fixed serialization and middleware compose

internal/docker/label_parser.go

@@ -1,6 +1,7 @@
 package docker
 
 import (
+	"strconv"
 	"strings"
 
 	E "github.com/yusing/go-proxy/internal/error"
@@ -76,3 +77,11 @@ func BoolParser(value string) (any, E.NestedError) {
 		return nil, E.Invalid("boolean value", value)
 	}
 }
+
+func IntParser(value string) (any, E.NestedError) {
+	i, err := strconv.Atoi(value)
+	if err != nil {
+		return 0, E.Invalid("integer value", value)
+	}
+	return i, nil
+}