Fix: order.toml has an order-ext table

buildpack/descriptor.go

@@ -61,23 +61,28 @@ func ReadGroup(path string) (Group, error) {
 	return group, err
 }
 
-func ReadOrder(path string) (Order, error) {
-	var order struct {
-		Order Order `toml:"order"`
+func ReadOrder(path string) (Order, Order, error) {
+	var order struct { // TODO: move this maybe
+		Order    Order `toml:"order"`
+		OrderExt Order `toml:"order-ext"`
 	}
 	_, err := toml.DecodeFile(path, &order)
-	return order.Order, err
+	return order.Order, order.OrderExt, err
 }
 
+// TODO: GroupElement is probably a better name for this
+// TODO: this struct is the amalgamation of all fields from order.toml & group.toml, which is a bit confusing and ties the code together in weird ways
+
 // A GroupBuildable represents a buildpack or extension referenced in a buildpack.toml's [[order.group]].
 // A GroupBuildable buildpack may be a regular buildpack, or a meta buildpack.
 type GroupBuildable struct {
-	API       string `toml:"api,omitempty" json:"-"`
-	Homepage  string `toml:"homepage,omitempty" json:"homepage,omitempty"`
+	API       string `toml:"api,omitempty" json:"-"`                       // group.toml
+	Homepage  string `toml:"homepage,omitempty" json:"homepage,omitempty"` // group.toml
 	ID        string `toml:"id" json:"id"`
 	Version   string `toml:"version" json:"version"`
-	Extension bool   `toml:"extension,omitempty" json:"extension,omitempty"` // TODO: check if this is okay, suggested to RFC
-	Optional  bool   `toml:"optional,omitempty" json:"optional,omitempty"`
+	Extension bool   `toml:"extension" json:"extension"`                   // group.toml
+	Optional  bool   `toml:"optional,omitempty" json:"optional,omitempty"` // order.toml
+	OrderExt  Order  `toml:"-" json:"-"`                                   // only for use by the Detector
 }
 
 func (b GroupBuildable) String() string {

buildpack/descriptor_test.go

@@ -42,7 +42,7 @@ func testDescriptor(t *testing.T, when spec.G, it spec.S) {
 					`group = [{id = "C"}, {}]`+"\n",
 				filepath.Join(tmpDir, "order.toml"),
 			)
-			actual, err := buildpack.ReadOrder(filepath.Join(tmpDir, "order.toml"))
+			actual, _, err := buildpack.ReadOrder(filepath.Join(tmpDir, "order.toml"))
 			if err != nil {
 				t.Fatalf("Unexpected error:\n%s\n", err)
 			}

cmd/lifecycle/detector.go

@@ -83,14 +83,43 @@ func (d *detectCmd) Exec() error {
 }
 
 func (da detectArgs) detect() (buildpack.Group, platform.BuildPlan, error) {
-	order, err := buildpack.ReadOrder(da.orderPath)
+	order, orderExt, err := buildpack.ReadOrder(da.orderPath)
 	if err != nil {
 		return buildpack.Group{}, platform.BuildPlan{}, cmd.FailErr(err, "read buildpack order file")
 	}
 	if err := da.verifyBuildableApis(order); err != nil {
 		return buildpack.Group{}, platform.BuildPlan{}, err
 	}
-
+	// TODO: this is pretty horrible, but it "works"
+	if len(orderExt) > 0 {
+		// update `Extension` for each group element, as this field is not defined in order.toml
+		for i, extGroup := range orderExt {
+			for j, el := range extGroup.Group {
+				el.Extension = true
+				extGroup.Group[j] = el
+			}
+			orderExt[i] = buildpack.Group{
+				Group: extGroup.Group,
+			}
+		}
+		// create group element to hold `order-ext`
+		extGroupElement := buildpack.GroupBuildable{
+			ID:       "some-order-ext-id",
+			Version:  "some-order-ext-version",
+			Optional: true, // TODO: should this always be true, for the whole order?
+			OrderExt: orderExt,
+		}
+		// add `orderExt` as a "metabuildpack" inside each group
+		for i, group := range order {
+			order[i] = buildpack.Group{
+				Group: append([]buildpack.GroupBuildable{extGroupElement}, group.Group...),
+			}
+		}
+		cmd.DefaultLogger.Infof("XXXXXXXXXX New order: %+v", order)
+	}
+	if err := da.verifyBuildableApis(orderExt); err != nil {
+		return buildpack.Group{}, platform.BuildPlan{}, err
+	}
 	detector, err := lifecycle.NewDetector(buildpack.DetectConfig{
 		AppDir:      da.appDir,
 		PlatformDir: da.platformDir,

detector.go

@@ -7,6 +7,7 @@ import (
 
 	"github.com/pkg/errors"
 
+	"github.com/buildpacks/lifecycle/api"
 	"github.com/buildpacks/lifecycle/buildpack"
 	"github.com/buildpacks/lifecycle/env"
 	"github.com/buildpacks/lifecycle/platform"
@@ -115,7 +116,11 @@ func (d *Detector) detectGroup(group buildpack.Group, done []buildpack.GroupBuil
 			buildable buildpack.Buildable
 			err       error
 		)
-		if groupBuildable.Extension {
+		if len(groupBuildable.OrderExt) > 0 {
+			// lookup won't return anything, because "order-ext" is defined in order.toml only (no buildpack.toml exists)
+			groupBuildable.API = api.Buildpack.Latest().String() // TODO: fix
+			return d.detectOrder(groupBuildable.OrderExt, done, group.Group[i+1:], groupBuildable.Optional, wg)
+		} else if groupBuildable.Extension {
 			if !groupBuildable.Optional {
 				// TODO: warn or error?
 				groupBuildable.Optional = true
@@ -366,7 +371,7 @@ type detectTrial []detectOption
 func (ts detectTrial) remove(bp buildpack.GroupBuildable) detectTrial {
 	var out detectTrial
 	for _, t := range ts {
-		if t.GroupBuildable != bp {
+		if t.GroupBuildable.ID != bp.ID || t.GroupBuildable.Version != bp.Version { // TODO: confirm if this works
 			out = append(out, t)
 		}
 	}

extender/testdata/layers/order.toml

@@ -1,18 +1,14 @@
-[[order]]
-[[order.group]]
+[[order-ext]]
+[[order-ext.group]]
 id = "samples/curl"
 version = "0.0.1"
-extension = true
-optional = true
 
-[[order.group]]
+[[order-ext.group]]
 id = "samples/rebasable"
 version = "0.0.1"
-extension = true
-optional = true
 
+[[order]]
 [[order.group]]
 id = "samples/use_curl"
 version = "0.0.1"
-extension = false
 optional = false

platform/order.go

@@ -0,0 +1 @@
+package platform