raise error in case of duplicate params in the configuration (#3593) (#3651)

internal/conf/conf_test.go

@@ -258,6 +258,12 @@ func TestConfErrors(t *testing.T) {
 		conf string
 		err  string
 	}{
+		{
+			"duplicate parameter",
+			"paths:\n" +
+				"paths:\n",
+			"yaml: unmarshal errors:\n  line 2: key \"paths\" already set in map",
+		},
 		{
 			"non existent parameter 1",
 			`invalid: param`,

internal/conf/yaml/load.go

@@ -44,8 +44,11 @@ func convertKeys(i interface{}) (interface{}, error) {
 // Load loads the configuration from Yaml.
 func Load(buf []byte, dest interface{}) error {
 	// load YAML into a generic map
+	// from documentation:
+	// "UnmarshalStrict is like Unmarshal except that any fields that are found in the data
+	// that do not have corresponding struct members, or mapping keys that are duplicates, will result in an error."
 	var temp interface{}
-	err := yaml.Unmarshal(buf, &temp)
+	err := yaml.UnmarshalStrict(buf, &temp)
 	if err != nil {
 		return err
 	}