Adding --label flag to pack builder create command

internal/builder/builder.go

@@ -103,6 +103,7 @@
 
 type options struct {
 	toFlatten buildpack.FlattenModuleInfos
+	labels    map[string]string
 }
 
 // FromImage constructs a builder from a builder image
@@ -139,6 +140,13 @@
 		return nil, err
 	}
 
+	for labelKey, labelValue := range opts.labels {
+		err = img.SetLabel(labelKey, labelValue)
+		if err != nil {
+			return nil, errors.Wrapf(err, "adding label %s=%s", labelKey, labelValue)
+		}
+	}
+
 	bldr := &Builder{
 		baseImageName:        img.Name(),
 		image:                img,
@@ -170,6 +178,13 @@
 	}
 }
 
+func WithLabels(labels map[string]string) BuilderOption {
+	return func(o *options) error {
+		o.labels = labels
+		return nil
+	}
+}
+
 func constructLifecycleDescriptor(metadata Metadata) LifecycleDescriptor {
 	return CompatDescriptor(LifecycleDescriptor{
 		Info: LifecycleInfo{

internal/builder/builder_test.go

@@ -1939,6 +1939,34 @@ func testBuilder(t *testing.T, when spec.G, it spec.S) {
 			})
 		})
 	})
+
+	when("labels", func() {
+		var (
+			customLabels, imageLabels map[string]string
+			err                       error
+		)
+		it.Before(func() {
+			h.AssertNil(t, baseImage.SetEnv("CNB_USER_ID", "1234"))
+			h.AssertNil(t, baseImage.SetEnv("CNB_GROUP_ID", "4321"))
+			h.AssertNil(t, baseImage.SetLabel("io.buildpacks.stack.id", "some.stack.id"))
+			h.AssertNil(t, baseImage.SetLabel("io.buildpacks.stack.mixins", `["mixinX", "mixinY", "build:mixinA"]`))
+		})
+
+		it.After(func() {
+			h.AssertNilE(t, baseImage.Cleanup())
+		})
+
+		it("should set labels to the image", func() {
+			customLabels = map[string]string{"test.label.one": "1", "test.label.two": "2"}
+			subject, err = builder.New(baseImage, "some/builder", builder.WithLabels(customLabels))
+			h.AssertNil(t, err)
+
+			imageLabels, err = baseImage.Labels()
+			h.AssertNil(t, err)
+			h.AssertEq(t, imageLabels["test.label.one"], "1")
+			h.AssertEq(t, imageLabels["test.label.two"], "2")
+		})
+	})
 }
 
 func assertImageHasBPLayer(t *testing.T, image *fakes.Image, bp buildpack.BuildModule) {

internal/commands/builder_create.go

@@ -23,6 +23,7 @@ type BuilderCreateFlags struct {
 	Registry        string
 	Policy          string
 	Flatten         []string
+	Label           map[string]string
 }
 
 // CreateBuilder creates a builder image, based on a builder config
@@ -96,6 +97,7 @@ Creating a custom builder allows you to control what buildpacks are used and wha
 				Registry:        flags.Registry,
 				PullPolicy:      pullPolicy,
 				Flatten:         toFlatten,
+				Labels:          flags.Label,
 			}); err != nil {
 				return err
 			}
@@ -113,6 +115,7 @@ Creating a custom builder allows you to control what buildpacks are used and wha
 	cmd.Flags().BoolVar(&flags.Publish, "publish", false, "Publish the builder directly to the container registry specified in <image-name>, instead of the daemon.")
 	cmd.Flags().StringVar(&flags.Policy, "pull-policy", "", "Pull policy to use. Accepted values are always, never, and if-not-present. The default is always")
 	cmd.Flags().StringSliceVar(&flags.Flatten, "flatten", nil, "List of buildpacks to flatten together into a single layer (format: '<buildpack-id>@<buildpack-version>,<buildpack-id>@<buildpack-version>'")
+	cmd.Flags().StringToStringVarP(&flags.Label, "label", "l", nil, "Labels to add to the builder image, in the form of '<name>=<value>'")
 
 	AddHelpFlag(cmd, "create")
 	return cmd

internal/commands/builder_create_test.go

@@ -424,5 +424,22 @@ func testCreateCommand(t *testing.T, when spec.G, it spec.S) {
 				})
 			})
 		})
+
+		when("--label", func() {
+			when("can not be parsed", func() {
+				it("errors with a descriptive message", func() {
+					cmd := packageCommand()
+					cmd.SetArgs([]string{
+						"some/builder",
+						"--config", builderConfigPath,
+						"--label", "name+value",
+					})
+
+					err := cmd.Execute()
+					h.AssertNotNil(t, err)
+					h.AssertError(t, err, "invalid argument \"name+value\" for \"-l, --label\" flag: name+value must be formatted as key=value")
+				})
+			})
+		})
 	})
 }

pkg/client/create_builder.go

@@ -32,6 +32,9 @@ type CreateBuilderOptions struct {
 	// BuildConfigEnv for Builder
 	BuildConfigEnv map[string]string
 
+	// Map of labels to add to the Buildpack
+	Labels map[string]string
+
 	// Configuration that defines the functionality a builder provides.
 	Config pubbldr.Config
 
@@ -154,6 +157,10 @@ func (c *Client) createBaseBuilder(ctx context.Context, opts CreateBuilderOption
 	if opts.Flatten != nil && len(opts.Flatten.FlattenModules()) > 0 {
 		builderOpts = append(builderOpts, builder.WithFlattened(opts.Flatten))
 	}
+	if opts.Labels != nil && len(opts.Labels) > 0 {
+		builderOpts = append(builderOpts, builder.WithLabels(opts.Labels))
+	}
+
 	bldr, err := builder.New(baseImage, opts.BuilderName, builderOpts...)
 	if err != nil {
 		return nil, errors.Wrap(err, "invalid build-image")

pkg/client/create_builder_test.go

@@ -791,6 +791,20 @@ func testCreateBuilder(t *testing.T, when spec.G, it spec.S) {
 				h.AssertNotContains(t, out.String(), "is using deprecated Buildpacks API version")
 			})
 
+			it("should set labels", func() {
+				opts.Labels = map[string]string{"test.label.one": "1", "test.label.two": "2"}
+				prepareFetcherWithBuildImage()
+				prepareFetcherWithRunImages()
+
+				err := subject.CreateBuilder(context.TODO(), opts)
+				h.AssertNil(t, err)
+
+				imageLabels, err := fakeBuildImage.Labels()
+				h.AssertNil(t, err)
+				h.AssertEq(t, imageLabels["test.label.one"], "1")
+				h.AssertEq(t, imageLabels["test.label.two"], "2")
+			})
+
 			when("Buildpack dependencies are provided", func() {
 				var (
 					bp1v1          buildpack.BuildModule