YARN-1611. Introduced the concept of a configuration provider which can be used by ResourceManager to read configuration locally or from remote systems so as to help RM failover. Contributed by Xuan Gong.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1564002 13f79535-47bb-0310-9956-ffa450edef68

hadoop-yarn-project/CHANGES.txt

@@ -82,6 +82,10 @@ Release 2.4.0 - UNRELEASED
     YARN-1633. Defined user-facing entity, entity-info and event objects related
     to Application Timeline feature. (Zhijie Shen via vinodkv)
 
+    YARN-1611. Introduced the concept of a configuration provider which can be
+    used by ResourceManager to read configuration locally or from remote systems
+    so as to help RM failover. (Xuan Gong via vinodkv)
+
   IMPROVEMENTS
 
     YARN-1007. Enhance History Reader interface for Containers. (Mayank Bansal via

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/main/java/org/apache/hadoop/yarn/conf/ConfigurationProvider.java

@@ -0,0 +1,64 @@
+/**
+ * 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.conf;
+
+import java.io.IOException;
+
+import org.apache.hadoop.classification.InterfaceAudience.Private;
+import org.apache.hadoop.classification.InterfaceStability.Unstable;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.yarn.exceptions.YarnException;
+
+@Private
+@Unstable
+/**
+ * Base class to implement ConfigurationProvider.
+ * Real ConfigurationProvider implementations need to derive from it and
+ * implement load methods to actually load the configuration.
+ */
+public abstract class ConfigurationProvider {
+
+  public void init(Configuration conf) throws Exception {
+    initInternal(conf);
+  }
+
+  public void close() throws Exception {
+    closeInternal();
+  }
+
+  /**
+   * Get the configuration.
+   * @param name The configuration file name
+   * @return configuration
+   * @throws YarnException
+   * @throws IOException
+   */
+  public abstract Configuration getConfiguration(String name)
+      throws YarnException, IOException;
+
+  /**
+   * Derived classes initialize themselves using this method.
+   */
+  public abstract void initInternal(Configuration conf) throws Exception;
+
+  /**
+   * Derived classes close themselves using this method.
+   */
+  public abstract void closeInternal() throws Exception;
+}

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/main/java/org/apache/hadoop/yarn/conf/ConfigurationProviderFactory.java

@@ -0,0 +1,57 @@
+/**
+ * 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.conf;
+
+import org.apache.hadoop.classification.InterfaceAudience.Private;
+import org.apache.hadoop.classification.InterfaceStability.Unstable;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.util.ReflectionUtils;
+import org.apache.hadoop.yarn.exceptions.YarnRuntimeException;
+
+@Private
+@Unstable
+/**
+ * Factory for {@link ConfigurationProvider} implementations.
+ */
+public class ConfigurationProviderFactory {
+  /**
+   * Creates an instance of {@link ConfigurationProvider} using given
+   * configuration.
+   * @param conf
+   * @return configurationProvider
+   */
+  @SuppressWarnings("unchecked")
+  public static ConfigurationProvider
+      getConfigurationProvider(Configuration conf) {
+    Class<? extends ConfigurationProvider> defaultProviderClass;
+    try {
+      defaultProviderClass = (Class<? extends ConfigurationProvider>)
+          Class.forName(
+              YarnConfiguration.DEFAULT_RM_CONFIGURATION_PROVIDER_CLASS);
+    } catch (Exception e) {
+      throw new YarnRuntimeException(
+          "Invalid default configuration provider class"
+              + YarnConfiguration.DEFAULT_RM_CONFIGURATION_PROVIDER_CLASS, e);
+    }
+    ConfigurationProvider configurationProvider = ReflectionUtils.newInstance(
+        conf.getClass(YarnConfiguration.RM_CONFIGURATION_PROVIDER_CLASS,
+            defaultProviderClass, ConfigurationProvider.class), conf);
+    return configurationProvider;
+  }
+}

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/main/java/org/apache/hadoop/yarn/conf/YarnConfiguration.java

@@ -37,6 +37,9 @@ import org.apache.hadoop.yarn.api.ApplicationConstants;
 @Evolving
 public class YarnConfiguration extends Configuration {
 
+  @Private
+  public static final String CS_CONFIGURATION_FILE= "capacity-scheduler.xml";
+
   private static final String YARN_DEFAULT_XML_FILE = "yarn-default.xml";
   private static final String YARN_SITE_XML_FILE = "yarn-site.xml";
 
@@ -329,6 +332,16 @@ public class YarnConfiguration extends Configuration {
   public static final String RM_HA_IDS = RM_HA_PREFIX + "rm-ids";
   public static final String RM_HA_ID = RM_HA_PREFIX + "id";
 
+  /** Store the related configuration files in File System */
+  public static final String FS_BASED_RM_CONF_STORE = RM_PREFIX
+      + "configuration.file-system-based-store";
+  public static final String DEFAULT_FS_BASED_RM_CONF_STORE = "/yarn/conf";
+
+  public static final String RM_CONFIGURATION_PROVIDER_CLASS = RM_PREFIX
+      + "configuration.provider-class";
+  public static final String DEFAULT_RM_CONFIGURATION_PROVIDER_CLASS =
+      "org.apache.hadoop.yarn.LocalConfigurationProvider";
+
   @Private
   public static final List<String> RM_SERVICES_ADDRESS_CONF_KEYS =
       Collections.unmodifiableList(Arrays.asList(

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/FileSystemBasedConfigurationProvider.java

@@ -0,0 +1,72 @@
+/**
+ * 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;
+
+import java.io.IOException;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.hadoop.classification.InterfaceAudience.Private;
+import org.apache.hadoop.classification.InterfaceStability.Unstable;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.yarn.conf.ConfigurationProvider;
+import org.apache.hadoop.yarn.conf.YarnConfiguration;
+import org.apache.hadoop.yarn.exceptions.YarnException;
+
+@Private
+@Unstable
+public class FileSystemBasedConfigurationProvider
+    extends ConfigurationProvider {
+
+  private static final Log LOG = LogFactory
+      .getLog(FileSystemBasedConfigurationProvider.class);
+  private FileSystem fs;
+  private Path configDir;
+
+  @Override
+  public synchronized Configuration getConfiguration(String name)
+      throws IOException, YarnException {
+    Path configPath = new Path(this.configDir, name);
+    if (!fs.exists(configPath)) {
+      throw new YarnException("Can not find Configuration: " + name + " in "
+          + configDir);
+    }
+    Configuration conf = new Configuration(false);
+    conf.addResource(fs.open(configPath));
+    return conf;
+  }
+
+  @Override
+  public synchronized void initInternal(Configuration conf) throws Exception {
+    configDir =
+        new Path(conf.get(YarnConfiguration.FS_BASED_RM_CONF_STORE,
+            YarnConfiguration.DEFAULT_FS_BASED_RM_CONF_STORE));
+    fs = configDir.getFileSystem(conf);
+    if (!fs.exists(configDir)) {
+      fs.mkdirs(configDir);
+    }
+  }
+
+  @Override
+  public synchronized void closeInternal() throws Exception {
+    fs.close();
+  }
+}

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/LocalConfigurationProvider.java

@@ -0,0 +1,48 @@
+/**
+ * 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;
+
+import java.io.IOException;
+
+import org.apache.hadoop.classification.InterfaceAudience.Private;
+import org.apache.hadoop.classification.InterfaceStability.Unstable;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.yarn.conf.ConfigurationProvider;
+import org.apache.hadoop.yarn.exceptions.YarnException;
+
+@Private
+@Unstable
+public class LocalConfigurationProvider extends ConfigurationProvider {
+
+  @Override
+  public Configuration getConfiguration(String name)
+      throws IOException, YarnException {
+    return new Configuration();
+  }
+
+  @Override
+  public void initInternal(Configuration conf) throws Exception {
+    // Do nothing
+  }
+
+  @Override
+  public void closeInternal() throws Exception {
+    // Do nothing
+  }
+}

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/resources/yarn-default.xml

@@ -588,6 +588,18 @@
     <value>org.apache.hadoop.yarn.server.applicationhistoryservice.NullApplicationHistoryStore</value>
   </property>
 
+  <property>
+    <description>The class to use as the configuration provider.
+    If org.apache.hadoop.yarn.LocalConfigurationProvider is used,
+    the local configuration will be loaded.
+    If org.apache.hadoop.yarn.FileSystemBasedConfigurationProvider is used,
+    the configuration which will be loaded should be uploaded to remote File system first.
+    </description>>
+    <name>yarn.resourcemanager.configuration.provider-class</name>
+    <value>org.apache.hadoop.yarn.LocalConfigurationProvider</value>
+    <!-- <value>org.apache.hadoop.yarn.FileSystemBasedConfigurationProvider</value> -->
+  </property>
+
   <!-- Node Manager Configs -->
   <property>
     <description>The hostname of the NM.</description>

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

@@ -47,6 +47,8 @@ import org.apache.hadoop.security.authorize.ProxyUsers;
 import org.apache.hadoop.service.CompositeService;
 import org.apache.hadoop.yarn.api.records.NodeId;
 import org.apache.hadoop.yarn.api.records.ResourceOption;
+import org.apache.hadoop.yarn.conf.ConfigurationProvider;
+import org.apache.hadoop.yarn.conf.ConfigurationProviderFactory;
 import org.apache.hadoop.yarn.conf.HAUtil;
 import org.apache.hadoop.yarn.conf.YarnConfiguration;
 import org.apache.hadoop.yarn.exceptions.YarnException;
@@ -89,6 +91,8 @@ public class AdminService extends CompositeService implements
   private InetSocketAddress masterServiceAddress;
   private AccessControlList adminAcl;
   
+  private ConfigurationProvider configurationProvider = null;
+
   private final RecordFactory recordFactory = 
     RecordFactoryProvider.getRecordFactory(null);
 
@@ -109,6 +113,10 @@ public class AdminService extends CompositeService implements
       }
     }
 
+    this.configurationProvider =
+        ConfigurationProviderFactory.getConfigurationProvider(conf);
+    configurationProvider.init(conf);
+
     masterServiceAddress = conf.getSocketAddr(
         YarnConfiguration.RM_ADMIN_ADDRESS,
         YarnConfiguration.DEFAULT_RM_ADMIN_ADDRESS,
@@ -129,6 +137,9 @@ public class AdminService extends CompositeService implements
   @Override
   protected synchronized void serviceStop() throws Exception {
     stopServer();
+    if (this.configurationProvider != null) {
+      configurationProvider.close();
+    }
     super.serviceStop();
   }
 
@@ -295,23 +306,28 @@ public class AdminService extends CompositeService implements
   @Override
   public RefreshQueuesResponse refreshQueues(RefreshQueuesRequest request)
       throws YarnException, StandbyException {
-    UserGroupInformation user = checkAcls("refreshQueues");
+    String argName = "refreshQueues";
+    UserGroupInformation user = checkAcls(argName);
 
     if (!isRMActive()) {
-      RMAuditLogger.logFailure(user.getShortUserName(), "refreshQueues",
+      RMAuditLogger.logFailure(user.getShortUserName(), argName,
           adminAcl.toString(), "AdminService",
           "ResourceManager is not active. Can not refresh queues.");
       throwStandbyException();
     }
 
+    RefreshQueuesResponse response =
+        recordFactory.newRecordInstance(RefreshQueuesResponse.class);
     try {
-      rmContext.getScheduler().reinitialize(getConfig(), this.rmContext);
+      Configuration conf =
-      RMAuditLogger.logSuccess(user.getShortUserName(), "refreshQueues", 
+          getConfiguration(YarnConfiguration.CS_CONFIGURATION_FILE);
+      rmContext.getScheduler().reinitialize(conf, this.rmContext);
+      RMAuditLogger.logSuccess(user.getShortUserName(), argName,
           "AdminService");
-      return recordFactory.newRecordInstance(RefreshQueuesResponse.class);
+      return response;
     } catch (IOException ioe) {
       LOG.info("Exception refreshing queues ", ioe);
-      RMAuditLogger.logFailure(user.getShortUserName(), "refreshQueues",
+      RMAuditLogger.logFailure(user.getShortUserName(), argName,
           adminAcl.toString(), "AdminService",
           "Exception refreshing queues");
       throw RPCUtil.getRemoteException(ioe);
@@ -484,4 +500,8 @@ public class AdminService extends CompositeService implements
       return response;
   }
 
+  private synchronized Configuration getConfiguration(String confFileName)
+      throws YarnException, IOException {
+    return this.configurationProvider.getConfiguration(confFileName);
+  }
 }

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

@@ -195,6 +195,7 @@ public class CapacityScheduler extends AbstractYarnScheduler
 
   private ResourceCalculator calculator;
   private boolean usePortForNodeName;
+  private boolean useLocalConfigurationProvider;
 
   public CapacityScheduler() {}
 
@@ -261,7 +262,13 @@ public class CapacityScheduler extends AbstractYarnScheduler
   public synchronized void
       reinitialize(Configuration conf, RMContext rmContext) throws IOException {
     if (!initialized) {
-      this.conf = new CapacitySchedulerConfiguration(conf);
+      this.useLocalConfigurationProvider = conf.get(
+          YarnConfiguration.RM_CONFIGURATION_PROVIDER_CLASS,
+          YarnConfiguration.DEFAULT_RM_CONFIGURATION_PROVIDER_CLASS).equals(
+          "org.apache.hadoop.yarn.LocalConfigurationProvider");
+      this.conf =
+          new CapacitySchedulerConfiguration(conf,
+              this.useLocalConfigurationProvider);
       validateConf(this.conf);
       this.minimumAllocation = this.conf.getMinimumAllocation();
       this.maximumAllocation = this.conf.getMaximumAllocation();
@@ -279,9 +286,10 @@ public class CapacityScheduler extends AbstractYarnScheduler
           "minimumAllocation=<" + getMinimumResourceCapability() + ">, " +
           "maximumAllocation=<" + getMaximumResourceCapability() + ">");
     } else {
-
       CapacitySchedulerConfiguration oldConf = this.conf; 
-      this.conf = new CapacitySchedulerConfiguration(conf);
+      this.conf =
+          new CapacitySchedulerConfiguration(conf,
+              this.useLocalConfigurationProvider);
       validateConf(this.conf);
       try {
         LOG.info("Re-initializing queues...");

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

@@ -140,8 +140,15 @@ public class CapacitySchedulerConfiguration extends Configuration {
   }
   
   public CapacitySchedulerConfiguration(Configuration configuration) {
+    this(configuration, true);
+  }
+
+  public CapacitySchedulerConfiguration(Configuration configuration,
+      boolean useLocalConfigurationProvider) {
     super(configuration);
-    addResource(CS_CONFIGURATION_FILE);
+    if (useLocalConfigurationProvider) {
+      addResource(CS_CONFIGURATION_FILE);
+    }
   }
 
   private String getQueuePrefix(String queue) {

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

@@ -0,0 +1,171 @@
+/**
+ * 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;
+
+import static org.junit.Assert.fail;
+
+import java.io.DataOutputStream;
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FileStatus;
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.yarn.conf.YarnConfiguration;
+import org.apache.hadoop.yarn.exceptions.YarnException;
+import org.apache.hadoop.yarn.server.api.protocolrecords.RefreshQueuesRequest;
+import org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler;
+import org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacitySchedulerConfiguration;
+import org.junit.After;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+
+public class TestRMAdminService {
+
+  private final Configuration configuration = new YarnConfiguration();
+  private MockRM rm = null;
+  private FileSystem fs;
+  private Path workingPath;
+  private Path tmpDir;
+
+  @Before
+  public void setup() throws IOException {
+    fs = FileSystem.get(configuration);
+    workingPath =
+        new Path(new File("target", this.getClass().getSimpleName()
+            + "-remoteDir").getAbsolutePath());
+    configuration.set(YarnConfiguration.FS_BASED_RM_CONF_STORE,
+        workingPath.toString());
+    tmpDir = new Path(new File("target", this.getClass().getSimpleName()
+        + "-tmpDir").getAbsolutePath());
+    fs.delete(workingPath, true);
+    fs.delete(tmpDir, true);
+    fs.mkdirs(workingPath);
+    fs.mkdirs(tmpDir);
+  }
+
+  @After
+  public void tearDown() throws IOException {
+    if (rm != null) {
+      rm.stop();
+    }
+    fs.delete(workingPath, true);
+    fs.delete(tmpDir, true);
+  }
+  @Test
+  public void testAdminRefreshQueuesWithLocalConfigurationProvider()
+      throws IOException, YarnException {
+    rm = new MockRM(configuration);
+    rm.init(configuration);
+    rm.start();
+
+    CapacityScheduler cs =
+        (CapacityScheduler) rm.getRMContext().getScheduler();
+    int maxAppsBefore = cs.getConfiguration().getMaximumSystemApplications();
+
+    try {
+      rm.adminService.refreshQueues(RefreshQueuesRequest.newInstance());
+      Assert.assertEquals(maxAppsBefore, cs.getConfiguration()
+          .getMaximumSystemApplications());
+    } catch (Exception ex) {
+      fail("Using localConfigurationProvider. Should not get any exception.");
+    }
+  }
+
+  @Test
+  public void testAdminRefreshQueuesWithFileSystemBasedConfigurationProvider()
+      throws IOException, YarnException {
+    Configuration.addDefaultResource(YarnConfiguration.CS_CONFIGURATION_FILE);
+    configuration.set(YarnConfiguration.RM_CONFIGURATION_PROVIDER_CLASS,
+        "org.apache.hadoop.yarn.FileSystemBasedConfigurationProvider");
+    rm = new MockRM(configuration);
+    rm.init(configuration);
+    rm.start();
+
+    // clean the remoteDirectory
+    cleanRemoteDirectory();
+
+    CapacityScheduler cs =
+        (CapacityScheduler) rm.getRMContext().getScheduler();
+    int maxAppsBefore = cs.getConfiguration().getMaximumSystemApplications();
+
+    try {
+      rm.adminService.refreshQueues(RefreshQueuesRequest.newInstance());
+      fail("FileSystemBasedConfigurationProvider is used." +
+          " Should get an exception here");
+    } catch (Exception ex) {
+      Assert.assertTrue(ex.getMessage().contains(
+          "Can not find Configuration: capacity-scheduler.xml"));
+    }
+
+    CapacitySchedulerConfiguration csConf =
+        new CapacitySchedulerConfiguration();
+    csConf.set("yarn.scheduler.capacity.maximum-applications", "5000");
+    String csConfFile = writeConfigurationXML(csConf,
+        "capacity-scheduler.xml");
+
+    // upload the file into Remote File System
+    uploadToRemoteFileSystem(new Path(csConfFile));
+
+    rm.adminService.refreshQueues(RefreshQueuesRequest.newInstance());
+
+    int maxAppsAfter = cs.getConfiguration().getMaximumSystemApplications();
+    Assert.assertEquals(maxAppsAfter, 5000);
+    Assert.assertTrue(maxAppsAfter != maxAppsBefore);
+  }
+
+  private String writeConfigurationXML(Configuration conf, String confXMLName)
+      throws IOException {
+    DataOutputStream output = null;
+    try {
+      final File confFile = new File(tmpDir.toString(), confXMLName);
+      if (confFile.exists()) {
+        confFile.delete();
+      }
+      if (!confFile.createNewFile()) {
+        Assert.fail("Can not create " + confXMLName);
+      }
+      output = new DataOutputStream(
+          new FileOutputStream(confFile));
+      conf.writeXml(output);
+      return confFile.getAbsolutePath();
+    } finally {
+      if (output != null) {
+        output.close();
+      }
+    }
+  }
+
+  private void uploadToRemoteFileSystem(Path filePath)
+      throws IOException {
+    fs.copyFromLocalFile(filePath, workingPath);
+  }
+
+  private void cleanRemoteDirectory() throws IOException {
+    if (fs.exists(workingPath)) {
+      for (FileStatus file : fs.listStatus(workingPath)) {
+        fs.delete(file.getPath(), true);
+      }
+    }
+  }
+}