Implement support for digests in imageTags

This commit adds a new field to imageTags transformer
so that digests can be used instead of image tags if needed.

Closes https://github.com/kubernetes-sigs/kustomize/issues/326

docs/kustomization.yaml

@@ -247,8 +247,12 @@ vars:
 #      image: nginx:1.7.9
 #```
 # one can change the tag of myimage to v1 and the tag of nginx to 1.8.0 with the following:
+#
+# It also supports digests. If digest is present newTag is ignored.
 imageTags:
   - name: mycontainerregistry/myimage
     newTag: v1
   - name: nginx
     newTag: 1.8.0
+  - name: alpine
+    digest: sha256:24a0c4b4a4c0eb97a1aabb8e29f18e917d05abfe1b7a7c07857230879ce7d3d3

pkg/commands/setimagetag.go

@@ -20,6 +20,7 @@ import (
 	"errors"
 	"regexp"
 	"sort"
+	"strings"
 
 	"github.com/spf13/cobra"
 
@@ -29,7 +30,7 @@ import (
 )
 
 type setImageTagOptions struct {
-	imageTagMap map[string]string
+	imageTagMap map[string]types.ImageTag
 }
 
 var pattern = regexp.MustCompile("^(.*):([a-zA-Z0-9._-]*)$")
@@ -40,10 +41,10 @@ func newCmdSetImageTag(fsys fs.FileSystem) *cobra.Command {
 
 	cmd := &cobra.Command{
 		Use:   "imagetag",
-		Short: "Sets images and their new tags in the kustomization file",
+		Short: "Sets images and their new tags or digests in the kustomization file",
 		Example: `
 The command
-  set imagetag nginx:1.8.0 my-app:latest
+  set imagetag nginx:1.8.0 my-app:latest alpine@sha256:24a0c4b4a4c0eb97a1aabb8e29f18e917d05abfe1b7a7c07857230879ce7d3d3
 will add 
 
 imageTags:
@@ -51,9 +52,11 @@ imageTags:
   newTag: 1.8.0
 - name: my-app
   newTag: latest
+- name: alpine
+  digest: sha256:24a0c4b4a4c0eb97a1aabb8e29f18e917d05abfe1b7a7c07857230879ce7d3d3
 
 to the kustomization file if it doesn't exist,
-and overwrite the previous newTag if the image name exists.
+and overwrite the previous ones if the image tag exists.
 `,
 		RunE: func(cmd *cobra.Command, args []string) error {
 			err := o.Validate(args)
@@ -71,13 +74,27 @@ func (o *setImageTagOptions) Validate(args []string) error {
 	if len(args) == 0 {
 		return errors.New("no image and newTag specified")
 	}
-	o.imageTagMap = make(map[string]string)
+
+	o.imageTagMap = make(map[string]types.ImageTag)
+
 	for _, arg := range args {
+		if strings.Contains(arg, "@") {
+			img := strings.Split(arg, "@")
+			o.imageTagMap[img[0]] = types.ImageTag{
+				Name:   img[0],
+				Digest: img[1],
+			}
+			continue
+		}
+
 		imagetag := pattern.FindStringSubmatch(arg)
 		if len(imagetag) != 3 {
-			return errors.New("invalid format of imagetag, must specify it as <image>:<newtag>")
+			return errors.New("invalid format of imagetag, must specify it as <image>:<newtag> or <image>@<digest>")
+		}
+		o.imageTagMap[imagetag[1]] = types.ImageTag{
+			Name:   imagetag[1],
+			NewTag: imagetag[2],
 		}
-		o.imageTagMap[imagetag[1]] = imagetag[2]
 	}
 	return nil
 }
@@ -92,16 +109,18 @@ func (o *setImageTagOptions) RunSetImageTags(fsys fs.FileSystem) error {
 	if err != nil {
 		return err
 	}
-	imageTagMap := map[string]string{}
+
 	for _, it := range m.ImageTags {
-		imageTagMap[it.Name] = it.NewTag
+		if _, ok := o.imageTagMap[it.Name]; ok {
-	}
+			continue
-	for key, value := range o.imageTagMap {
+		}
-		imageTagMap[key] = value
+
+		o.imageTagMap[it.Name] = it
 	}
+
 	var imageTags []types.ImageTag
-	for key, value := range imageTagMap {
+	for _, v := range o.imageTagMap {
-		imageTags = append(imageTags, types.ImageTag{Name: key, NewTag: value})
+		imageTags = append(imageTags, v)
 	}
 	sort.Slice(imageTags, func(i, j int) bool {
 		return imageTags[i].Name < imageTags[j].Name

pkg/commands/setimagetag_test.go

@@ -29,7 +29,8 @@ func TestSetImageTagsHappyPath(t *testing.T) {
 	fakeFS.WriteFile(constants.KustomizationFileName, []byte(kustomizationContent))
 
 	cmd := newCmdSetImageTag(fakeFS)
-	args := []string{"image1:tag1", "image2:tag2", "localhost:5000/operator:1.0.0"}
+	args := []string{"image1:tag1", "image2:tag2", "localhost:5000/operator:1.0.0",
+		"foo.bar.baz:5000/one/two@sha256:24a0c4b4a4c0eb97a1aabb8e29f18e917d05abfe1b7a7c07857230879ce7d3d3"}
 	err := cmd.RunE(cmd, args)
 	if err != nil {
 		t.Errorf("unexpected cmd error: %v", err)
@@ -40,6 +41,8 @@ func TestSetImageTagsHappyPath(t *testing.T) {
 	}
 	expected := []byte(`
 imageTags:
+- digest: sha256:24a0c4b4a4c0eb97a1aabb8e29f18e917d05abfe1b7a7c07857230879ce7d3d3
+  name: foo.bar.baz:5000/one/two
 - name: image1
   newTag: tag1
 - name: image2

pkg/transformers/imagetag.go

@@ -18,7 +18,6 @@ package transformers
 
 import (
 	"regexp"
-	"strings"
 
 	"github.com/kubernetes-sigs/kustomize/pkg/resmap"
 	"github.com/kubernetes-sigs/kustomize/pkg/types"
@@ -83,7 +82,12 @@ func (pt *imageTagTransformer) updateContainers(obj map[string]interface{}, path
 		}
 		for _, imagetag := range pt.imageTags {
 			if isImageMatched(image.(string), imagetag.Name) {
-				container["image"] = strings.Join([]string{imagetag.Name, imagetag.NewTag}, ":")
+				container["image"] = imagetag.Name + ":" + imagetag.NewTag
+
+				if imagetag.Digest != "" {
+					container["image"] = imagetag.Name + "@" + imagetag.Digest
+				}
+
 				break
 			}
 		}

pkg/transformers/imagetag_test.go

@@ -50,6 +50,10 @@ func TestImageTagTransformer(t *testing.T) {
 									"name":  "nginx",
 									"image": "nginx:1.7.9",
 								},
+								map[string]interface{}{
+									"name":  "replaced-with-digest",
+									"image": "foobar:1",
+								},
 							},
 						},
 					},
@@ -114,6 +118,10 @@ func TestImageTagTransformer(t *testing.T) {
 									"name":  "nginx",
 									"image": "nginx:v2",
 								},
+								map[string]interface{}{
+									"name":  "replaced-with-digest",
+									"image": "foobar@sha256:24a0c4b4a4c0eb97a1aabb8e29f18e917d05abfe1b7a7c07857230879ce7d3d3",
+								},
 							},
 						},
 					},
@@ -160,6 +168,7 @@ func TestImageTagTransformer(t *testing.T) {
 		{Name: "nginx", NewTag: "v2"},
 		{Name: "my-nginx", NewTag: "previous"},
 		{Name: "myprivaterepohostname:1234/my/image", NewTag: "v1.0.1"},
+		{Name: "foobar", Digest: "sha256:24a0c4b4a4c0eb97a1aabb8e29f18e917d05abfe1b7a7c07857230879ce7d3d3"},
 	})
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)

pkg/types/kustomization.go

@@ -176,4 +176,8 @@ type ImageTag struct {
 
 	// NewTag is the value to use in replacing the original tag.
 	NewTag string `json:"newTag,omitempty" yaml:"newTag,omitempty"`
+
+	// Digest is the value used to replace the original image tag.
+	// If digest is present NewTag value is ignored.
+	Digest string `json:"digest,omitempty" yaml:"digest,omitempty"`
 }