add Extensions (no DetectionOrder yet)

internal/builder/inspect.go

@@ -22,6 +22,7 @@ type Info struct {
 	BuildpackLayers dist.ModuleLayers
 	Lifecycle       LifecycleDescriptor
 	CreatedBy       CreatorMetadata
+	Extensions      []dist.ModuleInfo
 }
 
 type Inspectable interface {
@@ -127,6 +128,7 @@ func (i *Inspector) Inspect(name string, daemon bool, orderDetectionDepth int) (
 		BuildpackLayers: layers,
 		Lifecycle:       lifecycle,
 		CreatedBy:       metadata.CreatedBy,
+		Extensions:      metadata.Extensions,
 	}, nil
 }
 

internal/builder/writer/human_readable.go

@@ -27,6 +27,7 @@ const (
 	writerMinWidth     = 0
 	writerTabWidth     = 0
 	buildpacksTabWidth = 8
+	extensionsTabWidth = 8
 	defaultTabWidth    = 4
 	writerPadChar      = ' '
 	writerFlags        = 0
@@ -59,7 +60,8 @@ Stack:
 {{ .Lifecycle }}
 {{ .RunImages }}
 {{ .Buildpacks }}
-{{ .Order }}`
+{{ .Order }}
+{{ .Extensions }}`
 )
 
 type HumanReadable struct{}
@@ -132,10 +134,16 @@ func writeBuilderInfo(
 	}
 	lifecycleString, lifecycleWarnings := lifecycleOutput(info.Lifecycle, sharedInfo.Name)
 
+	extensionsString, extensionsWarnings, err := extensionsOutput(info.Extensions, sharedInfo.Name)
+	if err != nil {
+		return fmt.Errorf("compiling extensions output: %w", err)
+	}
+
 	warnings = append(warnings, runImagesWarnings...)
 	warnings = append(warnings, orderWarnings...)
 	warnings = append(warnings, buildpacksWarnings...)
 	warnings = append(warnings, lifecycleWarnings...)
+	warnings = append(warnings, extensionsWarnings...)
 
 	outputTemplate, _ := template.New("").Parse(outputTemplate)
 	err = outputTemplate.Execute(
@@ -148,6 +156,7 @@ func writeBuilderInfo(
 			Order      string
 			Trusted    string
 			Lifecycle  string
+			Extensions string
 		}{
 			*info,
 			logger.IsVerbose(),
@@ -156,6 +165,7 @@ func writeBuilderInfo(
 			orderString,
 			stringFromBool(sharedInfo.Trusted),
 			lifecycleString,
+			extensionsString,
 		},
 	)
 
@@ -273,6 +283,47 @@ func writeLocalMirrors(logWriter io.Writer, runImage string, localRunImages []co
 	return nil
 }
 
+func extensionsOutput(extensions []dist.ModuleInfo, builderName string) (string, []string, error) {
+	output := "Extensions:\n"
+
+	if len(extensions) == 0 {
+		warnings := []string{
+			fmt.Sprintf("%s has no buildpacks", builderName),
+			"",
+		}
+
+		return fmt.Sprintf("%s  %s\n", output, none), warnings, nil
+	}
+
+	var (
+		tabWriterBuf         = bytes.Buffer{}
+		spaceStrippingWriter = &trailingSpaceStrippingWriter{
+			output: &tabWriterBuf,
+		}
+		extensionsTabWriter = tabwriter.NewWriter(spaceStrippingWriter, writerMinWidth, writerPadChar, buildpacksTabWidth, writerPadChar, writerFlags)
+	)
+
+	_, err := fmt.Fprint(extensionsTabWriter, "  ID\tNAME\tVERSION\tHOMEPAGE\n")
+	if err != nil {
+		return "", []string{}, fmt.Errorf("writing to tab writer: %w", err)
+	}
+
+	for _, b := range extensions {
+		_, err = fmt.Fprintf(extensionsTabWriter, "  %s\t%s\t%s\t%s\n", b.ID, strs.ValueOrDefault(b.Name, "-"), b.Version, strs.ValueOrDefault(b.Homepage, "-"))
+		if err != nil {
+			return "", []string{}, fmt.Errorf("writing to tab writer: %w", err)
+		}
+	}
+
+	err = extensionsTabWriter.Flush()
+	if err != nil {
+		return "", []string{}, fmt.Errorf("flushing tab writer: %w", err)
+	}
+
+	output += tabWriterBuf.String()
+	return output, []string{}, nil
+}
+
 func buildpacksOutput(buildpacks []dist.ModuleInfo, builderName string) (string, []string, error) {
 	output := "Buildpacks:\n"
 

internal/builder/writer/human_readable_test.go

@@ -86,6 +86,14 @@ Detection Order:
  │  │           └ test.bp.one@test.bp.one.version    (optional)[cyclic]
  │  └ test.bp.two@test.bp.two.version                (optional)
  └ test.bp.three@test.bp.three.version
+
+Extensions:
+  ID                     NAME        VERSION                        HOMEPAGE
+  test.top.nested        -           test.top.nested.version        -
+  test.nested            -                                          http://geocities.com/top-bp
+  test.bp.one            -           test.bp.one.version            http://geocities.com/cool-bp
+  test.bp.two            -           test.bp.two.version            -
+  test.bp.three          -           test.bp.three.version          -
 `
 
 		expectedLocalOutput = `
@@ -139,6 +147,14 @@ Detection Order:
  │  │           └ test.bp.one@test.bp.one.version    (optional)[cyclic]
  │  └ test.bp.two@test.bp.two.version                (optional)
  └ test.bp.three@test.bp.three.version
+
+Extensions:
+  ID                     NAME        VERSION                        HOMEPAGE
+  test.top.nested        -           test.top.nested.version        -
+  test.nested            -                                          http://geocities.com/top-bp
+  test.bp.one            -           test.bp.one.version            http://geocities.com/cool-bp
+  test.bp.two            -           test.bp.two.version            -
+  test.bp.three          -           test.bp.three.version          -
 `
 		expectedVerboseStack = `
 Stack:
@@ -185,6 +201,7 @@ REMOTE:
 				RunImageMirrors: []string{"first/default", "second/default"},
 				Buildpacks:      buildpacks,
 				Order:           order,
+				Extensions:      buildpacks,
 				BuildpackLayers: dist.ModuleLayers{},
 				Lifecycle: builder.LifecycleDescriptor{
 					Info: builder.LifecycleInfo{
@@ -217,6 +234,7 @@ REMOTE:
 				RunImageMirrors: []string{"first/local-default", "second/local-default"},
 				Buildpacks:      buildpacks,
 				Order:           order,
+				Extensions:      buildpacks,
 				BuildpackLayers: dist.ModuleLayers{},
 				Lifecycle: builder.LifecycleDescriptor{
 					Info: builder.LifecycleInfo{

pkg/client/inspect_builder.go

@@ -48,6 +48,10 @@ type BuilderInfo struct {
 	// Name and Version information from tooling used
 	// to produce this builder.
 	CreatedBy builder.CreatorMetadata
+
+	// Extension (metadata?) included with builder image
+	// to be displayed in cmd line
+	Extensions []dist.ModuleInfo
 }
 
 // BuildpackInfoKey contains all information needed to determine buildpack equivalence.
@@ -102,5 +106,6 @@ func (c *Client) InspectBuilder(name string, daemon bool, modifiers ...BuilderIn
 		BuildpackLayers: info.BuildpackLayers,
 		Lifecycle:       info.Lifecycle,
 		CreatedBy:       info.CreatedBy,
+		Extensions:      info.Extensions,
 	}, nil
 }