[ISSUE 9757][pulsar-admin] add cmd to get service url of the leader broker

pulsar-broker/src/main/java/org/apache/pulsar/broker/admin/impl/BrokersBase.java

@@ -43,6 +43,7 @@
 import javax.ws.rs.core.Response.Status;
 import org.apache.pulsar.broker.PulsarService.State;
 import org.apache.pulsar.broker.ServiceConfiguration;
+import org.apache.pulsar.broker.loadbalance.LeaderBroker;
 import org.apache.pulsar.broker.loadbalance.LoadManager;
 import org.apache.pulsar.broker.namespace.NamespaceService;
 import org.apache.pulsar.broker.service.BrokerService;
@@ -56,6 +57,7 @@
 import org.apache.pulsar.client.api.Reader;
 import org.apache.pulsar.client.api.Schema;
 import org.apache.pulsar.common.conf.InternalConfigurationData;
+import org.apache.pulsar.common.policies.data.BrokerInfo;
 import org.apache.pulsar.common.policies.data.NamespaceOwnershipStatus;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -92,6 +94,31 @@ public Set<String> getActiveBrokers(@PathParam("cluster") String cluster) throws
         }
     }
 
+    @GET
+    @Path("/leaderBroker")
+    @ApiOperation(
+            value = "Get the information of the leader broker.",
+            response = BrokerInfo.class)
+    @ApiResponses(
+            value = {
+                    @ApiResponse(code = 401, message = "Authentication required"),
+                    @ApiResponse(code = 403, message = "This operation requires super-user access"),
+                    @ApiResponse(code = 404, message = "Leader broker not found") })
+    public BrokerInfo getLeaderBroker() throws Exception {
+        validateSuperUserAccess();
+
+        try {
+            LeaderBroker leaderBroker = pulsar().getLeaderElectionService().getCurrentLeader()
+                    .orElseThrow(() -> new RestException(Status.NOT_FOUND, "Couldn't find leader broker"));
+            BrokerInfo brokerInfo = new BrokerInfo();
+            brokerInfo.setServiceUrl(leaderBroker.getServiceUrl());
+            return brokerInfo;
+        } catch (Exception e) {
+            LOG.error("[{}] Failed to get the information of the leader broker.", clientAppId(), e);
+            throw new RestException(e);
+        }
+    }
+
     @GET
     @Path("/{clusterName}/{broker-webserviceurl}/ownedNamespaces")
     @ApiOperation(value = "Get the list of namespaces served by the specific broker",

pulsar-broker/src/test/java/org/apache/pulsar/broker/admin/AdminApiTest.java

@@ -66,6 +66,7 @@
 import org.apache.pulsar.broker.PulsarService;
 import org.apache.pulsar.broker.ServiceConfiguration;
 import org.apache.pulsar.broker.auth.MockedPulsarServiceBaseTest;
+import org.apache.pulsar.broker.loadbalance.LeaderBroker;
 import org.apache.pulsar.broker.loadbalance.impl.SimpleLoadManagerImpl;
 import org.apache.pulsar.broker.namespace.NamespaceEphemeralData;
 import org.apache.pulsar.broker.namespace.NamespaceService;
@@ -109,6 +110,7 @@
 import org.apache.pulsar.common.policies.data.BacklogQuota.BacklogQuotaType;
 import org.apache.pulsar.common.policies.data.BacklogQuota.RetentionPolicy;
 import org.apache.pulsar.common.policies.data.BrokerAssignment;
+import org.apache.pulsar.common.policies.data.BrokerInfo;
 import org.apache.pulsar.common.policies.data.ClusterData;
 import org.apache.pulsar.common.policies.data.ConsumerStats;
 import org.apache.pulsar.common.policies.data.NamespaceIsolationData;
@@ -441,6 +443,9 @@ public void brokers() throws Exception {
         Assert.assertNotNull(list2);
         Assert.assertEquals(list2.size(), 1);
 
+        BrokerInfo leaderBroker = admin.brokers().getLeaderBroker();
+        Assert.assertEquals(leaderBroker.getServiceUrl(), pulsar.getLeaderElectionService().getCurrentLeader().map(LeaderBroker::getServiceUrl).get());
+
         Map<String, NamespaceOwnershipStatus> nsMap = admin.brokers().getOwnedNamespaces("test", list.get(0));
         // since sla-monitor ns is not created nsMap.size() == 1 (for HeartBeat Namespace)
         Assert.assertEquals(nsMap.size(), 1);
@@ -634,7 +639,7 @@ public void properties() throws PulsarAdminException {
         } catch (PulsarAdminException e) {
             assertTrue(e instanceof NotFoundException);
         }
-        
+
         Set<String> allowedClusters = Sets.newHashSet("test");
         TenantInfo tenantInfo = new TenantInfo(Sets.newHashSet("role1", "role2"), allowedClusters);
         admin.tenants().updateTenant("prop-xyz", tenantInfo);

pulsar-broker/src/test/java/org/apache/pulsar/broker/admin/AdminTest.java

@@ -70,6 +70,7 @@
 import org.apache.pulsar.broker.auth.MockedPulsarServiceBaseTest;
 import org.apache.pulsar.broker.authentication.AuthenticationDataHttps;
 import org.apache.pulsar.broker.cache.ConfigurationCacheService;
+import org.apache.pulsar.broker.loadbalance.LeaderBroker;
 import org.apache.pulsar.broker.web.PulsarWebResource;
 import org.apache.pulsar.broker.web.RestException;
 import org.apache.pulsar.common.conf.InternalConfigurationData;
@@ -79,6 +80,7 @@
 import org.apache.pulsar.common.policies.data.AutoFailoverPolicyData;
 import org.apache.pulsar.common.policies.data.AutoFailoverPolicyType;
 import org.apache.pulsar.common.policies.data.BundlesData;
+import org.apache.pulsar.common.policies.data.BrokerInfo;
 import org.apache.pulsar.common.policies.data.ClusterData;
 import org.apache.pulsar.common.policies.data.NamespaceIsolationData;
 import org.apache.pulsar.common.policies.data.Policies;
@@ -621,6 +623,9 @@ public void brokers() throws Exception {
         Set<String> activeBrokers = brokers.getActiveBrokers("use");
         assertEquals(activeBrokers.size(), 1);
         assertEquals(activeBrokers, Sets.newHashSet(pulsar.getAdvertisedAddress() + ":" + pulsar.getListenPortHTTP().get()));
+
+        BrokerInfo leaderBroker = brokers.getLeaderBroker();
+        assertEquals(leaderBroker.getServiceUrl(), pulsar.getLeaderElectionService().getCurrentLeader().map(LeaderBroker::getServiceUrl).get());
     }
 
     @Test

pulsar-client-admin-api/src/main/java/org/apache/pulsar/client/admin/Brokers.java

@@ -24,6 +24,7 @@
 import org.apache.pulsar.client.admin.PulsarAdminException.NotAuthorizedException;
 import org.apache.pulsar.client.admin.PulsarAdminException.NotFoundException;
 import org.apache.pulsar.common.conf.InternalConfigurationData;
+import org.apache.pulsar.common.policies.data.BrokerInfo;
 import org.apache.pulsar.common.policies.data.NamespaceOwnershipStatus;
 
 /**
@@ -72,6 +73,40 @@ public interface Brokers {
      */
     CompletableFuture<List<String>> getActiveBrokersAsync(String cluster);
 
+    /**
+     * Get the information of the leader broker.
+     * <p/>
+     * Get the information of the leader broker.
+     * <p/>
+     * Response Example:
+     *
+     * <pre>
+     * <code>{serviceUrl:"prod1-broker1.messaging.use.example.com:8080"}</code>
+     * </pre>
+     *
+     * @return the information of the leader broker.
+     * @throws PulsarAdminException
+     *             Unexpected error
+     */
+    BrokerInfo getLeaderBroker() throws PulsarAdminException;
+
+    /**
+     * Get the service url of the leader broker asynchronously.
+     * <p/>
+     * Get the service url of the leader broker.
+     * <p/>
+     * Response Example:
+     *
+     * <pre>
+     * <code>{serviceUrl:"prod1-broker1.messaging.use.example.com:8080"}</code>
+     * </pre>
+     *
+     * @return the service url of the leader broker
+     * @throws PulsarAdminException
+     *             Unexpected error
+     */
+    CompletableFuture<BrokerInfo> getLeaderBrokerAsync() throws PulsarAdminException;
+
     /**
      * Get the map of owned namespaces and their status from a single broker in the cluster.
      * <p/>

pulsar-client-admin/src/main/java/org/apache/pulsar/client/admin/internal/BrokersImpl.java

@@ -32,6 +32,7 @@
 import org.apache.pulsar.client.admin.PulsarAdminException;
 import org.apache.pulsar.client.api.Authentication;
 import org.apache.pulsar.common.conf.InternalConfigurationData;
+import org.apache.pulsar.common.policies.data.BrokerInfo;
 import org.apache.pulsar.common.policies.data.NamespaceOwnershipStatus;
 import org.apache.pulsar.common.util.Codec;
 
@@ -76,6 +77,39 @@ public void failed(Throwable throwable) {
         return future;
     }
 
+    @Override
+    public BrokerInfo getLeaderBroker() throws PulsarAdminException {
+        try {
+            return getLeaderBrokerAsync().get(this.readTimeoutMs, TimeUnit.MILLISECONDS);
+        } catch (ExecutionException e) {
+            throw (PulsarAdminException) e.getCause();
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+            throw new PulsarAdminException(e);
+        } catch (TimeoutException e) {
+            throw new PulsarAdminException.TimeoutException(e);
+        }
+    }
+
+    @Override
+    public CompletableFuture<BrokerInfo> getLeaderBrokerAsync() {
+        WebTarget path = adminBrokers.path("leaderBroker");
+        final CompletableFuture<BrokerInfo> future = new CompletableFuture<>();
+        asyncGetRequest(path,
+                new InvocationCallback<BrokerInfo>() {
+                    @Override
+                    public void completed(BrokerInfo leaderBroker) {
+                        future.complete(leaderBroker);
+                    }
+
+                    @Override
+                    public void failed(Throwable throwable) {
+                        future.completeExceptionally(getApiException(throwable.getCause()));
+                    }
+                });
+        return future;
+    }
+
     @Override
     public Map<String, NamespaceOwnershipStatus> getOwnedNamespaces(String cluster, String brokerUrl)
             throws PulsarAdminException {

pulsar-client-tools-test/src/test/java/org/apache/pulsar/admin/cli/PulsarAdminToolTest.java

@@ -75,6 +75,9 @@ public void brokers() throws Exception {
         brokers.run(split("list use"));
         verify(mockBrokers).getActiveBrokers("use");
 
+        brokers.run(split("leader-broker"));
+        verify(mockBrokers).getLeaderBroker();
+
         brokers.run(split("namespaces use --url http://my-service.url:8080"));
         verify(mockBrokers).getOwnedNamespaces("use", "http://my-service.url:8080");
 

pulsar-client-tools/src/main/java/org/apache/pulsar/admin/cli/CmdBrokers.java

@@ -40,6 +40,15 @@ void run() throws Exception {
         }
     }
 
+    @Parameters(commandDescription = "Get the information of the leader broker")
+    private class LeaderBroker extends CliCommand {
+
+        @Override
+        void run() throws Exception {
+            print(getAdmin().brokers().getLeaderBroker());
+        }
+    }
+
     @Parameters(commandDescription = "List namespaces owned by the broker")
     private class Namespaces extends CliCommand {
         @Parameter(description = "cluster-name\n", required = true)
@@ -77,7 +86,7 @@ void run() throws Exception {
             getAdmin().brokers().deleteDynamicConfiguration(configName);
         }
     }
-    
+
     @Parameters(commandDescription = "Get all overridden dynamic-configuration values")
     private class GetAllConfigurationsCmd extends CliCommand {
 
@@ -86,7 +95,7 @@ void run() throws Exception {
             print(getAdmin().brokers().getAllDynamicConfigurations());
         }
     }
-    
+
     @Parameters(commandDescription = "Get list of updatable configuration name")
     private class GetUpdatableConfigCmd extends CliCommand {
 
@@ -140,6 +149,7 @@ void run() throws Exception {
     public CmdBrokers(Supplier<PulsarAdmin> admin) {
         super("brokers", admin);
         jcommander.addCommand("list", new List());
+        jcommander.addCommand("leader-broker", new LeaderBroker());
         jcommander.addCommand("namespaces", new Namespaces());
         jcommander.addCommand("update-dynamic-config", new UpdateConfigurationCmd());
         jcommander.addCommand("delete-dynamic-config", new DeleteConfigurationCmd());

pulsar-common/src/main/java/org/apache/pulsar/common/policies/data/BrokerInfo.java

@@ -0,0 +1,33 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.pulsar.common.policies.data;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+/**
+ * Broker Information
+ */
+@Data
+@AllArgsConstructor
+@NoArgsConstructor
+public class BrokerInfo {
+    private String serviceUrl;
+}

site2/docs/admin-api-brokers.md

@@ -48,6 +48,34 @@ admin.brokers().getActiveBrokers(clusterName)
 
 <!--END_DOCUSAURUS_CODE_TABS-->
 
+### Get the information of the leader broker
+
+Fetch the information of the leader broker, for example, the service url.
+
+<!--DOCUSAURUS_CODE_TABS-->
+<!--pulsar-admin-->
+
+```shell
+$ pulsar-admin brokers leader-broker
+```
+
+```
+BrokerInfo(serviceUrl=broker1.use.org.com:8080)
+```
+
+<!--REST API-->
+
+{@inject: endpoint|GET|/admin/v2/brokers/leaderBroker?version=[[pulsar:version_number]]}
+
+<!--JAVA-->
+
+```java
+admin.brokers().getLeaderBroker()
+```
+For the detail of the code above, see [here](https://github.com/apache/pulsar/blob/master/pulsar-client-admin/src/main/java/org/apache/pulsar/client/admin/internal/BrokersImpl.java#L80)
+
+<!--END_DOCUSAURUS_CODE_TABS-->
+
 #### list of namespaces owned by a given broker
 
 It finds all namespaces which are owned and served by a given broker.

site2/docs/reference-pulsar-admin.md

@@ -135,6 +135,14 @@ Usage
 $ pulsar-admin brokers list cluster-name
 ```
 
+### `leader-broker`
+Get the information of the leader broker
+
+Usage
+```bash
+$ pulsar-admin brokers leader-broker
+```
+
 ### `namespaces`
 List namespaces owned by the broker