fixup; legacy support

bindings/resolver.go

@@ -67,10 +67,18 @@ type Resolver struct {
 	bindings    []Binding
 }
 
-// NewResolver returns a new service binding resolver. If the SERVICE_BINDING_ROOT environment variable is not set, uses
-// the provided platform directory to resolve bindings at `<platformDir>/bindings`.
+// NewResolver returns a new service binding resolver. The location of the bindings is given by one of the following, in
+// the given order of precedence:
+//
+//  1. SERVICE_BINDING_ROOT environment variable
+//  2. CNB_BINDINGS environment variable, if above is not set
+//  3. `<platformDir>/bindings`, if both above are not set
 func NewResolver(platformDir string) *Resolver {
 	root := os.Getenv("SERVICE_BINDING_ROOT")
+	if root == "" {
+		root = os.Getenv("CNB_BINDINGS")
+	}
+
 	if root == "" {
 		root = filepath.Join(platformDir, "bindings")
 	}
@@ -123,7 +131,17 @@ func loadBindings(bindingRoot string) ([]Binding, error) {
 
 	var bindings []Binding
 	for _, file := range files {
-		binding, err := loadBinding(bindingRoot, file.Name())
+		isLegacy, err := isLegacyBinding(bindingRoot, file.Name())
+		if err != nil {
+			return nil, err
+		}
+
+		var binding Binding
+		if isLegacy {
+			binding, err = loadLegacyBinding(bindingRoot, file.Name())
+		} else {
+			binding, err = loadBinding(bindingRoot, file.Name())
+		}
 		if err != nil {
 			return nil, err
 		}
@@ -132,33 +150,111 @@ func loadBindings(bindingRoot string) ([]Binding, error) {
 	return bindings, nil
 }
 
-func loadBinding(bindingRoot, name string) (Binding, error) {
+// According to the legacy spec (https://github.com/buildpacks/spec/blob/main/extensions/bindings.md), a legacy binding
+// has a `metadata` directory within the binding path.
+func isLegacyBinding(bindingRoot string, name string) (bool, error) {
+	info, err := os.Stat(filepath.Join(bindingRoot, name, "metadata"))
+	if err == nil {
+		return info.IsDir(), nil
+	} else if os.IsNotExist(err) {
+		return false, nil
+	}
+	return false, err
+}
+
+func loadBinding(bindingRoot string, name string) (Binding, error) {
+	binding := Binding{
+		Name:   name,
+		Path:   filepath.Join(bindingRoot, name),
+		Secret: map[string]SecretReader{},
+	}
+
+	typeBytes, err := ioutil.ReadFile(filepath.Join(binding.Path, "type"))
+	if err != nil {
+		return Binding{}, err
+	}
+	binding.Type = string(typeBytes)
+
+	providerBytes, err := ioutil.ReadFile(filepath.Join(binding.Path, "provider"))
+	if err != nil && !os.IsNotExist(err) {
+		return Binding{}, err
+	}
+	if err == nil {
+		binding.Provider = string(providerBytes)
+	}
+
+	secrets, err := loadSecrets(filepath.Join(binding.Path), "type", "provider")
+	if err != nil {
+		return Binding{}, err
+	}
+	binding.Secret = secrets
+
+	return binding, nil
+}
+
+// See: https://github.com/buildpacks/spec/blob/main/extensions/bindings.md
+func loadLegacyBinding(bindingRoot string, name string) (Binding, error) {
 	binding := Binding{
 		Name:   name,
 		Path:   filepath.Join(bindingRoot, name),
 		Secret: map[string]SecretReader{},
 	}
 
-	files, err := ioutil.ReadDir(binding.Path)
+	typeBytes, err := ioutil.ReadFile(filepath.Join(binding.Path, "metadata", "kind"))
+	if err != nil {
+		return Binding{}, err
+	}
+	binding.Type = string(typeBytes)
+
+	providerBytes, err := ioutil.ReadFile(filepath.Join(binding.Path, "metadata", "provider"))
+	if err != nil {
+		return Binding{}, err
+	}
+	binding.Provider = string(providerBytes)
+
+	metadata, err := loadSecrets(filepath.Join(binding.Path, "metadata"), "kind", "provider")
+	if err != nil {
+		return Binding{}, err
+	}
+	binding.Secret = metadata
+
+	secrets, err := loadSecrets(filepath.Join(binding.Path, "secret"))
+	if err != nil {
+		return Binding{}, err
+	}
+	for k, v := range secrets {
+		binding.Secret[k] = v
+	}
+
+	return binding, nil
+}
+
+func loadSecrets(secretsPath string, exclude ...string) (map[string]SecretReader, error) {
+	secrets := map[string]SecretReader{}
+	files, err := ioutil.ReadDir(secretsPath)
 	if err != nil {
-		return Binding{}, nil
+		return nil, err
 	}
 
 	for _, file := range files {
-		content, err := os.ReadFile(filepath.Join(binding.Path, file.Name()))
-		if err != nil {
-			return Binding{}, err
+		if in(file.Name(), exclude) {
+			continue
 		}
 
-		switch file.Name() {
-		case "type":
-			binding.Type = string(content)
-		case "provider":
-			binding.Provider = string(content)
-		default:
-			binding.Secret[file.Name()] = MakeSecretReader(content)
+		content, err := os.ReadFile(filepath.Join(secretsPath, file.Name()))
+		if err != nil {
+			return nil, err
 		}
+		secrets[file.Name()] = MakeSecretReader(content)
 	}
+	return secrets, nil
+}
 
-	return binding, nil
+func in(item string, list []string) bool {
+	for _, s := range list {
+		if s == item {
+			return true
+		}
+	}
+	return false
 }