feat: add LocationLevel as enum (#110)

api/v1/traffic_manage/routing.proto

@@ -153,14 +153,26 @@ message MetadataRoutingConfig {
 
 // NearbyRoutingConfig routing configuration
 message NearbyRoutingConfig {
+  enum LocationLevel {
+    // 未知就近级别，等同于未定义级别
+    UNKNOWN = 0;
+    // 机房就近级别
+    CAMPUS = 1;
+    // 可用区就近级别
+    ZONE = 2;
+    // 地域就近级别
+    REGION = 3;
+    // 全局就近级别
+    ALL = 4;
+  }
   // 被调服务名，支持*，代表全部服务
   string service = 1 [ json_name = "service" ];
   // 被调命名空间
   string namespace = 2 [ json_name = "namespace" ];
-  // 默认就近级别，为空时默认为zone
-  string match_level = 3 [ json_name = "match_level" ];
-  // 最大就近级别，为空值默认为none
-  string max_match_level = 4 [ json_name = "max_match_level" ];
+  // 默认就近级别
+  LocationLevel match_level = 3 [ json_name = "match_level" ];
+  // 最大就近级别
+  LocationLevel max_match_level = 4 [ json_name = "max_match_level" ];
   // 是否强制就近
   bool strict_nearby = 5 [ json_name = "strict_nearby" ];
 }