feat:add tips when calling lossless deregister method. (#527)

Author: SkyeBeFreeman

polaris-plugins/polaris-plugin-api/src/main/java/com/tencent/polaris/api/plugin/lossless/LosslessPolicy.java

@@ -36,27 +36,34 @@ public interface LosslessPolicy extends Plugin, SortableAware {
 
     String OFFLINE_PATH = "/offline";
 
+    String REPS_TEXT_ONLY_LOCALHOST = "only localhost can call this path";
+
     String REPS_TEXT_NO_ACTION = "no action";
 
+    String REPS_TEXT_NO_POLICY = "no policy";
+
     String REPS_TEXT_OK = "ok";
 
     String REPS_TEXT_FAILED = "failed";
 
     /**
      * build or modify the instance properties
+     *
      * @param instanceProperties properties, for the callback register to set into instance
      */
     void buildInstanceProperties(InstanceProperties instanceProperties);
 
     /**
      * do lossless register
-     * @param instance instance to lossless register
+     *
+     * @param instance           instance to lossless register
      * @param instanceProperties properties, for the callback register to set into instance
      */
     void losslessRegister(BaseInstance instance, InstanceProperties instanceProperties);
 
     /**
      * do lossless deregister
+     *
      * @param instance instance to lossless deregister
      */
     void losslessDeregister(BaseInstance instance);

polaris-plugins/polaris-plugins-lossless/lossless-deregister/src/main/java/com/tencent/polaris/plugin/lossless/deregister/DeregisterLosslessPolicy.java

@@ -32,7 +32,6 @@
 import com.tencent.polaris.api.plugin.lossless.LosslessPolicy;
 import com.tencent.polaris.api.plugin.lossless.RegisterStatus;
 import com.tencent.polaris.api.pojo.BaseInstance;
-import com.tencent.polaris.api.rpc.BaseEntity;
 import com.tencent.polaris.api.utils.CollectionUtils;
 import com.tencent.polaris.client.pojo.Event;
 import com.tencent.polaris.client.util.HttpServerUtils;
@@ -93,8 +92,8 @@ public void handle(HttpExchange exchange) throws IOException {
             InetSocketAddress remoteAddress = exchange.getRemoteAddress();
             LOG.info("[LosslessDeregister] received lossless deregister request from {}", remoteAddress);
             if (!remoteAddress.getAddress().isLoopbackAddress()) {
-                exchange.sendResponseHeaders(403, 0);
-                exchange.close();
+                LOG.warn("[LosslessDeRegister] only loop-back address (like localhost or 127.0.0.1) can call this path");
+                HttpServerUtils.writeTextToHttpServer(exchange, REPS_TEXT_ONLY_LOCALHOST, 403);
                 return;
             }
             Map<BaseInstance, LosslessActionProvider> actionProviders = valueContext.getValue(LosslessActionProvider.CTX_KEY);
@@ -106,8 +105,8 @@ public void handle(HttpExchange exchange) throws IOException {
 
             List<LosslessPolicy> losslessPolicies = extensions.getLosslessPolicies();
             if (CollectionUtils.isEmpty(losslessPolicies)) {
-                LOG.warn("lossless is disabled, no losslessDeregister will do");
-                exchange.sendResponseHeaders(500, 0);
+                LOG.warn("[LosslessDeRegister] lossless is disabled, no losslessDeregister will do");
+                HttpServerUtils.writeTextToHttpServer(exchange, REPS_TEXT_NO_POLICY, 500);
                 exchange.close();
                 return;
             }