YARN-10022. Add RM Rest API to validate a CapacityScheduler Config with delta change

Contributed by Kinga Marton.

(cherry-picked from commit 1ab9c692fa)

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/MutableConfigurationProvider.java

@@ -51,6 +51,16 @@ public interface MutableConfigurationProvider {
   void logAndApplyMutation(UserGroupInformation user, SchedConfUpdateInfo
       confUpdate) throws Exception;
 
+  /**
+   * Apply the changes on top of the actual configuration.
+   * @param oldConfiguration actual configuration
+   * @param confUpdate changelist
+   * @return new configuration with the applied changed
+   * @throws IOException if the merge failed
+   */
+  Configuration applyChanges(Configuration oldConfiguration,
+                             SchedConfUpdateInfo confUpdate) throws IOException;
+
   /**
    * Confirm last logged mutation.
    * @param isValid if the last logged mutation is applied to scheduler

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/CapacityScheduler.java

@@ -209,40 +209,9 @@ public class CapacityScheduler extends
 
   private void validateConf(Configuration conf) {
     // validate scheduler memory allocation setting
-    int minMem = conf.getInt(
-      YarnConfiguration.RM_SCHEDULER_MINIMUM_ALLOCATION_MB,
-      YarnConfiguration.DEFAULT_RM_SCHEDULER_MINIMUM_ALLOCATION_MB);
-    int maxMem = conf.getInt(
-      YarnConfiguration.RM_SCHEDULER_MAXIMUM_ALLOCATION_MB,
-      YarnConfiguration.DEFAULT_RM_SCHEDULER_MAXIMUM_ALLOCATION_MB);
-
-    if (minMem <= 0 || minMem > maxMem) {
-      throw new YarnRuntimeException("Invalid resource scheduler memory"
-        + " allocation configuration"
-        + ", " + YarnConfiguration.RM_SCHEDULER_MINIMUM_ALLOCATION_MB
-        + "=" + minMem
-        + ", " + YarnConfiguration.RM_SCHEDULER_MAXIMUM_ALLOCATION_MB
-        + "=" + maxMem + ", min and max should be greater than 0"
-        + ", max should be no smaller than min.");
-    }
-
+    CapacitySchedulerConfigValidator.validateMemoryAllocation(conf);
     // validate scheduler vcores allocation setting
-    int minVcores = conf.getInt(
-      YarnConfiguration.RM_SCHEDULER_MINIMUM_ALLOCATION_VCORES,
-      YarnConfiguration.DEFAULT_RM_SCHEDULER_MINIMUM_ALLOCATION_VCORES);
-    int maxVcores = conf.getInt(
-      YarnConfiguration.RM_SCHEDULER_MAXIMUM_ALLOCATION_VCORES,
-      YarnConfiguration.DEFAULT_RM_SCHEDULER_MAXIMUM_ALLOCATION_VCORES);
-
-    if (minVcores <= 0 || minVcores > maxVcores) {
-      throw new YarnRuntimeException("Invalid resource scheduler vcores"
-        + " allocation configuration"
-        + ", " + YarnConfiguration.RM_SCHEDULER_MINIMUM_ALLOCATION_VCORES
-        + "=" + minVcores
-        + ", " + YarnConfiguration.RM_SCHEDULER_MAXIMUM_ALLOCATION_VCORES
-        + "=" + maxVcores + ", min and max should be greater than 0"
-        + ", max should be no smaller than min.");
-    }
+    CapacitySchedulerConfigValidator.validateVCores(conf);
   }
 
   @Override
@@ -482,14 +451,18 @@ public class CapacityScheduler extends
     super.serviceStop();
   }
 
-  @Override
-  public void reinitialize(Configuration newConf, RMContext rmContext)
-      throws IOException {
+  public void reinitialize(Configuration newConf, RMContext rmContext,
+         boolean validation) throws IOException {
+    writeLock.lock();
     try {
       writeLock.lock();
       Configuration configuration = new Configuration(newConf);
       CapacitySchedulerConfiguration oldConf = this.conf;
-      this.conf = csConfProvider.loadConfiguration(configuration);
+      if (validation) {
+        this.conf = new CapacitySchedulerConfiguration(newConf, false);
+      } else {
+        this.conf = csConfProvider.loadConfiguration(configuration);
+      }
       validateConf(this.conf);
       try {
         LOG.info("Re-initializing queues...");
@@ -503,17 +476,26 @@ public class CapacityScheduler extends
         throw new IOException("Failed to re-init queues : " + t.getMessage(),
             t);
       }
+      if (!validation) {
 
-      // update lazy preemption
-      this.isLazyPreemptionEnabled = this.conf.getLazyPreemptionEnabled();
+        // update lazy preemption
+        this.isLazyPreemptionEnabled = this.conf.getLazyPreemptionEnabled();
 
-      // Setup how many containers we can allocate for each round
-      offswitchPerHeartbeatLimit = this.conf.getOffSwitchPerHeartbeatLimit();
+        // Setup how many containers we can allocate for each round
+        offswitchPerHeartbeatLimit = this.conf.getOffSwitchPerHeartbeatLimit();
 
-      super.reinitialize(newConf, rmContext);
+        super.reinitialize(newConf, rmContext);
+      }
     } finally {
       writeLock.unlock();
     }
+
+  }
+
+  @Override
+  public void reinitialize(Configuration newConf, RMContext rmContext)
+      throws IOException {
+    reinitialize(newConf, rmContext, false);
   }
 
   long getAsyncScheduleInterval() {
@@ -717,19 +699,13 @@ public class CapacityScheduler extends
     Collection<String> placementRuleStrs = conf.getStringCollection(
         YarnConfiguration.QUEUE_PLACEMENT_RULES);
     List<PlacementRule> placementRules = new ArrayList<>();
-    Set<String> distingushRuleSet = new HashSet<>();
-    // fail the case if we get duplicate placementRule add in
-    for (String pls : placementRuleStrs) {
-      if (!distingushRuleSet.add(pls)) {
-        throw new IOException("Invalid PlacementRule inputs which "
-            + "contains duplicate rule strings");
-      }
-    }
+    Set<String> distinguishRuleSet = CapacitySchedulerConfigValidator
+            .validatePlacementRules(placementRuleStrs);
 
     // add UserGroupMappingPlacementRule if absent
-    distingushRuleSet.add(YarnConfiguration.USER_GROUP_PLACEMENT_RULE);
+    distinguishRuleSet.add(YarnConfiguration.USER_GROUP_PLACEMENT_RULE);
 
-    placementRuleStrs = new ArrayList<>(distingushRuleSet);
+    placementRuleStrs = new ArrayList<>(distinguishRuleSet);
 
     for (String placementRuleStr : placementRuleStrs) {
       switch (placementRuleStr) {

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/CapacitySchedulerConfigValidator.java

@@ -0,0 +1,190 @@
+/**
+ * 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.hadoop.yarn.server.resourcemanager.scheduler.capacity;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.yarn.api.records.QueueState;
+import org.apache.hadoop.yarn.conf.YarnConfiguration;
+import org.apache.hadoop.yarn.exceptions.YarnRuntimeException;
+import org.apache.hadoop.yarn.server.resourcemanager.RMContext;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.IOException;
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+
+public final class CapacitySchedulerConfigValidator {
+  private static final Logger LOG = LoggerFactory.getLogger(
+          CapacitySchedulerConfigValidator.class);
+
+  private CapacitySchedulerConfigValidator() {
+    throw new IllegalStateException("Utility class");
+  }
+
+  public static boolean validateCSConfiguration(
+          final Configuration oldConf, final Configuration newConf,
+         final RMContext rmContext) throws IOException {
+    //TODO: extract all the validation steps and replace reinitialize with
+    //the specific validation steps
+    CapacityScheduler newCs = new CapacityScheduler();
+    newCs.setConf(oldConf);
+    newCs.setRMContext(rmContext);
+    newCs.init(oldConf);
+    newCs.reinitialize(newConf, rmContext, true);
+    return true;
+  }
+
+  public static Set<String> validatePlacementRules(
+          Collection<String> placementRuleStrs) throws IOException {
+    Set<String> distinguishRuleSet = new HashSet<>();
+    // fail the case if we get duplicate placementRule add in
+    for (String pls : placementRuleStrs) {
+      if (!distinguishRuleSet.add(pls)) {
+        throw new IOException("Invalid PlacementRule inputs which "
+                + "contains duplicate rule strings");
+      }
+    }
+    return distinguishRuleSet;
+  }
+
+  public static void validateMemoryAllocation(Configuration conf) {
+    int minMem = conf.getInt(
+            YarnConfiguration.RM_SCHEDULER_MINIMUM_ALLOCATION_MB,
+            YarnConfiguration.DEFAULT_RM_SCHEDULER_MINIMUM_ALLOCATION_MB);
+    int maxMem = conf.getInt(
+            YarnConfiguration.RM_SCHEDULER_MAXIMUM_ALLOCATION_MB,
+            YarnConfiguration.DEFAULT_RM_SCHEDULER_MAXIMUM_ALLOCATION_MB);
+
+    if (minMem <= 0 || minMem > maxMem) {
+      throw new YarnRuntimeException("Invalid resource scheduler memory"
+              + " allocation configuration"
+              + ", " + YarnConfiguration.RM_SCHEDULER_MINIMUM_ALLOCATION_MB
+              + "=" + minMem
+              + ", " + YarnConfiguration.RM_SCHEDULER_MAXIMUM_ALLOCATION_MB
+              + "=" + maxMem + ", min and max should be greater than 0"
+              + ", max should be no smaller than min.");
+    }
+  }
+  public static void validateVCores(Configuration conf) {
+    int minVcores = conf.getInt(
+            YarnConfiguration.RM_SCHEDULER_MINIMUM_ALLOCATION_VCORES,
+            YarnConfiguration.DEFAULT_RM_SCHEDULER_MINIMUM_ALLOCATION_VCORES);
+    int maxVcores = conf.getInt(
+            YarnConfiguration.RM_SCHEDULER_MAXIMUM_ALLOCATION_VCORES,
+            YarnConfiguration.DEFAULT_RM_SCHEDULER_MAXIMUM_ALLOCATION_VCORES);
+
+    if (minVcores <= 0 || minVcores > maxVcores) {
+      throw new YarnRuntimeException("Invalid resource scheduler vcores"
+              + " allocation configuration"
+              + ", " + YarnConfiguration.RM_SCHEDULER_MINIMUM_ALLOCATION_VCORES
+              + "=" + minVcores
+              + ", " + YarnConfiguration.RM_SCHEDULER_MAXIMUM_ALLOCATION_VCORES
+              + "=" + maxVcores + ", min and max should be greater than 0"
+              + ", max should be no smaller than min.");
+    }
+  }
+
+  /**
+   * Ensure all existing queues are present. Queues cannot be deleted if its not
+   * in Stopped state, Queue's cannot be moved from one hierarchy to other also.
+   * Previous child queue could be converted into parent queue if it is in
+   * STOPPED state.
+   *
+   * @param queues existing queues
+   * @param newQueues new queues
+   */
+  public static void validateQueueHierarchy(Map<String, CSQueue> queues,
+         Map<String, CSQueue> newQueues, CapacitySchedulerConfiguration newConf)
+         throws IOException {
+    // check that all static queues are included in the newQueues list
+    for (Map.Entry<String, CSQueue> e : queues.entrySet()) {
+      if (!(AbstractAutoCreatedLeafQueue.class.isAssignableFrom(e.getValue()
+              .getClass()))) {
+        String queueName = e.getKey();
+        CSQueue oldQueue = e.getValue();
+        CSQueue newQueue = newQueues.get(queueName);
+        if (null == newQueue) {
+          // old queue doesn't exist in the new XML
+          String configPrefix = newConf.getQueuePrefix(
+                  oldQueue.getQueuePath());
+          QueueState newQueueState = null;
+          try {
+            newQueueState = QueueState.valueOf(
+                    newConf.get(configPrefix + "state"));
+          } catch (Exception ex) {
+            LOG.warn("Not a valid queue state for queue "
+                    + oldQueue.getQueuePath());
+          }
+          if (oldQueue.getState() == QueueState.STOPPED ||
+                  newQueueState == QueueState.STOPPED) {
+            LOG.info("Deleting Queue " + queueName + ", as it is not"
+                    + " present in the modified capacity configuration xml");
+          } else{
+            throw new IOException(oldQueue.getQueuePath() + " cannot be"
+                    + " deleted from the capacity scheduler configuration, "
+                    + "as the queue is not yet in stopped state. "
+                    + "Current State : " + oldQueue.getState());
+          }
+        } else if (!oldQueue.getQueuePath().equals(newQueue.getQueuePath())) {
+          //Queue's cannot be moved from one hierarchy to other
+          throw new IOException(
+                  queueName + " is moved from:" + oldQueue.getQueuePath()
+                          + " to:" + newQueue.getQueuePath()
+                          + " after refresh, which is not allowed.");
+        } else if (oldQueue instanceof ParentQueue
+                && !(oldQueue instanceof ManagedParentQueue)
+                && newQueue instanceof ManagedParentQueue) {
+          throw new IOException(
+                  "Can not convert parent queue: " + oldQueue.getQueuePath()
+                          + " to auto create enabled parent queue since "
+                          + "it could have other pre-configured queues which is"
+                          + " not supported");
+        } else if (oldQueue instanceof ManagedParentQueue
+                && !(newQueue instanceof ManagedParentQueue)) {
+          throw new IOException(
+                  "Cannot convert auto create enabled parent queue: " + oldQueue
+                          .getQueuePath() + " to leaf queue. Please check "
+                          + " parent queue's configuration "
+                          + CapacitySchedulerConfiguration
+                          .AUTO_CREATE_CHILD_QUEUE_ENABLED
+                          + " is set to true");
+        } else if (oldQueue instanceof LeafQueue
+                && newQueue instanceof ParentQueue) {
+          if (oldQueue.getState() == QueueState.STOPPED) {
+            LOG.info("Converting the leaf queue: " + oldQueue.getQueuePath()
+                    + " to parent queue.");
+          } else{
+            throw new IOException(
+                    "Can not convert the leaf queue: " + oldQueue.getQueuePath()
+                            + " to parent queue since "
+                            + "it is not yet in stopped state. Current State : "
+                            + oldQueue.getState());
+          }
+        } else if (oldQueue instanceof ParentQueue
+                && newQueue instanceof LeafQueue) {
+          LOG.info("Converting the parent queue: " + oldQueue.getQueuePath()
+                  + " to leaf queue.");
+        }
+      }
+    }
+  }
+}

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/CapacitySchedulerQueueManager.java

@@ -36,7 +36,6 @@ import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.ha.HAServiceProtocol;
 import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.yarn.api.records.Priority;
-import org.apache.hadoop.yarn.api.records.QueueState;
 import org.apache.hadoop.yarn.api.records.Resource;
 import org.apache.hadoop.yarn.exceptions.YarnException;
 import org.apache.hadoop.yarn.security.Permission;
@@ -177,7 +176,8 @@ public class CapacitySchedulerQueueManager implements SchedulerQueueManager<
         csContext.getRMContext().getHAServiceState()
             != HAServiceProtocol.HAServiceState.STANDBY) {
       // Ensure queue hierarchy in the new XML file is proper.
-      validateQueueHierarchy(queues, newQueues);
+      CapacitySchedulerConfigValidator
+              .validateQueueHierarchy(queues, newQueues, newConf);
     }
 
     // Add new queues and delete OldQeueus only after validation.
@@ -299,78 +299,6 @@ public class CapacitySchedulerQueueManager implements SchedulerQueueManager<
     return queue;
   }
 
-  /**
-   * Ensure all existing queues are present. Queues cannot be deleted if its not
-   * in Stopped state, Queue's cannot be moved from one hierarchy to other also.
-   * Previous child queue could be converted into parent queue if it is in
-   * STOPPED state.
-   *
-   * @param queues existing queues
-   * @param newQueues new queues
-   */
-  private void validateQueueHierarchy(Map<String, CSQueue> queues,
-      Map<String, CSQueue> newQueues) throws IOException {
-    // check that all static queues are included in the newQueues list
-    for (Map.Entry<String, CSQueue> e : queues.entrySet()) {
-      if (!(AbstractAutoCreatedLeafQueue.class.isAssignableFrom(e.getValue()
-          .getClass()))) {
-        String queueName = e.getKey();
-        CSQueue oldQueue = e.getValue();
-        CSQueue newQueue = newQueues.get(queueName);
-        if (null == newQueue) {
-          // old queue doesn't exist in the new XML
-          if (oldQueue.getState() == QueueState.STOPPED) {
-            LOG.info("Deleting Queue " + queueName + ", as it is not"
-                + " present in the modified capacity configuration xml");
-          } else{
-            throw new IOException(oldQueue.getQueuePath() + " is deleted from"
-                + " the new capacity scheduler configuration, but the"
-                + " queue is not yet in stopped state. " + "Current State : "
-                + oldQueue.getState());
-          }
-        } else if (!oldQueue.getQueuePath().equals(newQueue.getQueuePath())) {
-          //Queue's cannot be moved from one hierarchy to other
-          throw new IOException(
-              queueName + " is moved from:" + oldQueue.getQueuePath() + " to:"
-                  + newQueue.getQueuePath()
-                  + " after refresh, which is not allowed.");
-        } else if (oldQueue instanceof ParentQueue
-            && !(oldQueue instanceof ManagedParentQueue)
-            && newQueue instanceof ManagedParentQueue) {
-          throw new IOException(
-              "Can not convert parent queue: " + oldQueue.getQueuePath()
-                  + " to auto create enabled parent queue since "
-                  + "it could have other pre-configured queues which is not "
-                  + "supported");
-        } else if (oldQueue instanceof ManagedParentQueue
-            && !(newQueue instanceof ManagedParentQueue)) {
-          throw new IOException(
-              "Cannot convert auto create enabled parent queue: " + oldQueue
-                  .getQueuePath() + " to leaf queue. Please check "
-                  + " parent queue's configuration "
-                  + CapacitySchedulerConfiguration
-                  .AUTO_CREATE_CHILD_QUEUE_ENABLED
-                  + " is set to true");
-        } else if (oldQueue instanceof LeafQueue
-            && newQueue instanceof ParentQueue) {
-          if (oldQueue.getState() == QueueState.STOPPED) {
-            LOG.info("Converting the leaf queue: " + oldQueue.getQueuePath()
-                + " to parent queue.");
-          } else{
-            throw new IOException(
-                "Can not convert the leaf queue: " + oldQueue.getQueuePath()
-                    + " to parent queue since "
-                    + "it is not yet in stopped state. Current State : "
-                    + oldQueue.getState());
-          }
-        } else if (oldQueue instanceof ParentQueue
-            && newQueue instanceof LeafQueue) {
-          LOG.info("Converting the parent queue: " + oldQueue.getQueuePath()
-              + " to leaf queue.");
-        }
-      }
-    }
-  }
 
   /**
    * Updates to our list of queues: Adds the new queues and deletes the removed

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/conf/MutableCSConfigurationProvider.java

@@ -131,14 +131,32 @@ public class MutableCSConfigurationProvider implements CSConfigurationProvider,
   public void logAndApplyMutation(UserGroupInformation user,
       SchedConfUpdateInfo confUpdate) throws Exception {
     oldConf = new Configuration(schedConf);
-    Map<String, String> kvUpdate = constructKeyValueConfUpdate(confUpdate);
+    CapacitySchedulerConfiguration proposedConf =
+            new CapacitySchedulerConfiguration(schedConf, false);
+    Map<String, String> kvUpdate
+            = constructKeyValueConfUpdate(proposedConf, confUpdate);
     LogMutation log = new LogMutation(kvUpdate, user.getShortUserName());
     confStore.logMutation(log);
+    applyMutation(proposedConf, kvUpdate);
+    schedConf = proposedConf;
+  }
+
+  public Configuration applyChanges(Configuration oldConfiguration,
+                           SchedConfUpdateInfo confUpdate) throws IOException {
+    CapacitySchedulerConfiguration proposedConf =
+            new CapacitySchedulerConfiguration(oldConfiguration, false);
+    Map<String, String> kvUpdate
+            = constructKeyValueConfUpdate(proposedConf, confUpdate);
+    applyMutation(proposedConf, kvUpdate);
+    return proposedConf;
+  }
+
+  private void applyMutation(Configuration conf, Map<String, String> kvUpdate) {
     for (Map.Entry<String, String> kv : kvUpdate.entrySet()) {
       if (kv.getValue() == null) {
-        schedConf.unset(kv.getKey());
+        conf.unset(kv.getKey());
       } else {
-        schedConf.set(kv.getKey(), kv.getValue());
+        conf.set(kv.getKey(), kv.getValue());
       }
     }
   }
@@ -215,9 +233,9 @@ public class MutableCSConfigurationProvider implements CSConfigurationProvider,
   }
 
   private Map<String, String> constructKeyValueConfUpdate(
+      CapacitySchedulerConfiguration proposedConf,
       SchedConfUpdateInfo mutationInfo) throws IOException {
-    CapacitySchedulerConfiguration proposedConf =
-        new CapacitySchedulerConfiguration(schedConf, false);
+
     Map<String, String> confUpdate = new HashMap<>();
     for (String queueToRemove : mutationInfo.getRemoveQueueInfo()) {
       removeQueue(queueToRemove, proposedConf, confUpdate);

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/RMWSConsts.java

@@ -57,6 +57,12 @@ public final class RMWSConsts {
   /** Path for {@code RMWebServiceProtocol#dumpSchedulerLogs}. */
   public static final String SCHEDULER_LOGS = "/scheduler/logs";
 
+  /**
+   * Path for {@code RMWebServiceProtocol#validateAndGetSchedulerConfiguration}.
+   */
+  public static final String SCHEDULER_CONF_VALIDATE
+          = "/scheduler-conf/validate";
+
   /** Path for {@code RMWebServiceProtocol#getNodes}. */
   public static final String NODES = "/nodes";
 

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/RMWebServices.java

@@ -141,6 +141,7 @@ import org.apache.hadoop.yarn.server.resourcemanager.scheduler.ResourceScheduler
 import org.apache.hadoop.yarn.server.resourcemanager.scheduler.YarnScheduler;
 import org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CSQueue;
 import org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler;
+import org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacitySchedulerConfigValidator;
 import org.apache.hadoop.yarn.server.resourcemanager.scheduler.common.fica.FiCaSchedulerNode;
 import org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.FairScheduler;
 import org.apache.hadoop.yarn.server.resourcemanager.scheduler.fifo.FifoScheduler;
@@ -2370,6 +2371,53 @@ public class RMWebServices extends WebServices implements RMWebServiceProtocol {
     }
   }
 
+  @POST
+  @Path(RMWSConsts.SCHEDULER_CONF_VALIDATE)
+  @Produces({ MediaType.APPLICATION_JSON + "; " + JettyUtils.UTF_8,
+          MediaType.APPLICATION_XML + "; " + JettyUtils.UTF_8 })
+  @Consumes({ MediaType.APPLICATION_JSON, MediaType.APPLICATION_XML })
+  public synchronized Response validateAndGetSchedulerConfiguration(
+          SchedConfUpdateInfo mutationInfo,
+          @Context HttpServletRequest hsr) throws AuthorizationException {
+    // Only admin user is allowed to read scheduler conf,
+    // in order to avoid leaking sensitive info, such as ACLs
+    UserGroupInformation callerUGI = getCallerUserGroupInformation(hsr, true);
+    initForWritableEndpoints(callerUGI, true);
+    ResourceScheduler scheduler = rm.getResourceScheduler();
+    if (scheduler instanceof MutableConfScheduler && ((MutableConfScheduler)
+            scheduler).isConfigurationMutable()) {
+      try {
+        MutableConfigurationProvider mutableConfigurationProvider =
+                ((MutableConfScheduler) scheduler).getMutableConfProvider();
+        Configuration schedulerConf = mutableConfigurationProvider
+                .getConfiguration();
+        Configuration newConfig = mutableConfigurationProvider
+                .applyChanges(schedulerConf, mutationInfo);
+        Configuration yarnConf = ((CapacityScheduler) scheduler).getConf();
+        CapacitySchedulerConfigValidator.validateCSConfiguration(yarnConf,
+                newConfig, rm.getRMContext());
+
+        return Response.status(Status.OK)
+                .entity(new ConfInfo(newConfig))
+                .build();
+      } catch (Exception e) {
+        String errorMsg = "CapacityScheduler configuration validation failed:"
+                  + e.toString();
+        LOG.warn(errorMsg);
+        return Response.status(Status.BAD_REQUEST)
+                  .entity(errorMsg)
+                  .build();
+      }
+    } else {
+      String errorMsg = "Configuration change validation only supported by " +
+              "MutableConfScheduler.";
+      LOG.warn(errorMsg);
+      return Response.status(Status.BAD_REQUEST)
+              .entity(errorMsg)
+              .build();
+    }
+  }
+
   @PUT
   @Path(RMWSConsts.SCHEDULER_CONF)
   @Produces({ MediaType.APPLICATION_JSON + "; " + JettyUtils.UTF_8,

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/CapacitySchedulerConfigGeneratorForTest.java

@@ -0,0 +1,53 @@
+/**
+ * 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.hadoop.yarn.server.resourcemanager.scheduler.capacity;
+
+import org.apache.hadoop.conf.Configuration;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public final class CapacitySchedulerConfigGeneratorForTest {
+
+  private CapacitySchedulerConfigGeneratorForTest() {
+    throw new IllegalStateException("Utility class");
+  }
+
+  public static Configuration createConfiguration(Map<String, String> configs) {
+    Configuration config = new Configuration();
+    for (Map.Entry entry: configs.entrySet()) {
+      config.set((String)entry.getKey(), (String)entry.getValue());
+    }
+    return config;
+  }
+
+  public static Configuration createBasicCSConfiguration() {
+    Map<String, String> conf = new HashMap<>();
+    conf.put("yarn.scheduler.capacity.root.queues", "test1, test2");
+    conf.put("yarn.scheduler.capacity.root.test1.capacity", "50");
+    conf.put("yarn.scheduler.capacity.root.test2.capacity", "50");
+    conf.put("yarn.scheduler.capacity.root.test1.maximum-capacity", "100");
+    conf.put("yarn.scheduler.capacity.root.test1.state", "RUNNING");
+    conf.put("yarn.scheduler.capacity.root.test2.state", "RUNNING");
+    conf.put("yarn.scheduler.capacity.queue-mappings",
+            "u:test1:test1,u:test2:test2");
+    return createConfiguration(conf);
+  }
+
+}

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/TestCapacitySchedulerConfigValidator.java

@@ -0,0 +1,366 @@
+/**
+ * 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.hadoop.yarn.server.resourcemanager.scheduler.capacity;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.yarn.LocalConfigurationProvider;
+import org.apache.hadoop.yarn.api.records.impl.LightWeightResource;
+import org.apache.hadoop.yarn.conf.YarnConfiguration;
+import org.apache.hadoop.yarn.exceptions.YarnRuntimeException;
+import org.apache.hadoop.yarn.server.resourcemanager.RMContext;
+import org.apache.hadoop.yarn.server.resourcemanager.nodelabels.RMNodeLabelsManager;
+import org.apache.hadoop.yarn.server.resourcemanager.placement.PlacementManager;
+import org.junit.Assert;
+import org.junit.Test;
+import org.mockito.Mockito;
+
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
+
+import static org.junit.Assert.fail;
+
+public class TestCapacitySchedulerConfigValidator {
+
+  /**
+   * Test for the case when the scheduler.minimum-allocation-mb == 0.
+   */
+  @Test (expected = YarnRuntimeException.class)
+  public void testValidateMemoryAllocationInvalidMinMem() {
+    Map<String, String> configs = new HashMap();
+    configs.put(YarnConfiguration.RM_SCHEDULER_MINIMUM_ALLOCATION_MB, "0");
+    Configuration config = CapacitySchedulerConfigGeneratorForTest
+            .createConfiguration(configs);
+    CapacitySchedulerConfigValidator.validateMemoryAllocation(config);
+    fail(YarnConfiguration.RM_SCHEDULER_MINIMUM_ALLOCATION_MB +
+            " should be > 0");
+  }
+
+  /**
+   * Test for the case when the scheduler.minimum-allocation-mb is greater than
+   * scheduler.maximum-allocation-mb.
+   */
+  @Test (expected = YarnRuntimeException.class)
+  public void testValidateMemoryAllocationHIgherMinThanMaxMem() {
+    Map<String, String> configs = new HashMap();
+    configs.put(YarnConfiguration.RM_SCHEDULER_MINIMUM_ALLOCATION_MB, "8192");
+    configs.put(YarnConfiguration.RM_SCHEDULER_MAXIMUM_ALLOCATION_MB, "1024");
+    Configuration config = CapacitySchedulerConfigGeneratorForTest
+            .createConfiguration(configs);
+    CapacitySchedulerConfigValidator.validateMemoryAllocation(config);
+    fail(YarnConfiguration.RM_SCHEDULER_MINIMUM_ALLOCATION_MB + " should be > "
+            + YarnConfiguration.RM_SCHEDULER_MAXIMUM_ALLOCATION_MB);
+
+  }
+
+
+  @Test
+  public void testValidateMemoryAllocation() {
+    Map<String, String> configs = new HashMap();
+    configs.put(YarnConfiguration.RM_SCHEDULER_MINIMUM_ALLOCATION_MB, "1024");
+    configs.put(YarnConfiguration.RM_SCHEDULER_MAXIMUM_ALLOCATION_MB, "8192");
+    Configuration config = CapacitySchedulerConfigGeneratorForTest
+            .createConfiguration(configs);
+    // there is no need for assertion, since there is no further method call
+    // inside the tested code and in case of a valid configuration no exception
+    // is thrown
+    CapacitySchedulerConfigValidator.validateMemoryAllocation(config);
+  }
+
+  /**
+   * Test for the case when the scheduler.minimum-allocation-vcores == 0.
+   */
+  @Test (expected = YarnRuntimeException.class)
+  public void testValidateVCoresInvalidMinVCore() {
+    Map<String, String> configs = new HashMap();
+    configs.put(YarnConfiguration.RM_SCHEDULER_MINIMUM_ALLOCATION_VCORES, "0");
+    Configuration config = CapacitySchedulerConfigGeneratorForTest
+            .createConfiguration(configs);
+    CapacitySchedulerConfigValidator.validateVCores(config);
+    fail(YarnConfiguration.RM_SCHEDULER_MINIMUM_ALLOCATION_VCORES
+            + " should be > 0");
+  }
+
+  /**
+   * Test for the case when the scheduler.minimum-allocation-vcores is greater
+   * than scheduler.maximum-allocation-vcores.
+   */
+  @Test (expected = YarnRuntimeException.class)
+  public void testValidateVCoresHigherMinThanMaxVCore() {
+    Map<String, String> configs = new HashMap();
+    configs.put(YarnConfiguration.RM_SCHEDULER_MINIMUM_ALLOCATION_VCORES, "4");
+    configs.put(YarnConfiguration.RM_SCHEDULER_MAXIMUM_ALLOCATION_VCORES, "1");
+    Configuration config = CapacitySchedulerConfigGeneratorForTest
+            .createConfiguration(configs);
+    CapacitySchedulerConfigValidator.validateVCores(config);
+    fail(YarnConfiguration.RM_SCHEDULER_MINIMUM_ALLOCATION_VCORES +
+            " should be > "
+            + YarnConfiguration.RM_SCHEDULER_MAXIMUM_ALLOCATION_MB);
+
+  }
+
+
+  @Test
+  public void testValidateVCores() {
+    Map<String, String> configs = new HashMap();
+    configs.put(YarnConfiguration.RM_SCHEDULER_MINIMUM_ALLOCATION_VCORES, "1");
+    configs.put(YarnConfiguration.RM_SCHEDULER_MAXIMUM_ALLOCATION_VCORES, "4");
+    Configuration config = CapacitySchedulerConfigGeneratorForTest
+            .createConfiguration(configs);
+    // there is no need for assertion, since there is no further method call
+    // inside the tested code and in case of a valid configuration no exception
+    // is thrown
+    CapacitySchedulerConfigValidator.validateVCores(config);
+  }
+
+  @Test
+  public void testValidateCSConfigInvalidCapacity() {
+    Configuration oldConfig = CapacitySchedulerConfigGeneratorForTest
+            .createBasicCSConfiguration();
+    Configuration newConfig = new Configuration(oldConfig);
+    newConfig
+            .set("yarn.scheduler.capacity.root.test1.capacity", "500");
+    RMContext rmContext = prepareRMContext();
+    try {
+      CapacitySchedulerConfigValidator
+              .validateCSConfiguration(oldConfig, newConfig, rmContext);
+      fail("Invalid capacity");
+    } catch (IOException e) {
+      Assert.assertTrue(e.getCause().getMessage()
+              .startsWith("Illegal capacity"));
+    }
+  }
+
+  @Test
+  public void testValidateCSConfigStopALeafQueue() throws IOException {
+    Configuration oldConfig = CapacitySchedulerConfigGeneratorForTest
+            .createBasicCSConfiguration();
+    Configuration newConfig = new Configuration(oldConfig);
+    newConfig
+            .set("yarn.scheduler.capacity.root.test1.state", "STOPPED");
+    RMContext rmContext = prepareRMContext();
+    Boolean isValidConfig = CapacitySchedulerConfigValidator
+            .validateCSConfiguration(oldConfig, newConfig, rmContext);
+    Assert.assertTrue(isValidConfig);
+  }
+
+  /**
+   * Stop the root queue if there are running child queues.
+   */
+  @Test
+  public void testValidateCSConfigStopANonLeafQueueInvalid() {
+    Configuration oldConfig = CapacitySchedulerConfigGeneratorForTest
+            .createBasicCSConfiguration();
+    Configuration newConfig = new Configuration(oldConfig);
+    newConfig
+            .set("yarn.scheduler.capacity.root.state", "STOPPED");
+    RMContext rmContext = prepareRMContext();
+    try {
+      CapacitySchedulerConfigValidator
+              .validateCSConfiguration(oldConfig, newConfig, rmContext);
+      fail("There are child queues in running state");
+    } catch (IOException e) {
+      // TODO: change the assertion message in case of backporting YARN-8678
+      Assert.assertTrue(e.getCause().getMessage()
+              .contains("The parent queue:root state is STOPPED,"
+                      + " child queue:test1 state cannot be RUNNING"));
+    }
+  }
+
+  @Test
+  public void testValidateCSConfigStopANonLeafQueue() throws IOException {
+    Configuration oldConfig = CapacitySchedulerConfigGeneratorForTest
+            .createBasicCSConfiguration();
+    Configuration newConfig = new Configuration(oldConfig);
+    newConfig
+            .set("yarn.scheduler.capacity.root.state", "STOPPED");
+    newConfig
+            .set("yarn.scheduler.capacity.root.test1.state", "STOPPED");
+    newConfig
+            .set("yarn.scheduler.capacity.root.test2.state", "STOPPED");
+    RMContext rmContext = prepareRMContext();
+    Boolean isValidConfig = CapacitySchedulerConfigValidator
+            .validateCSConfiguration(oldConfig, newConfig, rmContext);
+    Assert.assertTrue(isValidConfig);
+
+  }
+
+  /**
+   * Add a leaf queue without modifying the capacity of other leaf queues
+   * so the total capacity != 100.
+   */
+  @Test
+  public void testValidateCSConfigAddALeafQueueInvalid() {
+    Configuration oldConfig = CapacitySchedulerConfigGeneratorForTest
+            .createBasicCSConfiguration();
+    Configuration newConfig = new Configuration(oldConfig);
+    newConfig
+            .set("yarn.scheduler.capacity.root.queues", "test1, test2, test3");
+    newConfig
+            .set("yarn.scheduler.capacity.root.test3.state", "RUNNING");
+    newConfig
+            .set("yarn.scheduler.capacity.root.test3.capacity", "30");
+
+    RMContext rmContext = prepareRMContext();
+    try {
+      CapacitySchedulerConfigValidator
+              .validateCSConfiguration(oldConfig, newConfig, rmContext);
+      fail("Invalid capacity for children of queue root");
+    } catch (IOException e) {
+      Assert.assertTrue(e.getCause().getMessage()
+              .startsWith("Illegal capacity"));
+    }
+  }
+
+  /**
+   * Add a leaf queue by modifying the capacity of other leaf queues
+   * and adjust the capacities of other leaf queues, so total capacity = 100.
+   */
+  @Test
+  public void testValidateCSConfigAddALeafQueueValid() throws IOException {
+    Configuration oldConfig = CapacitySchedulerConfigGeneratorForTest
+            .createBasicCSConfiguration();
+    Configuration newConfig = new Configuration(oldConfig);
+    newConfig
+            .set("yarn.scheduler.capacity.root.queues", "test1, test2, test3");
+    newConfig
+            .set("yarn.scheduler.capacity.root.test3.state", "RUNNING");
+    newConfig
+            .set("yarn.scheduler.capacity.root.test3.capacity", "30");
+    newConfig
+            .set("yarn.scheduler.capacity.root.test1.capacity", "20");
+
+    RMContext rmContext = prepareRMContext();
+    Boolean isValidConfig = CapacitySchedulerConfigValidator
+            .validateCSConfiguration(oldConfig, newConfig, rmContext);
+    Assert.assertTrue(isValidConfig);
+  }
+
+  /**
+   * Delete a running queue.
+   */
+  @Test
+  public void testValidateCSConfigInvalidQueueDeletion() {
+    Configuration oldConfig = CapacitySchedulerConfigGeneratorForTest
+            .createBasicCSConfiguration();
+    Configuration newConfig = new Configuration(oldConfig);
+    newConfig.set("yarn.scheduler.capacity.root.queues", "test1");
+    newConfig.set("yarn.scheduler.capacity.root.test1.capacity", "100");
+    newConfig.unset("yarn.scheduler.capacity.root.test2.maximum-capacity");
+    newConfig.unset("yarn.scheduler.capacity.root.test2.state");
+    newConfig.set("yarn.scheduler.capacity.queue-mappings",
+            "u:test1:test1");
+    RMContext rmContext = prepareRMContext();
+    try {
+      CapacitySchedulerConfigValidator
+              .validateCSConfiguration(oldConfig, newConfig, rmContext);
+      fail("Invalid capacity for children of queue root");
+    } catch (IOException e) {
+      Assert.assertTrue(e.getCause().getMessage()
+              .contains("root.test2 cannot be deleted"));
+      Assert.assertTrue(e.getCause().getMessage()
+              .contains("the queue is not yet in stopped state"));
+    }
+  }
+
+  /**
+   * Delete a queue and not adjust capacities.
+   */
+  @Test
+  public void testValidateCSConfigInvalidQueueDeletion2() {
+    Configuration oldConfig = CapacitySchedulerConfigGeneratorForTest
+            .createBasicCSConfiguration();
+    Configuration newConfig = new Configuration(oldConfig);
+    newConfig.set("yarn.scheduler.capacity.root.queues", "test1");
+    newConfig.unset("yarn.scheduler.capacity.root.test2.maximum-capacity");
+    newConfig.unset("yarn.scheduler.capacity.root.test2.state");
+    newConfig.set("yarn.scheduler.capacity.queue-mappings",
+            "u:test1:test1");
+    RMContext rmContext = prepareRMContext();
+    try {
+      CapacitySchedulerConfigValidator
+              .validateCSConfiguration(oldConfig, newConfig, rmContext);
+      fail("Invalid capacity for children of queue root");
+    } catch (IOException e) {
+      Assert.assertTrue(e.getCause().getMessage()
+              .contains("Illegal capacity"));
+    }
+  }
+
+  /**
+   * Delete a queue and adjust capacities to have total capacity = 100.
+   */
+  @Test
+  public void testValidateCSConfigValidQueueDeletion() throws IOException {
+    Configuration oldConfig = CapacitySchedulerConfigGeneratorForTest
+            .createBasicCSConfiguration();
+    oldConfig.set("yarn.scheduler.capacity.root.test2.state", "STOPPED");
+    Configuration newConfig = new Configuration(oldConfig);
+    newConfig.set("yarn.scheduler.capacity.root.queues", "test1");
+    newConfig.set("yarn.scheduler.capacity.root.test1.capacity", "100");
+    newConfig.unset("yarn.scheduler.capacity.root.test2.maximum-capacity");
+    newConfig.unset("yarn.scheduler.capacity.root.test2.state");
+    newConfig.set("yarn.scheduler.capacity.queue-mappings",
+            "u:test1:test1");
+    RMContext rmContext = prepareRMContext();
+    boolean isValidConfig = CapacitySchedulerConfigValidator
+              .validateCSConfiguration(oldConfig, newConfig, rmContext);
+    Assert.assertTrue(isValidConfig);
+
+  }
+
+  @Test
+  public void testAddQueueToALeafQueue() throws IOException {
+    Configuration oldConfig = CapacitySchedulerConfigGeneratorForTest
+            .createBasicCSConfiguration();
+    oldConfig.set("yarn.scheduler.capacity.root.test1.state", "STOPPED");
+    Configuration newConfig = new Configuration(oldConfig);
+    newConfig.set("yarn.scheduler.capacity.root.test1.queues", "newQueue");
+    newConfig
+            .set("yarn.scheduler.capacity.root.test1.newQueue.capacity", "100");
+    newConfig.set("yarn.scheduler.capacity.queue-mappings",
+            "u:test1:test2");
+    RMContext rmContext = prepareRMContext();
+    boolean isValidConfig = CapacitySchedulerConfigValidator
+            .validateCSConfiguration(oldConfig, newConfig, rmContext);
+    Assert.assertTrue(isValidConfig);
+  }
+
+
+  public static RMContext prepareRMContext() {
+    RMContext rmContext = Mockito.mock(RMContext.class);
+    LocalConfigurationProvider configProvider = Mockito
+            .mock(LocalConfigurationProvider.class);
+    Mockito.when(rmContext.getConfigurationProvider())
+            .thenReturn(configProvider);
+    RMNodeLabelsManager nodeLabelsManager = Mockito
+            .mock(RMNodeLabelsManager.class);
+    Mockito.when(rmContext.getNodeLabelManager()).thenReturn(nodeLabelsManager);
+    LightWeightResource partitionResource = Mockito
+            .mock(LightWeightResource.class);
+    Mockito.when(nodeLabelsManager
+            .getResourceByLabel(Mockito.any(), Mockito.any()))
+            .thenReturn(partitionResource);
+    PlacementManager queuePlacementManager = Mockito
+            .mock(PlacementManager.class);
+    Mockito.when(rmContext.getQueuePlacementManager())
+            .thenReturn(queuePlacementManager);
+    return rmContext;
+  }
+}

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/TestRMWebServices.java

@@ -22,15 +22,20 @@ import static org.apache.hadoop.yarn.webapp.WebServicesTestUtils.assertResponseS
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
+import static org.mockito.Matchers.any;
 import static org.mockito.Matchers.isA;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 
 import java.io.File;
+import java.io.IOException;
 import java.io.StringReader;
 import java.security.Principal;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
 import java.util.Set;
 
 import javax.servlet.http.HttpServletRequest;
@@ -45,6 +50,7 @@ import org.apache.commons.io.FileUtils;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.http.JettyUtils;
 import org.apache.hadoop.security.UserGroupInformation;
+import org.apache.hadoop.security.authorize.AuthorizationException;
 import org.apache.hadoop.service.Service.STATE;
 import org.apache.hadoop.util.VersionInfo;
 import org.apache.hadoop.yarn.api.protocolrecords.GetApplicationsRequest;
@@ -59,6 +65,9 @@ import org.apache.hadoop.yarn.server.resourcemanager.nodelabels.RMNodeLabelsMana
 import org.apache.hadoop.yarn.server.resourcemanager.scheduler.QueueMetrics;
 import org.apache.hadoop.yarn.server.resourcemanager.scheduler.ResourceScheduler;
 import org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler;
+import org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacitySchedulerConfigGeneratorForTest;
+import org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.TestCapacitySchedulerConfigValidator;
+import org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.conf.MutableCSConfigurationProvider;
 import org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.FairScheduler;
 import org.apache.hadoop.yarn.server.resourcemanager.scheduler.fifo.FifoScheduler;
 import org.apache.hadoop.yarn.server.resourcemanager.webapp.dao.ApplicationSubmissionContextInfo;
@@ -73,6 +82,8 @@ import org.apache.hadoop.yarn.webapp.GenericExceptionHandler;
 import org.apache.hadoop.yarn.webapp.GuiceServletConfig;
 import org.apache.hadoop.yarn.webapp.JerseyTestBase;
 import org.apache.hadoop.yarn.webapp.WebServicesTestUtils;
+import org.apache.hadoop.yarn.webapp.dao.QueueConfigInfo;
+import org.apache.hadoop.yarn.webapp.dao.SchedConfUpdateInfo;
 import org.codehaus.jettison.json.JSONException;
 import org.codehaus.jettison.json.JSONObject;
 import org.junit.Assert;
@@ -884,4 +895,112 @@ public class TestRMWebServices extends JerseyTestBase {
     assertEquals("requestedUser doesn't match: ",
             requestedUser, userInfo.getRequestedUser());
   }
+
+  @Test
+  public void testValidateAndGetSchedulerConfigurationInvalidScheduler()
+          throws AuthorizationException {
+    ResourceScheduler scheduler = new CapacityScheduler();
+    RMWebServices webService = prepareWebServiceForValidation(scheduler);
+    SchedConfUpdateInfo mutationInfo = new SchedConfUpdateInfo();
+    HttpServletRequest mockHsr = prepareServletRequestForValidation();
+    Response response = webService
+            .validateAndGetSchedulerConfiguration(mutationInfo, mockHsr);
+    Assert.assertEquals(Status.BAD_REQUEST
+            .getStatusCode(), response.getStatus());
+    Assert.assertTrue(response.getEntity().toString()
+            .contains("Configuration change validation only supported by"
+                    +" MutableConfScheduler."));
+  }
+
+  @Test
+  public void testValidateAndGetSchedulerConfigurationInvalidConfig()
+          throws IOException {
+    Configuration config = CapacitySchedulerConfigGeneratorForTest
+            .createBasicCSConfiguration();
+    ResourceScheduler scheduler = prepareCSForValidation(config);
+
+    SchedConfUpdateInfo mutationInfo = new SchedConfUpdateInfo();
+    ArrayList<String> queuesToRemove = new ArrayList();
+    queuesToRemove.add("root.test1");
+    mutationInfo.setRemoveQueueInfo(queuesToRemove);
+
+    RMWebServices webService = prepareWebServiceForValidation(scheduler);
+    HttpServletRequest mockHsr = prepareServletRequestForValidation();
+
+    Response response = webService
+            .validateAndGetSchedulerConfiguration(mutationInfo, mockHsr);
+    Assert.assertEquals(Status.BAD_REQUEST
+            .getStatusCode(), response.getStatus());
+    Assert.assertTrue(response.getEntity().toString()
+            .contains("Illegal capacity of 0.5 for children of queue"));
+  }
+
+  @Test
+  public void testValidateAndGetSchedulerConfigurationValidScheduler()
+          throws IOException {
+    Configuration config = CapacitySchedulerConfigGeneratorForTest
+            .createBasicCSConfiguration();
+    config.set("yarn.scheduler.capacity.root.test1.state", "STOPPED");
+    config.set("yarn.scheduler.capacity.queue-mappings",
+            "u:test2:test2");
+    ResourceScheduler scheduler = prepareCSForValidation(config);
+
+    SchedConfUpdateInfo mutationInfo = new SchedConfUpdateInfo();
+    ArrayList<String> queuesToRemove = new ArrayList();
+    queuesToRemove.add("root.test1");
+    mutationInfo.setRemoveQueueInfo(queuesToRemove);
+    ArrayList<QueueConfigInfo> updateQueueInfo = new ArrayList<>();
+    String queueToUpdate = "root.test2";
+    Map<String, String> propertiesToUpdate = new HashMap<>();
+    propertiesToUpdate.put("capacity", "100");
+    updateQueueInfo.add(new QueueConfigInfo(queueToUpdate, propertiesToUpdate));
+    mutationInfo.setUpdateQueueInfo(updateQueueInfo);
+
+    RMWebServices webService = prepareWebServiceForValidation(scheduler);
+    HttpServletRequest mockHsr = prepareServletRequestForValidation();
+
+    Response response = webService
+            .validateAndGetSchedulerConfiguration(mutationInfo, mockHsr);
+    Assert.assertEquals(Status.OK
+            .getStatusCode(), response.getStatus());
+  }
+
+  private CapacityScheduler prepareCSForValidation(Configuration config)
+          throws IOException {
+    CapacityScheduler scheduler = mock(CapacityScheduler.class);
+    when(scheduler.isConfigurationMutable())
+            .thenReturn(true);
+    MutableCSConfigurationProvider configurationProvider =
+            mock(MutableCSConfigurationProvider.class);
+    when(scheduler.getMutableConfProvider())
+            .thenReturn(configurationProvider);
+
+    when(configurationProvider.getConfiguration()).thenReturn(config);
+    when(scheduler.getConf()).thenReturn(config);
+    when(configurationProvider
+            .applyChanges(any(), any())).thenCallRealMethod();
+    return scheduler;
+  }
+
+  private HttpServletRequest prepareServletRequestForValidation() {
+    HttpServletRequest mockHsr = mock(HttpServletRequest.class);
+    when(mockHsr.getUserPrincipal()).thenReturn(() -> "yarn");
+    return mockHsr;
+  }
+
+  private RMWebServices prepareWebServiceForValidation(
+          ResourceScheduler scheduler) {
+    ResourceManager mockRM = mock(ResourceManager.class);
+    ApplicationACLsManager acLsManager = mock(ApplicationACLsManager.class);
+    RMWebServices webService = new RMWebServices(mockRM, new Configuration(),
+            mock(HttpServletResponse.class));
+    when(mockRM.getResourceScheduler()).thenReturn(scheduler);
+    when(acLsManager.areACLsEnabled()).thenReturn(false);
+    when(mockRM.getApplicationACLsManager()).thenReturn(acLsManager);
+    RMContext context = TestCapacitySchedulerConfigValidator.prepareRMContext();
+    when(mockRM.getRMContext()).thenReturn(context);
+
+    return  webService;
+  }
+
 }