improve file and redis loader

internal/loader/file.go

@@ -1,6 +1,7 @@
 package loader
 
 import (
+	"bufio"
 	"bytes"
 	"context"
 	"io"
@@ -26,6 +27,23 @@ func (l *fileLoader) Load(ctx context.Context) (io.Reader, error) {
 	return bytes.NewReader(data), nil
 }
 
+// List implements Lister interface{}
+func (l *fileLoader) List(ctx context.Context) (list []string, err error) {
+	f, err := os.Open(l.filename)
+	if err != nil {
+		return
+	}
+	defer f.Close()
+
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		list = append(list, scanner.Text())
+	}
+	err = scanner.Err()
+
+	return
+}
+
 func (l *fileLoader) Close() error {
 	return nil
 }