[Subtask]: Supports forwarding OpenAPI requests to the master node in master-slave mode.

amoro-ams/src/main/java/org/apache/amoro/server/AmoroManagementConf.java

@@ -368,6 +368,50 @@ public class AmoroManagementConf {
           .withDescription(
               "Interval for syncing tables assigned to bucket IDs in master-slave mode. Each node periodically loads tables from database based on its assigned bucket IDs.");
 
+  public static final ConfigOption<Duration> HA_REQUEST_FORWARDER_TIMEOUT =
+      ConfigOptions.key("ha.request-forwarder.timeout")
+          .durationType()
+          .defaultValue(Duration.ofSeconds(30))
+          .withDescription("Timeout duration for request forwarding to leader node.");
+
+  public static final ConfigOption<Integer> HA_REQUEST_FORWARDER_MAX_RETRIES =
+      ConfigOptions.key("ha.request-forwarder.max-retries")
+          .intType()
+          .defaultValue(3)
+          .withDescription("Maximum number of retry attempts for request forwarding.");
+
+  public static final ConfigOption<Duration> HA_REQUEST_FORWARDER_RETRY_BACKOFF =
+      ConfigOptions.key("ha.request-forwarder.retry-backoff")
+          .durationType()
+          .defaultValue(Duration.ofSeconds(1))
+          .withDescription("Backoff duration between retry attempts for request forwarding.");
+
+  public static final ConfigOption<Integer> HA_REQUEST_FORWARDER_CIRCUIT_BREAKER_THRESHOLD =
+      ConfigOptions.key("ha.request-forwarder.circuit-breaker.threshold")
+          .intType()
+          .defaultValue(5)
+          .withDescription("Number of consecutive failures before opening the circuit breaker.");
+
+  public static final ConfigOption<Duration> HA_REQUEST_FORWARDER_CIRCUIT_BREAKER_TIMEOUT =
+      ConfigOptions.key("ha.request-forwarder.circuit-breaker.timeout")
+          .durationType()
+          .defaultValue(Duration.ofMinutes(1))
+          .withDescription(
+              "Timeout duration for circuit breaker to remain open before attempting to close.");
+
+  public static final ConfigOption<Integer> HA_REQUEST_FORWARDER_MAX_CONNECTIONS =
+      ConfigOptions.key("ha.request-forwarder.max-connections")
+          .intType()
+          .defaultValue(100)
+          .withDescription("Maximum number of connections for request forwarding HTTP client.");
+
+  public static final ConfigOption<Integer> HA_REQUEST_FORWARDER_MAX_CONNECTIONS_PER_ROUTE =
+      ConfigOptions.key("ha.request-forwarder.max-connections-per-route")
+          .intType()
+          .defaultValue(20)
+          .withDescription(
+              "Maximum number of connections per route for request forwarding HTTP client.");
+
   public static final ConfigOption<Integer> TABLE_SERVICE_THRIFT_BIND_PORT =
       ConfigOptions.key("thrift-server.table-service.bind-port")
           .intType()

amoro-ams/src/main/java/org/apache/amoro/server/AmoroServiceContainer.java

@@ -33,13 +33,15 @@
 import org.apache.amoro.config.Configurations;
 import org.apache.amoro.config.shade.utils.ConfigShadeUtils;
 import org.apache.amoro.exception.AmoroRuntimeException;
+import org.apache.amoro.exception.RequestForwardedException;
 import org.apache.amoro.process.ActionCoordinator;
 import org.apache.amoro.process.ExecuteEngine;
 import org.apache.amoro.process.ProcessFactory;
 import org.apache.amoro.server.catalog.CatalogManager;
 import org.apache.amoro.server.catalog.DefaultCatalogManager;
 import org.apache.amoro.server.dashboard.DashboardServer;
 import org.apache.amoro.server.dashboard.JavalinJsonMapper;
+import org.apache.amoro.server.dashboard.RequestForwarder;
 import org.apache.amoro.server.dashboard.response.ErrorResponse;
 import org.apache.amoro.server.dashboard.utils.AmsUtil;
 import org.apache.amoro.server.dashboard.utils.CommonUtil;
@@ -128,6 +130,7 @@ public class AmoroServiceContainer {
   private AmsServiceMetrics amsServiceMetrics;
   private HAState haState = HAState.INITIALIZING;
   private AmsAssignService amsAssignService;
+  private RequestForwarder requestForwarder;
 
   public AmoroServiceContainer() throws Exception {
     initConfig();
@@ -360,6 +363,11 @@ public void disposeRestService() {
     if (amsServiceMetrics != null) {
       amsServiceMetrics.unregister();
     }
+    if (requestForwarder != null) {
+      LOG.info("Closing request forwarder...");
+      requestForwarder.close();
+      requestForwarder = null;
+    }
 
     EventsManager.dispose();
     MetricManager.dispose();
@@ -393,13 +401,69 @@ private void startThriftServer(TServer server, String threadName) {
   }
 
   private void initHttpService() {
+    // Create request forwarder for master-slave mode
+    requestForwarder = null;
+    if (haContainer != null && IS_MASTER_SLAVE_MODE) {
+      // Get configuration values for request forwarder
+      int timeoutMs =
+          (int) serviceConfig.get(AmoroManagementConf.HA_REQUEST_FORWARDER_TIMEOUT).toMillis();
+      int maxRetries =
+          serviceConfig.getInteger(AmoroManagementConf.HA_REQUEST_FORWARDER_MAX_RETRIES);
+      int retryBackoffMs =
+          (int)
+              serviceConfig.get(AmoroManagementConf.HA_REQUEST_FORWARDER_RETRY_BACKOFF).toMillis();
+      int circuitBreakerThreshold =
+          serviceConfig.getInteger(
+              AmoroManagementConf.HA_REQUEST_FORWARDER_CIRCUIT_BREAKER_THRESHOLD);
+      long circuitBreakerTimeoutMs =
+          serviceConfig
+              .get(AmoroManagementConf.HA_REQUEST_FORWARDER_CIRCUIT_BREAKER_TIMEOUT)
+              .toMillis();
+      int maxConnections =
+          serviceConfig.getInteger(AmoroManagementConf.HA_REQUEST_FORWARDER_MAX_CONNECTIONS);
+      int maxConnectionsPerRoute =
+          serviceConfig.getInteger(
+              AmoroManagementConf.HA_REQUEST_FORWARDER_MAX_CONNECTIONS_PER_ROUTE);
+
+      requestForwarder =
+          new org.apache.amoro.server.dashboard.RequestForwarder(
+              haContainer,
+              timeoutMs,
+              maxRetries,
+              retryBackoffMs,
+              circuitBreakerThreshold,
+              circuitBreakerTimeoutMs,
+              maxConnections,
+              maxConnectionsPerRoute,
+              IS_MASTER_SLAVE_MODE);
+
+      LOG.info(
+          "Request forwarder initialized with configuration: timeout={}ms, maxRetries={}, "
+              + "retryBackoff={}ms, circuitBreakerThreshold={}, circuitBreakerTimeout={}ms, "
+              + "maxConnections={}, maxConnectionsPerRoute={}",
+          timeoutMs,
+          maxRetries,
+          retryBackoffMs,
+          circuitBreakerThreshold,
+          circuitBreakerTimeoutMs,
+          maxConnections,
+          maxConnectionsPerRoute);
+    }
+
     DashboardServer dashboardServer =
         new DashboardServer(
-            serviceConfig, catalogManager, tableManager, optimizerManager, terminalManager, this);
+            serviceConfig,
+            catalogManager,
+            tableManager,
+            optimizerManager,
+            terminalManager,
+            this,
+            requestForwarder);
     RestExtensionManager restExtensionManager = new RestExtensionManager();
     restExtensionManager.initialize();
     List<RestExtension> restExtensions =
-        restExtensionManager.loadExtensions(serviceConfig, catalogManager, tableManager);
+        restExtensionManager.loadExtensions(
+            serviceConfig, catalogManager, tableManager, requestForwarder);
     Function<Context, Optional<RestExtension>> handleExceptionByExtension =
         ctx -> restExtensions.stream().filter(ext -> ext.needHandleException(ctx)).findFirst();
 
@@ -433,6 +497,79 @@ private void initHttpService() {
             dashboardServer.preHandleRequest(ctx);
           }
         });
+
+    // Handle RequestForwardedException - request was successfully forwarded to leader
+    // This must be registered before the generic Exception handler
+    httpServer.exception(
+        RequestForwardedException.class,
+        (e, ctx) -> {
+          // Request was forwarded, response data is stored in the exception
+          // Re-apply response data to ensure it's not lost during exception handling
+          if (e.hasResponseData()) {
+            // Set status code
+            ctx.status(e.getStatusCode());
+
+            // Set response body
+            byte[] responseBody = e.getResponseBody();
+            if (responseBody != null) {
+              // For 204/304, don't set body
+              if (e.getStatusCode() != 204 && e.getStatusCode() != 304) {
+                ctx.result(responseBody);
+              }
+            } else if (e.getStatusCode() != 204
+                && e.getStatusCode() != 304
+                && ctx.path().startsWith("/api/")) {
+              // Fallback: set empty JSON if body is null for API endpoints
+              ctx.result("{}".getBytes(java.nio.charset.StandardCharsets.UTF_8));
+            }
+
+            // Set content type
+            String contentType = e.getContentType();
+            if (contentType != null && !contentType.isEmpty()) {
+              ctx.contentType(contentType);
+            } else if (e.getStatusCode() != 204
+                && e.getStatusCode() != 304
+                && ctx.path().startsWith("/api/")) {
+              ctx.contentType("application/json");
+            }
+
+            // Set response headers
+            if (e.getResponseHeaders() != null) {
+              for (java.util.Map.Entry<String, String> entry : e.getResponseHeaders().entrySet()) {
+                ctx.header(entry.getKey(), entry.getValue());
+              }
+            }
+
+            LOG.debug(
+                "RequestForwardedException handled: restored response status {}, body-size: {}, content-type: {} for path: {}",
+                e.getStatusCode(),
+                responseBody != null ? responseBody.length : 0,
+                contentType,
+                ctx.path());
+          } else {
+            // Response data not available in exception, check if it was set in context
+            int currentStatus = ctx.status();
+            if (currentStatus > 0) {
+              LOG.debug(
+                  "RequestForwardedException caught: response already set in context, status: {} for path: {}",
+                  currentStatus,
+                  ctx.path());
+            } else {
+              LOG.error(
+                  "RequestForwardedException caught but no response data available! Path: {}",
+                  ctx.path());
+              // Set a proper error response
+              ctx.status(io.javalin.http.HttpCode.INTERNAL_SERVER_ERROR);
+              ctx.contentType("application/json");
+              ctx.json(
+                  new org.apache.amoro.server.dashboard.response.ErrorResponse(
+                      io.javalin.http.HttpCode.INTERNAL_SERVER_ERROR,
+                      "Request forwarding completed but response was not properly set",
+                      ""));
+            }
+          }
+        });
+
     httpServer.exception(
         Exception.class,
         (e, ctx) -> {
@@ -667,6 +804,11 @@ private void initContainerConfig() {
           containerProperties.putIfAbsent(
               OptimizerProperties.AMS_OPTIMIZER_URI,
               AmsUtil.getAMSThriftAddress(serviceConfig, Constants.THRIFT_OPTIMIZING_SERVICE_NAME));
+          // Add master-slave mode flag to container properties
+          if (serviceConfig.getBoolean(USE_MASTER_SLAVE_MODE)) {
+            containerProperties.put(
+                OptimizerProperties.OPTIMIZER_MASTER_SLAVE_MODE_ENABLED, "true");
+          }
           // put addition system properties
           container.setProperties(containerProperties);
           containerList.add(container);