[PLAT-14787] Implement a master tablet lb api for YW

Summary:
An API that returns if the master tablet load balancer is disabled, enabled & idle or enabled & running. If running, an estimate of the time to go back to idle is provided if it is possible to get such an estimate.

```
$ '/usr/bin/curl' '-s' '--insecure' '-H' 'X-AUTH-TOKEN: xxxxx' '-X' 'GET' 'http://localhost:9000/api/v1/customers/f33e3c9b-75ab-4c30-80ad-cba85646ea39/universes/180f069f-adf3-49b9-86ab-7a4fb4bc5d3e/master_lb_state'

{"isEnabled":false}
{"isEnabled":true, "isIdle": true}
{"isEnabled":true, "isIdle": false, "estTimeToBalanceSecs":987}

```

Also added the relevant metrics used here on the metrics page.

Test Plan:
1. Turn off the master lb with `tserver/bin/yb-admin --init_master_addrs=10.9.207.233 set_load_balancer_enabled 0`, verify the response is
```
{"isEnabled":false}
```

2. Turn back the master lb on with `tserver/bin/yb-admin --init_master_addrs=10.9.207.233 set_load_balancer_enabled 1`, verify the response is
```
{"isEnabled":true,"isIdle":true}
```

3. Verify lb progress is reflected correctly. Create some tables with lot of tablets

```
seq 1 10 | while read i; do
tserver/bin/ysqlsh -h /tmp/.yb.10.9.207.233\:5433/ -c "create table foo$i(id int) split into 150 tablets; insert into foo$i (select * from generate_series(1,1000));";
done
```

and slow down the master LB by setting master gflag `load_balancer_max_concurrent_moves to 1`. Then trigger the master lb by leader blacklisting one of the tservers `tserver/bin/yb-admin --init_master_addrs=10.9.207.233 change_leader_blacklist ADD 10.9.142.7`. Verify that the master LB is now running via
```
 tserver/bin/yb-admin --init_master_addrs=10.9.207.233 get_is_load_balancer_idle
Idle = 0
```
and that the API response matches this
```
{"isEnabled":true,"isIdle":false}
```
After all the moves are complete, verify that the response returns to
```
{"isEnabled":true,"isIdle":true}
```

Reviewers: cwang, yshchetinin

Reviewed By: cwang, yshchetinin

Subscribers: yugaware

Differential Revision: https://phorge.dev.yugabyte.com/D36164

java/interface-annotations/pom.xml

@@ -21,7 +21,7 @@
   <parent>
     <groupId>org.yb</groupId>
     <artifactId>yb-parent</artifactId>
-    <version>0.8.92-SNAPSHOT</version>
+    <version>0.8.93-SNAPSHOT</version>
   </parent>
 
   <artifactId>interface-annotations</artifactId>

java/pom.xml

@@ -40,7 +40,7 @@
 
   <groupId>org.yb</groupId>
   <artifactId>yb-parent</artifactId>
-  <version>0.8.92-SNAPSHOT</version>
+  <version>0.8.93-SNAPSHOT</version>
   <packaging>pom</packaging>
 
   <name>Yugabyte</name>

java/yb-cdc/pom.xml

@@ -5,7 +5,7 @@
   <parent>
     <groupId>org.yb</groupId>
     <artifactId>yb-parent</artifactId>
-    <version>0.8.92-SNAPSHOT</version>
+    <version>0.8.93-SNAPSHOT</version>
   </parent>
   <artifactId>yb-cdc</artifactId>
   <name>YB CDC Connector</name>

java/yb-cli/pom.xml

@@ -25,7 +25,7 @@
   <parent>
     <groupId>org.yb</groupId>
     <artifactId>yb-parent</artifactId>
-    <version>0.8.92-SNAPSHOT</version>
+    <version>0.8.93-SNAPSHOT</version>
   </parent>
 
   <artifactId>yb-cli</artifactId>

java/yb-client/pom.xml

@@ -25,7 +25,7 @@
   <parent>
     <groupId>org.yb</groupId>
     <artifactId>yb-parent</artifactId>
-    <version>0.8.92-SNAPSHOT</version>
+    <version>0.8.93-SNAPSHOT</version>
   </parent>
 
   <artifactId>yb-client</artifactId>

java/yb-client/src/main/java/org/yb/client/AsyncYBClient.java

@@ -1059,6 +1059,19 @@ public Deferred<ChangeLoadBalancerStateResponse> changeLoadBalancerState(boolean
     return sendRpcToTablet(rpc);
   }
 
+  /**
+   * Get the load balancer state on master.
+   *
+   * @return a deferred object that yields the response to the config change.
+   */
+  public Deferred<GetLoadBalancerStateResponse> getLoadBalancerState() {
+    checkIsClosed();
+    GetLoadBalancerStateRequest rpc =
+        new GetLoadBalancerStateRequest(this.masterTable);
+    rpc.setTimeoutMillis(defaultAdminOperationTimeoutMs);
+    return sendRpcToTablet(rpc);
+  }
+
   /**
    * Get the tablet load move completion percentage for blacklisted nodes.
    *

java/yb-client/src/main/java/org/yb/client/GetLoadBalancerStateRequest.java

@@ -0,0 +1,67 @@
+// Copyright (c) YugaByte, Inc.
+//
+// Licensed 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.yb.client;
+
+import com.google.protobuf.Message;
+import io.netty.buffer.ByteBuf;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.yb.annotations.InterfaceAudience;
+import org.yb.master.MasterClusterOuterClass;
+import org.yb.master.MasterClusterOuterClass.GetLoadBalancerStateRequestPB;
+import org.yb.util.Pair;
+
+@InterfaceAudience.Public
+public class GetLoadBalancerStateRequest extends YRpc<GetLoadBalancerStateResponse> {
+
+  public static final Logger LOG = LoggerFactory.getLogger(GetLoadBalancerStateRequest.class);
+
+  public GetLoadBalancerStateRequest(YBTable table) {
+    // The passed table will be a master table from AsyncYBClient since this service is registered
+    // on master.
+    super(table);
+  }
+
+  @Override
+  ByteBuf serialize(Message header) {
+    assert header.isInitialized();
+    final GetLoadBalancerStateRequestPB.Builder builder =
+        GetLoadBalancerStateRequestPB.newBuilder();
+    return toChannelBuffer(header, builder.build());
+  }
+
+  @Override
+  String serviceName() {
+    return MASTER_SERVICE_NAME;
+  }
+
+  @Override
+  String method() {
+    return "GetLoadBalancerState";
+  }
+
+  @Override
+  Pair<GetLoadBalancerStateResponse, Object> deserialize(CallResponse callResponse, String uuid)
+      throws Exception {
+    final MasterClusterOuterClass.GetLoadBalancerStateResponsePB.Builder respBuilder =
+        MasterClusterOuterClass.GetLoadBalancerStateResponsePB.newBuilder();
+    readProtobuf(callResponse.getPBMessage(), respBuilder);
+
+    GetLoadBalancerStateResponse response =
+        new GetLoadBalancerStateResponse(
+            deadlineTracker.getElapsedMillis(), uuid, respBuilder.build());
+    return new Pair<GetLoadBalancerStateResponse, Object>(
+        response, respBuilder.hasError() ? respBuilder.getError() : null);
+  }
+}

java/yb-client/src/main/java/org/yb/client/GetLoadBalancerStateResponse.java

@@ -0,0 +1,54 @@
+// Copyright (c) YugaByte, Inc.
+//
+// Licensed 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.yb.client;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.yb.annotations.InterfaceAudience;
+import org.yb.master.MasterClusterOuterClass.GetLoadBalancerStateResponsePB;
+import org.yb.master.MasterTypes.MasterErrorPB;
+
+@InterfaceAudience.Public
+public class GetLoadBalancerStateResponse extends YRpcResponse {
+
+  public static final Logger LOG = LoggerFactory.getLogger(GetLoadBalancerStateResponse.class);
+
+  private GetLoadBalancerStateResponsePB masterLBState;
+
+  public GetLoadBalancerStateResponse(
+      long elapsedMillis, String uuid, GetLoadBalancerStateResponsePB response) {
+    super(elapsedMillis, uuid);
+    this.masterLBState = response;
+  }
+
+  public MasterErrorPB getServerError() {
+    return masterLBState.getError();
+  }
+
+  public boolean hasError() {
+    return masterLBState.hasError();
+  }
+
+  public String errorMessage() {
+    return masterLBState.hasError() ? masterLBState.getError().getStatus().getMessage() : null;
+  }
+
+  public boolean hasIsEnabled() {
+    return masterLBState.hasIsEnabled();
+  }
+
+  public boolean isEnabled() {
+    return masterLBState.getIsEnabled();
+  }
+}

java/yb-client/src/main/java/org/yb/client/IsLoadBalancedRequest.java

@@ -34,7 +34,9 @@ ByteBuf serialize(Message header) {
     assert header.isInitialized();
     final MasterClusterOuterClass.IsLoadBalancedRequestPB.Builder builder =
       MasterClusterOuterClass.IsLoadBalancedRequestPB.newBuilder();
-    builder.setExpectedNumServers(expectedServers);
+    if (expectedServers != 0) {
+      builder.setExpectedNumServers(expectedServers);
+    }
     return toChannelBuffer(header, builder.build());
   }
 

java/yb-client/src/main/java/org/yb/client/IsLoadBalancerIdleResponse.java

@@ -27,6 +27,10 @@ public IsLoadBalancerIdleResponse(long ellapsedMillis,
     serverError = error;
   }
 
+  public MasterTypes.MasterErrorPB getError() {
+    return serverError;
+  }
+
   public boolean hasError() {
     return serverError != null;
   }

java/yb-client/src/main/java/org/yb/client/YBClient.java

@@ -458,6 +458,17 @@ public ChangeLoadBalancerStateResponse changeLoadBalancerState(boolean isEnable)
     return d.join(getDefaultAdminOperationTimeoutMs());
   }
 
+  /**
+   * Get the load balancer state.
+   *
+   * @return the response of the operation.
+   */
+  public GetLoadBalancerStateResponse getLoadBalancerState()
+      throws Exception {
+    Deferred<GetLoadBalancerStateResponse> d = asyncClient.getLoadBalancerState();
+    return d.join(getDefaultAdminOperationTimeoutMs());
+  }
+
   /**
    * Get the tablet load move completion percentage for blacklisted nodes, if any.
    *

java/yb-cql-4x/pom.xml

@@ -7,7 +7,7 @@
   <parent>
     <groupId>org.yb</groupId>
     <artifactId>yb-parent</artifactId>
-    <version>0.8.92-SNAPSHOT</version>
+    <version>0.8.93-SNAPSHOT</version>
   </parent>
   <artifactId>yb-cql-4x</artifactId>
   <name>YB CQL Support for 4.x Driver</name>

java/yb-cql/pom.xml

@@ -7,7 +7,7 @@
   <parent>
     <groupId>org.yb</groupId>
     <artifactId>yb-parent</artifactId>
-    <version>0.8.92-SNAPSHOT</version>
+    <version>0.8.93-SNAPSHOT</version>
   </parent>
   <artifactId>yb-cql</artifactId>
   <name>YB CQL Support</name>

java/yb-jedis-tests/pom.xml

@@ -7,7 +7,7 @@
   <parent>
     <groupId>org.yb</groupId>
     <artifactId>yb-parent</artifactId>
-    <version>0.8.92-SNAPSHOT</version>
+    <version>0.8.93-SNAPSHOT</version>
   </parent>
   <artifactId>yb-jedis-tests</artifactId>
   <name>YB Jedis Tests</name>

java/yb-loadtester/pom.xml

@@ -6,7 +6,7 @@
   <parent>
     <groupId>org.yb</groupId>
     <artifactId>yb-parent</artifactId>
-    <version>0.8.92-SNAPSHOT</version>
+    <version>0.8.93-SNAPSHOT</version>
   </parent>
 
   <artifactId>yb-loadtester</artifactId>

java/yb-multiapi/pom.xml

@@ -9,7 +9,7 @@
   <parent>
     <groupId>org.yb</groupId>
     <artifactId>yb-parent</artifactId>
-    <version>0.8.92-SNAPSHOT</version>
+    <version>0.8.93-SNAPSHOT</version>
   </parent>
 
   <artifactId>yb-multiapi</artifactId>

java/yb-pgsql/pom.xml

@@ -8,7 +8,7 @@
   <parent>
     <groupId>org.yb</groupId>
     <artifactId>yb-parent</artifactId>
-    <version>0.8.92-SNAPSHOT</version>
+    <version>0.8.93-SNAPSHOT</version>
   </parent>
   <artifactId>yb-pgsql</artifactId>
   <name>YB PostgreSQL Support</name>

java/yb-sample/pom.xml

@@ -8,7 +8,7 @@
   <parent>
     <groupId>org.yb</groupId>
     <artifactId>yb-parent</artifactId>
-    <version>0.8.92-SNAPSHOT</version>
+    <version>0.8.93-SNAPSHOT</version>
   </parent>
   <artifactId>yb-sample</artifactId>
   <name>YB Manual Support</name>

java/yb-ysql-conn-mgr/pom.xml

@@ -22,7 +22,7 @@
   <parent>
     <groupId>org.yb</groupId>
     <artifactId>yb-parent</artifactId>
-    <version>0.8.92-SNAPSHOT</version>
+    <version>0.8.93-SNAPSHOT</version>
   </parent>
   <artifactId>yb-ysql-conn-mgr</artifactId>
   <name>Ysql Connection Manager Tests</name>

java/yb-yugabyted/pom.xml

@@ -10,7 +10,7 @@
   <parent>
     <groupId>org.yb</groupId>
     <artifactId>yb-parent</artifactId>
-    <version>0.8.92-SNAPSHOT</version>
+    <version>0.8.93-SNAPSHOT</version>
     </parent>
   <artifactId>yb-yugabyted</artifactId>
 

managed/build.sbt

@@ -926,7 +926,7 @@ runPlatform := {
   Project.extract(newState).runTask(runPlatformTask, newState)
 }
 
-libraryDependencies += "org.yb" % "yb-client" % "0.8.92-SNAPSHOT"
+libraryDependencies += "org.yb" % "yb-client" % "0.8.93-SNAPSHOT"
 libraryDependencies += "org.yb" % "ybc-client" % "2.2.0.0-b3"
 libraryDependencies += "org.yb" % "yb-perf-advisor" % "1.0.0-b33"
 

managed/src/main/java/com/yugabyte/yw/controllers/MetaMasterController.java

@@ -9,6 +9,8 @@
 import com.yugabyte.yw.common.rbac.PermissionInfo.Action;
 import com.yugabyte.yw.common.rbac.PermissionInfo.ResourceType;
 import com.yugabyte.yw.common.services.YBClientService;
+import com.yugabyte.yw.controllers.apiModels.MasterLBStateResponse;
+import com.yugabyte.yw.controllers.handlers.MetaMasterHandler;
 import com.yugabyte.yw.forms.PlatformResults;
 import com.yugabyte.yw.models.Customer;
 import com.yugabyte.yw.models.Universe;
@@ -42,6 +44,8 @@ public class MetaMasterController extends Controller {
 
   @Inject KubernetesManagerFactory kubernetesManagerFactory;
 
+  @Inject MetaMasterHandler metaMasterHandler;
+
   @ApiOperation(
       value = "List a universe's master nodes",
       response = MastersList.class,
@@ -78,6 +82,22 @@ public Result getMasterAddresses(UUID customerUUID, UUID universeUUID) {
     return getServerAddresses(customerUUID, universeUUID, ServerType.MASTER);
   }
 
+  @ApiOperation(
+      notes = "Available since YBA version 2024.2.0",
+      value = "Get the state of master load balancing ops",
+      response = MasterLBStateResponse.class)
+  @YbaApi(visibility = YbaApi.YbaApiVisibility.INTERNAL, sinceYBAVersion = "2024.2.0")
+  @AuthzPath({
+    @RequiredPermissionOnResource(
+        requiredPermission =
+            @PermissionAttribute(resourceType = ResourceType.UNIVERSE, action = Action.READ),
+        resourceLocation = @Resource(path = Util.UNIVERSES, sourceType = SourceType.ENDPOINT))
+  })
+  public Result getMasterLBState(UUID customerUUID, UUID universeUUID) {
+    MasterLBStateResponse resp = metaMasterHandler.getMasterLBState(customerUUID, universeUUID);
+    return PlatformResults.withData(resp);
+  }
+
   @ApiOperation(
       notes = "Available since YBA version 2.2.0.0.",
       value = "List a YQL server's addresses",

managed/src/main/java/com/yugabyte/yw/controllers/apiModels/MasterLBStateResponse.java

@@ -0,0 +1,32 @@
+/*
+ * Copyright 2024 YugaByte, Inc. and Contributors
+ *
+ * Licensed under the Polyform Free Trial License 1.0.0 (the "License"); you
+ * may not use this file except in compliance with the License. You
+ * may obtain a copy of the License at
+ *
+ * http://github.com/YugaByte/yugabyte-db/blob/master/licenses/POLYFORM-FREE-TRIAL-LICENSE-1.0.0.txt
+ */
+package com.yugabyte.yw.controllers.apiModels;
+
+import io.swagger.annotations.ApiModel;
+import io.swagger.annotations.ApiModelProperty;
+
+@ApiModel(description = "Master tablet load balancer status")
+public class MasterLBStateResponse {
+  @ApiModelProperty(
+      required = true,
+      value = "YbaApi Internal Whether master tablet load balancer is enabled")
+  public Boolean isEnabled;
+
+  @ApiModelProperty(
+      required = false,
+      value = "YbaApi Internal Whether master tablet load balancer is inactive")
+  public Boolean isIdle;
+
+  @ApiModelProperty(
+      required = false,
+      value =
+          "YbaApi Internal Estimate of time for which master tablet load balancer will be active")
+  public Long estTimeToBalanceSecs;
+}