Add support for setting the name while keeping the digest

- And the other way around

Issue: #3487

kustomize/internal/commands/edit/set/setimage.go

@@ -140,6 +140,11 @@ func (o *setImageOptions) RunSetImage(fSys filesys.FileSystem) error {
 				argIm = replaceNewTag(argIm, im.NewTag)
 			}
 
+			// Reuse the existing digest when asterisk disgest is passed
+			if argIm.Digest == preserveSeparator {
+				argIm = replaceDigest(argIm, im.Digest)
+			}
+
 			o.imageMap[im.Name] = argIm
 
 			continue
@@ -159,6 +164,10 @@ func (o *setImageOptions) RunSetImage(fSys filesys.FileSystem) error {
 			v = replaceNewTag(v, "")
 		}
 
+		if v.Digest == preserveSeparator {
+			v = replaceDigest(v, "")
+		}
+
 		images = append(images, v)
 	}
 
@@ -188,6 +197,15 @@ func replaceNewTag(image types.Image, newTag string) types.Image {
 	}
 }
 
+func replaceDigest(image types.Image, digest string) types.Image {
+	return types.Image{
+		Name:    image.Name,
+		NewName: image.NewName,
+		NewTag:  image.NewTag,
+		Digest:  digest,
+	}
+}
+
 func parse(arg string) (types.Image, error) {
 
 	// matches if there is an image name to overwrite

kustomize/internal/commands/edit/set/setimage_test.go

@@ -349,6 +349,63 @@ func TestSetImage(t *testing.T) {
 					"  newName: my-image1",
 				}},
 		},
+		{
+			description: "keep new name and update digest",
+			given: given{
+				args: []string{"image2=*@sha256:24a0c4b4a4c0eb97a1aabb8e29f18e917d05abfe1b7a7c07857230879ce7d3d3"},
+				infileImages: []string{
+					"images:",
+					"- name: image2",
+					"  newName: my-image2",
+					"  digest: sha256:abcdef12345",
+				},
+			},
+			expected: expected{
+				fileOutput: []string{
+					"images:",
+					"- digest: sha256:24a0c4b4a4c0eb97a1aabb8e29f18e917d05abfe1b7a7c07857230879ce7d3d3",
+					"  name: image2",
+					"  newName: my-image2",
+				}},
+		},
+		{
+			description: "keep new name, remove tag, and set digest",
+			given: given{
+				args: []string{"image2=*@sha256:24a0c4b4a4c0eb97a1aabb8e29f18e917d05abfe1b7a7c07857230879ce7d3d3"},
+				infileImages: []string{
+					"images:",
+					"- name: image2",
+					"  newName: my-image2",
+					"  newTag: my-tag",
+				},
+			},
+			expected: expected{
+				fileOutput: []string{
+					"images:",
+					"- digest: sha256:24a0c4b4a4c0eb97a1aabb8e29f18e917d05abfe1b7a7c07857230879ce7d3d3",
+					"  name: image2",
+					"  newName: my-image2",
+				}},
+		},
+		{
+			description: "update new name and keep the digest",
+			given: given{
+				args: []string{"image2=my-image2@*"},
+				infileImages: []string{
+					"images:",
+					"- digest: sha256:24a0c4b4a4c0eb97a1aabb8e29f18e917d05abfe1b7a7c07857230879ce7d3d3",
+					"  name: image2",
+					"  newName: foo.bar.foo:8800/foo/image1",
+				},
+			},
+			expected: expected{
+				fileOutput: []string{
+					"images:",
+					"- digest: sha256:24a0c4b4a4c0eb97a1aabb8e29f18e917d05abfe1b7a7c07857230879ce7d3d3",
+					"  name: image2",
+					"  newName: my-image2",
+				}},
+		},
 	}
 
 	for _, tc := range testCases {