Add a tag-only flag to publisher.

pkg/commands/options/tags.go

@@ -20,10 +20,13 @@ import (
 
 // TagsOptions holds the list of tags to tag the built image
 type TagsOptions struct {
-	Tags []string
+	Tags    []string
+	TagOnly bool
 }
 
 func AddTagsArg(cmd *cobra.Command, ta *TagsOptions) {
 	cmd.Flags().StringSliceVarP(&ta.Tags, "tags", "t", []string{"latest"},
 		"Which tags to use for the produced image instead of the default 'latest' tag.")
+	cmd.Flags().BoolVar(&ta.TagOnly, "tag-only", false,
+		"Include tags but not digests in resolved image references. Useful when digests are not preserved when images are repopulated.")
 }

pkg/commands/resolver.go

@@ -134,6 +134,7 @@ func makePublisher(no *options.NameOptions, lo *options.LocalOptions, ta *option
 			publish.WithAuthFromKeychain(authn.DefaultKeychain),
 			publish.WithNamer(namer),
 			publish.WithTags(ta.Tags),
+			publish.WithTagOnly(ta.TagOnly),
 			publish.Insecure(lo.InsecureRegistry))
 	}()
 	if err != nil {

pkg/publish/default.go

@@ -15,6 +15,7 @@
 package publish
 
 import (
+	"errors"
 	"fmt"
 	"log"
 	"net/http"
@@ -33,6 +34,7 @@ type defalt struct {
 	auth     authn.Authenticator
 	namer    Namer
 	tags     []string
+	tagOnly  bool
 	insecure bool
 }
 
@@ -45,6 +47,7 @@ type defaultOpener struct {
 	auth     authn.Authenticator
 	namer    Namer
 	tags     []string
+	tagOnly  bool
 	insecure bool
 }
 
@@ -63,12 +66,22 @@ func identity(in string) string { return in }
 var defaultTags = []string{"latest"}
 
 func (do *defaultOpener) Open() (Interface, error) {
+	if do.tagOnly {
+		if len(do.tags) != 1 {
+			return nil, errors.New("must specify exactly one tag to resolve images into tag-only references")
+		}
+		if do.tags[0] == defaultTags[0] {
+			return nil, errors.New("latest tag cannot be used in tag-only references")
+		}
+	}
+
 	return &defalt{
 		base:     do.base,
 		t:        do.t,
 		auth:     do.auth,
 		namer:    do.namer,
 		tags:     do.tags,
+		tagOnly:  do.tagOnly,
 		insecure: do.insecure,
 	}, nil
 }
@@ -123,6 +136,15 @@ func (d *defalt) Publish(img v1.Image, s string) (name.Reference, error) {
 		}
 	}
 
+	if d.tagOnly {
+		// We already validated that there is a single tag tag (not latest).
+		tag, err := name.NewTag(fmt.Sprintf("%s/%s:%s", d.base, d.namer(s), d.tags[0]))
+		if err != nil {
+			return nil, err
+		}
+		return &tag, nil
+	}
+
 	h, err := img.Digest()
 	if err != nil {
 		return nil, err

pkg/publish/default_test.go

@@ -291,4 +291,25 @@ func TestDefaultWithReleaseTag(t *testing.T) {
 	if _, ok := createdTags["v1.2.3"]; !ok {
 		t.Errorf("Tag v1.2.3 was not created.")
 	}
+
+	for tag := range createdTags {
+		delete(createdTags, tag)
+	}
+
+	def, err = NewDefault(repoName, WithTags([]string{releaseTag}), WithTagOnly(true))
+	if err != nil {
+		t.Errorf("NewDefault() = %v", err)
+	}
+	if d, err := def.Publish(img, importpath); err != nil {
+		t.Errorf("Publish() = %v", err)
+	} else if !strings.HasPrefix(d.String(), repoName) {
+		t.Errorf("Publish() = %v, wanted prefix %v", d, tag.Repository)
+	} else if !strings.HasSuffix(d.Context().String(), strings.ToLower(importpath)) {
+		t.Errorf("Publish() = %v, wanted suffix %v", d.Context(), md5Hash(importpath))
+	} else if !strings.Contains(d.String(), releaseTag) {
+		t.Errorf("Publish() = %v, wanted tag included: %v", d.String(), releaseTag)
+	} else if strings.Contains(d.String(), "@sha256:") {
+		t.Errorf("Publish() = %v, wanted no digest", d.String())
+	}
+
 }

pkg/publish/options.go

@@ -86,6 +86,14 @@ func WithTags(tags []string) Option {
 	}
 }
 
+// WithTagOnly is a functional option for resolving images into tag-only references
+func WithTagOnly(tagOnly bool) Option {
+	return func(i *defaultOpener) error {
+		i.tagOnly = tagOnly
+		return nil
+	}
+}
+
 func Insecure(b bool) Option {
 	return func(i *defaultOpener) error {
 		i.insecure = b