New static configuration loading system.

Co-authored-by: Mathieu Lonjaret <mathieu.lonjaret@gmail.com>

pkg/config/file/file_node.go

@@ -0,0 +1,86 @@
+package file
+
+import (
+	"fmt"
+	"io/ioutil"
+	"path/filepath"
+	"reflect"
+
+	"github.com/BurntSushi/toml"
+	"github.com/containous/traefik/pkg/config/parser"
+	"gopkg.in/yaml.v2"
+)
+
+// decodeFileToNode decodes the configuration in filePath in a tree of untyped nodes.
+// If filters is not empty, it skips any configuration element whose name is
+// not among filters.
+func decodeFileToNode(filePath string, filters ...string) (*parser.Node, error) {
+	content, err := ioutil.ReadFile(filePath)
+	if err != nil {
+		return nil, err
+	}
+
+	data := make(map[string]interface{})
+
+	switch filepath.Ext(filePath) {
+	case ".toml":
+		err = toml.Unmarshal(content, &data)
+		if err != nil {
+			return nil, err
+		}
+
+	case ".yml", ".yaml":
+		var err error
+		err = yaml.Unmarshal(content, data)
+		if err != nil {
+			return nil, err
+		}
+
+		return decodeRawToNode(data, filters...)
+
+	default:
+		return nil, fmt.Errorf("unsupported file extension: %s", filePath)
+	}
+
+	return decodeRawToNode(data, filters...)
+}
+
+func getRootFieldNames(element interface{}) []string {
+	if element == nil {
+		return nil
+	}
+
+	rootType := reflect.TypeOf(element)
+
+	return getFieldNames(rootType)
+}
+
+func getFieldNames(rootType reflect.Type) []string {
+	var names []string
+
+	if rootType.Kind() == reflect.Ptr {
+		rootType = rootType.Elem()
+	}
+
+	if rootType.Kind() != reflect.Struct {
+		return nil
+	}
+
+	for i := 0; i < rootType.NumField(); i++ {
+		field := rootType.Field(i)
+
+		if !parser.IsExported(field) {
+			continue
+		}
+
+		if field.Anonymous &&
+			(field.Type.Kind() == reflect.Ptr && field.Type.Elem().Kind() == reflect.Struct || field.Type.Kind() == reflect.Struct) {
+			names = append(names, getFieldNames(field.Type)...)
+			continue
+		}
+
+		names = append(names, field.Name)
+	}
+
+	return names
+}