ae033529913548243b84926931d7c84398ecda7"
+			image, tag := "containrrr/watchtower", "latest@sha256:daf7034c5c89775afe3008393ae033529913548243b84926931d7c84398ecda7"
+
+			imageOut, tagOut := manifest.ExtractImageAndTag(in)
+
+			Expect(imageOut).To(Equal(image))
+			Expect(tagOut).To(Equal(tag))
+		})
 	})
 
 })