refactor(discovery): 优化实例注册逻辑处理

- 重构了元数据类型注册的处理流程，移除了空值检查的特殊处理逻辑
- 调整了IP类型和元数据类型的判断顺序，使代码逻辑更清晰
- 更新了Docker镜像版本号从v2.7.6到v2.7

Author: anjia0532

README.md

@@ -9,7 +9,7 @@ gateway等网关插件的高扩展性
 ### 通过docker运行
 
 ```bash
-docker run anjia0532/discovery-syncer-python:v2.7.6
+docker run anjia0532/discovery-syncer-python:v2.7.7
 ```
 
 特别的，`-c ` 支持配置远端http[s]的地址，比如读取静态资源的，比如读取nacos的

app/handler/discovery.py

@@ -43,16 +43,10 @@ def discovery(discovery_name: Annotated[str, Path(title="discovery_name", descri
         for instance in discovery_instances:
             val = ""
             change = instance.enabled
-            if registration.type == RegistrationType.METADATA:
-                val = instance.metadata.get(registration.metadata_key, "")
-                # 为了防止 metadata_key 为空，导致所有实例都下线，这里做个特殊处理
-                if len(val) == 0:
-                    if registration.other_status != RegistrationStatus.ORIGIN:
-                        instance.enabled = registration.other_status == RegistrationStatus.UP
-                        instance.change = change != instance.enabled
-                    continue
-            elif registration.type == RegistrationType.IP:
+            if registration.type == RegistrationType.IP:
                 val = instance.ip
+            elif registration.type == RegistrationType.METADATA:
+                val = instance.metadata.get(registration.metadata_key, "")
 
             if re.match(registration.regexp_str or '', val):
                 instance.enabled = registration.status == RegistrationStatus.UP