Add support for project descriptor v0.2

Signed-off-by: Sambhav Kothari <skothari44@bloomberg.net>

pkg/cnb/project_descriptor.go

@@ -12,17 +12,12 @@ import (
 
 const defaultProjectDescriptorPath = "project.toml"
 
-func ProcessProjectDescriptor(appDir, descriptorPath, platformDir string, logger *log.Logger) error {
-	var (
-		d descriptor
-	)
-
-	file := filepath.Join(appDir, defaultProjectDescriptorPath)
+func ProcessProjectDescriptor(appDir,descriptorPath, platformDir string, logger *log.Logger) error {
+	filePath := filepath.Join(appDir, defaultProjectDescriptorPath)
 	if descriptorPath != "" {
-		file = filepath.Join(appDir, descriptorPath)
+		filePath = filepath.Join(appDir, descriptorPath)
 	}
-
-	if _, err := os.Stat(file); os.IsNotExist(err) {
+	if _, err := os.Stat(filePath); os.IsNotExist(err) {
 		if descriptorPath != "" {
 			return fmt.Errorf("project descriptor path set but no file found: %s", descriptorPath)
 		}
@@ -31,24 +26,50 @@ func ProcessProjectDescriptor(appDir, descriptorPath, platformDir string, logger
 		return fmt.Errorf("unable to determine if project descriptor file exists: %w", err)
 	}
 
-	_, err := toml.DecodeFile(file, &d)
+	d, err := parseProjectDescriptor(filePath, logger)
 	if err != nil {
 		return err
 	}
-	if d.Build.Buildpacks != nil {
+	if d.Buildpacks != nil {
 		logger.Println("info: buildpacks provided in project descriptor file will be ignored")
 	}
 
-	if d.Build.Builder != "" {
+	if d.Builder != "" {
 		logger.Println("info: builder provided in project descriptor file will be ignored")
 	}
 	if err := processFiles(appDir, d); err != nil {
 		return err
 	}
-	return serializeEnvVars(d.Build.Env, platformDir)
+	return serializeEnvVars(d.Env, platformDir)
 }
 
-func processFiles(appDir string, d descriptor) error {
+func parseProjectDescriptor(filePath string, logger *log.Logger) (build, error) {
+	var dv2 descriptorV2
+	if _, err := toml.DecodeFile(filePath, &dv2); err != nil {
+		return build{}, err
+	}
+
+	if dv2.Project.SchemaVersion != "" {
+		if dv2.Project.SchemaVersion == "0.2" {
+			// Normalizing the buildpacks table to a common schema
+			dv2.IO.Buildpacks.Buildpacks = dv2.IO.Buildpacks.Group
+			dv2.IO.Buildpacks.Group = nil
+			return dv2.IO.Buildpacks, nil
+		} else {
+			logger.Println(fmt.Sprintf("warning: project descriptor version %s is unsupported and %s will be ignored", dv2.Project.SchemaVersion, filePath))
+			return build{}, nil
+		}
+	}
+	var d descriptor
+	if _, err := toml.DecodeFile(filePath, &d); err != nil {
+		return build{}, err
+	}
+	// Removing groups from v1 descriptor if it exists
+	d.Build.Group = nil
+	return d.Build, nil
+}
+
+func processFiles(appDir string, d build) error {
 	fileFilter, err := getFileFilter(d)
 	if err != nil {
 		return err
@@ -77,19 +98,19 @@ func processFiles(appDir string, d descriptor) error {
 	})
 }
 
-func getFileFilter(d descriptor) (func(string) bool, error) {
-	if d.Build.Exclude != nil && d.Build.Include != nil {
-		return nil, fmt.Errorf("%s: cannot have both include and exclude defined", defaultProjectDescriptorPath)
+func getFileFilter(d build) (func(string) bool, error) {
+	if d.Exclude != nil && d.Include != nil {
+		return nil, fmt.Errorf("project descriptor cannot have both include and exclude defined")
 	}
 
-	if len(d.Build.Exclude) > 0 {
-		excludes := ignore.CompileIgnoreLines(d.Build.Exclude...)
+	if len(d.Exclude) > 0 {
+		excludes := ignore.CompileIgnoreLines(d.Exclude...)
 		return func(fileName string) bool {
 			return !excludes.MatchesPath(fileName)
 		}, nil
 	}
-	if len(d.Build.Include) > 0 {
-		includes := ignore.CompileIgnoreLines(d.Build.Include...)
+	if len(d.Include) > 0 {
+		includes := ignore.CompileIgnoreLines(d.Include...)
 		return includes.MatchesPath, nil
 	}
 
@@ -106,10 +127,24 @@ type build struct {
 	Include    []string      `toml:"include"`
 	Exclude    []string      `toml:"exclude"`
 	Buildpacks []buildpack   `toml:"buildpacks"`
+	Group      []buildpack   `toml:"group"`
 	Builder    string        `toml:"builder"`
 	Env        []envVariable `toml:"env"`
 }
 
 type descriptor struct {
 	Build build `toml:"build"`
 }
+
+type descriptorV2 struct {
+	Project project `toml:"_"`
+	IO      ioTable `toml:"io"`
+}
+
+type project struct {
+	SchemaVersion string `toml:"schema-version"`
+}
+
+type ioTable struct {
+	Buildpacks build `toml:"buildpacks"`
+}