Flatten nested YAML data in specified config file

Signed-off-by: Ben Reedy <breed808@breed808.com>

config/config.go

@@ -43,12 +43,14 @@ func NewResolver(file string) (*Resolver, error) {
 		return nil, err
 	}
 
-	var m map[string]string
-	err = yaml.Unmarshal(b, &m)
+	var rawValues map[string]interface{}
+	err = yaml.Unmarshal(b, &rawValues)
 	if err != nil {
 		return nil, err
 	}
-	for k, v := range m {
+	// Flatten nested YAML values
+	flattenedValues := flatten(rawValues)
+	for k, v := range flattenedValues {
 		if _, ok := flags[k]; !ok {
 			flags[k] = v
 		}

config/flatten.go

@@ -0,0 +1,61 @@
+package config
+
+import "fmt"
+
+// flatten flattens the nested struct.
+//
+// All keys will be joined by dot
+// e.g. {"a": {"b":"c"}} => {"a.b":"c"}
+// or {"a": {"b":[1,2]}} => {"a.b.0":1, "a.b.1": 2}
+func flatten(data map[string]interface{}) map[string]string {
+	ret := make(map[string]string)
+	for k, v := range data {
+		switch typed := v.(type) {
+		case map[interface{}]interface{}:
+			for fk, fv := range flatten(convertMap(typed)) {
+				ret[fmt.Sprintf("%s.%s", k, fk)] = fv
+			}
+		case map[string]interface{}:
+			for fk, fv := range flatten(typed) {
+				ret[fmt.Sprintf("%s.%s", k, fk)] = fv
+			}
+		case []interface{}:
+			for fk, fv := range flattenSlice(typed) {
+				ret[fmt.Sprintf("%s.%s", k, fk)] = fv
+			}
+		default:
+			ret[k] = fmt.Sprint(typed)
+		}
+	}
+	return ret
+}
+func flattenSlice(data []interface{}) map[string]string {
+	ret := make(map[string]string)
+	for idx, v := range data {
+		switch typed := v.(type) {
+		case map[interface{}]interface{}:
+			for fk, fv := range flatten(convertMap(typed)) {
+				ret[fmt.Sprintf("%d,%s", idx, fk)] = fv
+			}
+		case map[string]interface{}:
+			for fk, fv := range flatten(typed) {
+				ret[fmt.Sprintf("%d,%s", idx, fk)] = fv
+			}
+		case []interface{}:
+			for fk, fv := range flattenSlice(typed) {
+				ret[fmt.Sprintf("%d,%s", idx, fk)] = fv
+			}
+		default:
+			ret[fmt.Sprint(idx)] = fmt.Sprint(typed)
+		}
+	}
+	return ret
+}
+
+func convertMap(originalMap map[interface{}]interface{}) map[string]interface{} {
+	convertedMap := map[string]interface{}{}
+	for key, value := range originalMap {
+		convertedMap[key.(string)] = value
+	}
+	return convertedMap
+}