YARN-3288. Document and fix indentation in the DockerContainerExecutor code

(cherry picked from commit e0ccea33c9)

hadoop-yarn-project/CHANGES.txt

@@ -33,6 +33,8 @@ Release 2.8.0 - UNRELEASED
 
     YARN-3397. yarn rmadmin should skip -failover. (J.Andreina via kasha)
 
+    YARN-3288. Document and fix indentation in the DockerContainerExecutor code
+
   OPTIMIZATIONS
 
     YARN-3339. TestDockerContainerExecutor should pull a single image and not

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/ContainerExecutor.java

@@ -210,8 +210,22 @@ public abstract class ContainerExecutor implements Configurable {
     }
   }
 
-  public void writeLaunchEnv(OutputStream out, Map<String, String> environment, Map<Path, List<String>> resources, List<String> command) throws IOException{
+  /**
-    ContainerLaunch.ShellScriptBuilder sb = ContainerLaunch.ShellScriptBuilder.create();
+   * This method writes out the launch environment of a container. This can be
+   * overridden by extending ContainerExecutors to provide different behaviors
+   * @param out the output stream to which the environment is written (usually
+   * a script file which will be executed by the Launcher)
+   * @param environment The environment variables and their values
+   * @param resources The resources which have been localized for this container
+   * Symlinks will be created to these localized resources
+   * @param command The command that will be run.
+   * @throws IOException if any errors happened writing to the OutputStream,
+   * while creating symlinks
+   */
+  public void writeLaunchEnv(OutputStream out, Map<String, String> environment,
+    Map<Path, List<String>> resources, List<String> command) throws IOException{
+    ContainerLaunch.ShellScriptBuilder sb =
+      ContainerLaunch.ShellScriptBuilder.create();
     if (environment != null) {
       for (Map.Entry<String,String> env : environment.entrySet()) {
         sb.env(env.getKey().toString(), env.getValue().toString());

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/DockerContainerExecutor.java

@@ -18,10 +18,24 @@
 
 package org.apache.hadoop.yarn.server.nodemanager;
 
-import com.google.common.annotations.VisibleForTesting;
+import static org.apache.hadoop.fs.CreateFlag.CREATE;
-import com.google.common.base.Joiner;
+import static org.apache.hadoop.fs.CreateFlag.OVERWRITE;
-import com.google.common.base.Preconditions;
+
-import com.google.common.base.Strings;
+import java.io.ByteArrayOutputStream;
+import java.io.DataOutputStream;
+import java.io.File;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.io.PrintStream;
+import java.net.InetSocketAddress;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.EnumSet;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.regex.Pattern;
 
 import org.apache.commons.lang.math.RandomUtils;
 import org.apache.commons.logging.Log;
@@ -45,38 +59,35 @@ import org.apache.hadoop.yarn.server.nodemanager.containermanager.launcher.Conta
 import org.apache.hadoop.yarn.server.nodemanager.containermanager.localizer.ContainerLocalizer;
 import org.apache.hadoop.yarn.util.ConverterUtils;
 
-import java.io.ByteArrayOutputStream;
+import com.google.common.annotations.VisibleForTesting;
-import java.io.DataOutputStream;
+import com.google.common.base.Joiner;
-import java.io.File;
+import com.google.common.base.Preconditions;
-import java.io.IOException;
+import com.google.common.base.Strings;
-import java.io.OutputStream;
-import java.io.PrintStream;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.EnumSet;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Map;
-import java.util.Random;
-import java.util.Set;
-import java.util.regex.Pattern;
-import java.net.InetSocketAddress;
-import static org.apache.hadoop.fs.CreateFlag.CREATE;
-import static org.apache.hadoop.fs.CreateFlag.OVERWRITE;
 
 /**
- * This executor will launch a docker container and run the task inside the container.
+ * This executor will launch and run tasks inside Docker containers. It
+ * currently only supports simple authentication mode. It shares a lot of code
+ * with the DefaultContainerExecutor (and it may make sense to pull out those
+ * common pieces later).
  */
 public class DockerContainerExecutor extends ContainerExecutor {
-
   private static final Log LOG = LogFactory
     .getLog(DockerContainerExecutor.class);
-  public static final String DOCKER_CONTAINER_EXECUTOR_SCRIPT = "docker_container_executor";
+  //The name of the script file that will launch the Docker containers
-  public static final String DOCKER_CONTAINER_EXECUTOR_SESSION_SCRIPT = "docker_container_executor_session";
+  public static final String DOCKER_CONTAINER_EXECUTOR_SCRIPT =
-
+    "docker_container_executor";
-  // This validates that the image is a proper docker image and would not crash docker.
+  //The name of the session script that the DOCKER_CONTAINER_EXECUTOR_SCRIPT
-  public static final String DOCKER_IMAGE_PATTERN = "^(([\\w\\.-]+)(:\\d+)*\\/)?[\\w\\.:-]+$";
+  //launches in turn
+  public static final String DOCKER_CONTAINER_EXECUTOR_SESSION_SCRIPT =
+    "docker_container_executor_session";
 
+  //This validates that the image is a proper docker image and would not crash
+  //docker. The image name is not allowed to contain spaces. e.g.
+  //registry.somecompany.com:9999/containername:0.1 or
+  //containername:0.1 or
+  //containername
+  public static final String DOCKER_IMAGE_PATTERN =
+    "^(([\\w\\.-]+)(:\\d+)*\\/)?[\\w\\.:-]+$";
 
   private final FileContext lfs;
   private final Pattern dockerImagePattern;
@@ -96,14 +107,18 @@ public class DockerContainerExecutor extends ContainerExecutor {
 
   @Override
   public void init() throws IOException {
-    String auth = getConf().get(CommonConfigurationKeys.HADOOP_SECURITY_AUTHENTICATION);
+    String auth =
+      getConf().get(CommonConfigurationKeys.HADOOP_SECURITY_AUTHENTICATION);
     if (auth != null && !auth.equals("simple")) {
-      throw new IllegalStateException("DockerContainerExecutor only works with simple authentication mode");
+      throw new IllegalStateException(
+        "DockerContainerExecutor only works with simple authentication mode");
     }
-    String dockerExecutor = getConf().get(YarnConfiguration.NM_DOCKER_CONTAINER_EXECUTOR_EXEC_NAME,
+    String dockerExecutor = getConf().get(
+      YarnConfiguration.NM_DOCKER_CONTAINER_EXECUTOR_EXEC_NAME,
       YarnConfiguration.NM_DEFAULT_DOCKER_CONTAINER_EXECUTOR_EXEC_NAME);
     if (!new File(dockerExecutor).exists()) {
-      throw new IllegalStateException("Invalid docker exec path: " + dockerExecutor);
+      throw new IllegalStateException(
+        "Invalid docker exec path: " + dockerExecutor);
     }
   }
 
@@ -112,7 +127,6 @@ public class DockerContainerExecutor extends ContainerExecutor {
     InetSocketAddress nmAddr, String user, String appId, String locId,
     LocalDirsHandlerService dirsHandler)
     throws IOException, InterruptedException {
-
     List<String> localDirs = dirsHandler.getLocalDirs();
     List<String> logDirs = dirsHandler.getLogDirs();
 
@@ -128,7 +142,8 @@ public class DockerContainerExecutor extends ContainerExecutor {
     // randomly choose the local directory
     Path appStorageDir = getWorkingDir(localDirs, user, appId);
 
-    String tokenFn = String.format(ContainerLocalizer.TOKEN_FILE_NAME_FMT, locId);
+    String tokenFn =
+      String.format(ContainerLocalizer.TOKEN_FILE_NAME_FMT, locId);
     Path tokenDst = new Path(appStorageDir, tokenFn);
     copyFile(nmPrivateContainerTokensPath, tokenDst, user);
     LOG.info("Copying from " + nmPrivateContainerTokensPath + " to " + tokenDst);
@@ -140,20 +155,25 @@ public class DockerContainerExecutor extends ContainerExecutor {
 
 
   @Override
-  public int launchContainer(Container container,
+  public int launchContainer(Container container, Path
-                             Path nmPrivateContainerScriptPath, Path nmPrivateTokensPath,
+    nmPrivateContainerScriptPath, Path nmPrivateTokensPath, String userName,
-                             String userName, String appId, Path containerWorkDir,
+    String appId, Path containerWorkDir, List<String> localDirs, List<String>
-                             List<String> localDirs, List<String> logDirs) throws IOException {
+    logDirs) throws IOException {
+    //Variables for the launch environment can be injected from the command-line
+    //while submitting the application
     String containerImageName = container.getLaunchContext().getEnvironment()
       .get(YarnConfiguration.NM_DOCKER_CONTAINER_EXECUTOR_IMAGE_NAME);
     if (LOG.isDebugEnabled()) {
       LOG.debug("containerImageName from launchContext: " + containerImageName);
     }
-    Preconditions.checkArgument(!Strings.isNullOrEmpty(containerImageName), "Container image must not be null");
+    Preconditions.checkArgument(!Strings.isNullOrEmpty(containerImageName),
+      "Container image must not be null");
     containerImageName = containerImageName.replaceAll("['\"]", "");
 
-    Preconditions.checkArgument(saneDockerImage(containerImageName), "Image: " + containerImageName + " is not a proper docker image");
+    Preconditions.checkArgument(saneDockerImage(containerImageName), "Image: "
-    String dockerExecutor = getConf().get(YarnConfiguration.NM_DOCKER_CONTAINER_EXECUTOR_EXEC_NAME,
+      + containerImageName + " is not a proper docker image");
+    String dockerExecutor = getConf().get(
+      YarnConfiguration.NM_DOCKER_CONTAINER_EXECUTOR_EXEC_NAME,
       YarnConfiguration.NM_DEFAULT_DOCKER_CONTAINER_EXECUTOR_EXEC_NAME);
 
     FsPermission dirPerm = new FsPermission(APPDIR_PERM);
@@ -161,10 +181,8 @@ public class DockerContainerExecutor extends ContainerExecutor {
 
     // create container dirs on all disks
     String containerIdStr = ConverterUtils.toString(containerId);
-    String appIdStr =
+    String appIdStr = ConverterUtils.toString(
-        ConverterUtils.toString(
+      containerId.getApplicationAttemptId().getApplicationId());
-            containerId.getApplicationAttemptId().
-                getApplicationId());
     for (String sLocalDir : localDirs) {
       Path usersdir = new Path(sLocalDir, ContainerLocalizer.USERCACHE);
       Path userdir = new Path(usersdir, userName);
@@ -191,12 +209,17 @@ public class DockerContainerExecutor extends ContainerExecutor {
       new Path(containerWorkDir, ContainerLaunch.FINAL_CONTAINER_TOKENS_FILE);
     lfs.util().copy(nmPrivateTokensPath, tokenDst);
 
-
-
     String localDirMount = toMount(localDirs);
     String logDirMount = toMount(logDirs);
-    String containerWorkDirMount = toMount(Collections.singletonList(containerWorkDir.toUri().getPath()));
+    String containerWorkDirMount = toMount(Collections.singletonList(
+      containerWorkDir.toUri().getPath()));
     StringBuilder commands = new StringBuilder();
+    //Use docker run to launch the docker container. See man pages for
+    //docker-run
+    //--rm removes the container automatically once the container finishes
+    //--net=host allows the container to take on the host's network stack
+    //--name sets the Docker Container name to the YARN containerId string
+    //-v is used to bind mount volumes for local, log and work dirs.
     String commandStr = commands.append(dockerExecutor)
       .append(" ")
       .append("run")
@@ -210,14 +233,20 @@ public class DockerContainerExecutor extends ContainerExecutor {
       .append(" ")
       .append(containerImageName)
       .toString();
-    String dockerPidScript = "`" + dockerExecutor + " inspect --format {{.State.Pid}} " + containerIdStr + "`";
+    //Get the pid of the process which has been launched as a docker container
+    //using docker inspect
+    String dockerPidScript = "`" + dockerExecutor +
+      " inspect --format {{.State.Pid}} " + containerIdStr + "`";
+
     // Create new local launch wrapper script
-    LocalWrapperScriptBuilder sb =
+    LocalWrapperScriptBuilder sb = new UnixLocalWrapperScriptBuilder(
-      new UnixLocalWrapperScriptBuilder(containerWorkDir, commandStr, dockerPidScript);
+      containerWorkDir, commandStr, dockerPidScript);
     Path pidFile = getPidFilePath(containerId);
     if (pidFile != null) {
       sb.writeLocalWrapperScript(launchDst, pidFile);
     } else {
+      //Although the container was activated by ContainerLaunch before exec()
+      //was called, since then deactivateContainer() has been called.
       LOG.info("Container " + containerIdStr
           + " was marked as inactive. Returning terminated error");
       return ExitCode.TERMINATED.getExitCode();
@@ -234,7 +263,8 @@ public class DockerContainerExecutor extends ContainerExecutor {
       String[] command = getRunCommand(sb.getWrapperScriptPath().toString(),
         containerIdStr, userName, pidFile, this.getConf());
       if (LOG.isDebugEnabled()) {
-        LOG.debug("launchContainer: " + commandStr + " " + Joiner.on(" ").join(command));
+        LOG.debug("launchContainer: " + commandStr + " " +
+          Joiner.on(" ").join(command));
       }
       shExec = new ShellCommandExecutor(
         command,
@@ -279,9 +309,17 @@ public class DockerContainerExecutor extends ContainerExecutor {
   }
 
   @Override
-  public void writeLaunchEnv(OutputStream out, Map<String, String> environment, Map<Path, List<String>> resources, List<String> command) throws IOException {
+  /**
-    ContainerLaunch.ShellScriptBuilder sb = ContainerLaunch.ShellScriptBuilder.create();
+   * Filter the environment variables that may conflict with the ones set in
+   * the docker image and write them out to an OutputStream.
+   */
+  public void writeLaunchEnv(OutputStream out, Map<String, String> environment,
+    Map<Path, List<String>> resources, List<String> command)
+    throws IOException {
+    ContainerLaunch.ShellScriptBuilder sb =
+      ContainerLaunch.ShellScriptBuilder.create();
 
+    //Remove environments that may conflict with the ones in Docker image.
     Set<String> exclusionSet = new HashSet<String>();
     exclusionSet.add(YarnConfiguration.NM_DOCKER_CONTAINER_EXECUTOR_IMAGE_NAME);
     exclusionSet.add(ApplicationConstants.Environment.HADOOP_YARN_HOME.name());
@@ -427,6 +465,9 @@ public class DockerContainerExecutor extends ContainerExecutor {
     return builder.toString();
   }
 
+  //This class facilitates (only) the creation of platform-specific scripts that
+  //will be used to launch the containers
+  //TODO: This should be re-used from the DefaultContainerExecutor.
   private abstract class LocalWrapperScriptBuilder {
 
     private final Path wrapperScriptPath;
@@ -435,7 +476,8 @@ public class DockerContainerExecutor extends ContainerExecutor {
       return wrapperScriptPath;
     }
 
-    public void writeLocalWrapperScript(Path launchDst, Path pidFile) throws IOException {
+    public void writeLocalWrapperScript(Path launchDst, Path pidFile)
+      throws IOException {
       DataOutputStream out = null;
       PrintStream pout = null;
 
@@ -448,8 +490,8 @@ public class DockerContainerExecutor extends ContainerExecutor {
       }
     }
 
-    protected abstract void writeLocalWrapperScript(Path launchDst, Path pidFile,
+    protected abstract void writeLocalWrapperScript(Path launchDst,
-                                                    PrintStream pout);
+      Path pidFile, PrintStream pout);
 
     protected LocalWrapperScriptBuilder(Path containerWorkDir) {
       this.wrapperScriptPath = new Path(containerWorkDir,
@@ -457,13 +499,15 @@ public class DockerContainerExecutor extends ContainerExecutor {
     }
   }
 
+  //TODO: This class too should be used from DefaultContainerExecutor.
   private final class UnixLocalWrapperScriptBuilder
     extends LocalWrapperScriptBuilder {
     private final Path sessionScriptPath;
     private final String dockerCommand;
     private final String dockerPidScript;
 
-    public UnixLocalWrapperScriptBuilder(Path containerWorkDir, String dockerCommand, String dockerPidScript) {
+    public UnixLocalWrapperScriptBuilder(Path containerWorkDir,
+      String dockerCommand, String dockerPidScript) {
       super(containerWorkDir);
       this.dockerCommand = dockerCommand;
       this.dockerPidScript = dockerPidScript;
@@ -481,7 +525,6 @@ public class DockerContainerExecutor extends ContainerExecutor {
     @Override
     public void writeLocalWrapperScript(Path launchDst, Path pidFile,
       PrintStream pout) {
-
       String exitCodeFile = ContainerLaunch.getExitCodeFile(
         pidFile.toString());
       String tmpFile = exitCodeFile + ".tmp";
@@ -505,7 +548,8 @@ public class DockerContainerExecutor extends ContainerExecutor {
         // hence write pid to tmp file first followed by a mv
         pout.println("#!/usr/bin/env bash");
         pout.println();
-        pout.println("echo "+ dockerPidScript +" > " + pidFile.toString() + ".tmp");
+        pout.println("echo "+ dockerPidScript +" > " + pidFile.toString()
+          + ".tmp");
         pout.println("/bin/mv -f " + pidFile.toString() + ".tmp " + pidFile);
         pout.println(dockerCommand + " bash \"" +
           launchDst.toUri().getPath().toString() + "\"");
@@ -538,7 +582,8 @@ public class DockerContainerExecutor extends ContainerExecutor {
     for (String localDir : localDirs) {
       // create $local.dir/usercache/$user and its immediate parent
       try {
-        createDir(getUserCacheDir(new Path(localDir), user), userperms, true, user);
+        createDir(getUserCacheDir(new Path(localDir), user), userperms, true,
+          user);
       } catch (IOException e) {
         LOG.warn("Unable to create the user directory : " + localDir, e);
         continue;

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/launcher/ContainerLaunch.java

@@ -269,8 +269,8 @@ public class ContainerLaunch implements Callable<Integer> {
           localResources, nmPrivateClasspathJarDir);
 
         // Write out the environment
-        exec.writeLaunchEnv(containerScriptOutStream, environment, localResources,
+        exec.writeLaunchEnv(containerScriptOutStream, environment,
-            launchContext.getCommands());
+          localResources, launchContext.getCommands());
 
         // /////////// End of writing out container-script
 

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/test/java/org/apache/hadoop/yarn/server/nodemanager/TestDockerContainerExecutor.java

@@ -18,7 +18,18 @@
 
 package org.apache.hadoop.yarn.server.nodemanager;
 
-import com.google.common.base.Strings;
+import static org.junit.Assert.assertEquals;
+import static org.mockito.Mockito.RETURNS_DEEP_STUBS;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.util.HashMap;
+import java.util.Map;
+
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.conf.Configuration;
@@ -26,43 +37,24 @@ import org.apache.hadoop.fs.FileContext;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.fs.permission.FsPermission;
 import org.apache.hadoop.util.Shell;
-import org.apache.hadoop.yarn.api.ApplicationConstants;
 import org.apache.hadoop.yarn.api.records.ContainerId;
 import org.apache.hadoop.yarn.api.records.ContainerLaunchContext;
 import org.apache.hadoop.yarn.conf.YarnConfiguration;
 import org.apache.hadoop.yarn.server.nodemanager.containermanager.container.Container;
-import org.apache.hadoop.yarn.util.ConverterUtils;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
 
-import java.io.File;
+import com.google.common.base.Strings;
-import java.io.FileOutputStream;
-import java.io.FileReader;
-import java.io.IOException;
-import java.io.LineNumberReader;
-import java.io.PrintWriter;
-import java.util.ArrayList;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertTrue;
-import static org.junit.Assume.assumeTrue;
-import static org.mockito.Mockito.RETURNS_DEEP_STUBS;
-import static org.mockito.Mockito.mock;
-import static org.mockito.Mockito.when;
 
 /**
- * This is intended to test the DockerContainerExecutor code, but it requires docker
+ * This is intended to test the DockerContainerExecutor code, but it requires
- * to be installed.
+ * docker to be installed.
  * <br><ol>
- * <li>Install docker, and Compile the code with docker-service-url set to the host and port
+ * <li>Install docker, and Compile the code with docker-service-url set to the
- * where docker service is running.
+ * host and port where docker service is running.
  * <br><pre><code>
- * > mvn clean install -Ddocker-service-url=tcp://0.0.0.0:4243
+ * > mvn clean install -Ddocker-service-url=tcp://0.0.0.0:4243 -DskipTests
- *                          -DskipTests
  * </code></pre>
  */
 public class TestDockerContainerExecutor {
@@ -75,14 +67,10 @@ public class TestDockerContainerExecutor {
   private FileContext lfs;
   private String yarnImage;
 
-  private int id = 0;
   private String appSubmitter;
   private String dockerUrl;
   private String testImage = "centos:latest";
   private String dockerExec;
-  private String containerIdStr;
-
-
   private ContainerId getNextContainerId() {
     ContainerId cId = mock(ContainerId.class, RETURNS_DEEP_STUBS);
     String id = "CONTAINER_" + System.currentTimeMillis();
@@ -91,6 +79,8 @@ public class TestDockerContainerExecutor {
   }
 
   @Before
+  //Initialize a new DockerContainerExecutor that will be used to launch mocked
+  //containers.
   public void setup() {
     try {
       lfs = FileContext.getLocalFSFileContext();
@@ -113,8 +103,10 @@ public class TestDockerContainerExecutor {
     }
     dockerUrl = " -H " + dockerUrl;
     dockerExec = "docker " + dockerUrl;
-    conf.set(YarnConfiguration.NM_DOCKER_CONTAINER_EXECUTOR_IMAGE_NAME, yarnImage);
+    conf.set(
-    conf.set(YarnConfiguration.NM_DOCKER_CONTAINER_EXECUTOR_EXEC_NAME, dockerExec);
+      YarnConfiguration.NM_DOCKER_CONTAINER_EXECUTOR_IMAGE_NAME, yarnImage);
+    conf.set(
+      YarnConfiguration.NM_DOCKER_CONTAINER_EXECUTOR_EXEC_NAME, dockerExec);
     exec = new DockerContainerExecutor();
     dirsHandler = new LocalDirsHandlerService();
     dirsHandler.init(conf);
@@ -129,7 +121,6 @@ public class TestDockerContainerExecutor {
 
   private Shell.ShellCommandExecutor shellExec(String command) {
     try {
-
       Shell.ShellCommandExecutor shExec = new Shell.ShellCommandExecutor(
         command.split("\\s+"),
         new File(workDir.toUri().getPath()),
@@ -145,14 +136,24 @@ public class TestDockerContainerExecutor {
     return exec != null;
   }
 
-  private int runAndBlock(ContainerId cId, Map<String, String> launchCtxEnv, String... cmd) throws IOException {
+  /**
+   * Test that a docker container can be launched to run a command
+   * @param cId a fake ContainerID
+   * @param launchCtxEnv
+   * @param cmd the command to launch inside the docker container
+   * @return the exit code of the process used to launch the docker container
+   * @throws IOException
+   */
+  private int runAndBlock(ContainerId cId, Map<String, String> launchCtxEnv,
+    String... cmd) throws IOException {
     String appId = "APP_" + System.currentTimeMillis();
     Container container = mock(Container.class);
     ContainerLaunchContext context = mock(ContainerLaunchContext.class);
 
     when(container.getContainerId()).thenReturn(cId);
     when(container.getLaunchContext()).thenReturn(context);
-    when(cId.getApplicationAttemptId().getApplicationId().toString()).thenReturn(appId);
+    when(cId.getApplicationAttemptId().getApplicationId().toString())
+      .thenReturn(appId);
     when(context.getEnvironment()).thenReturn(launchCtxEnv);
 
     String script = writeScriptFile(launchCtxEnv, cmd);
@@ -168,7 +169,9 @@ public class TestDockerContainerExecutor {
       dirsHandler.getLogDirs());
   }
 
-  private String writeScriptFile(Map<String, String> launchCtxEnv, String... cmd) throws IOException {
+  // Write the script used to launch the docker container in a temp file
+  private String writeScriptFile(Map<String, String> launchCtxEnv,
+    String... cmd) throws IOException {
     File f = File.createTempFile("TestDockerContainerExecutor", ".sh");
     f.deleteOnExit();
     PrintWriter p = new PrintWriter(new FileOutputStream(f));
@@ -193,6 +196,10 @@ public class TestDockerContainerExecutor {
     }
   }
 
+  /**
+   * Test that a touch command can be launched successfully in a docker
+   * container
+   */
   @Test
   public void testLaunchContainer() throws IOException {
     if (!shouldRun()) {
@@ -201,12 +208,13 @@ public class TestDockerContainerExecutor {
     }
 
     Map<String, String> env = new HashMap<String, String>();
-    env.put(YarnConfiguration.NM_DOCKER_CONTAINER_EXECUTOR_IMAGE_NAME, testImage);
+    env.put(YarnConfiguration.NM_DOCKER_CONTAINER_EXECUTOR_IMAGE_NAME,
+      testImage);
     String touchFileName = "touch-file-" + System.currentTimeMillis();
     File touchFile = new File(dirsHandler.getLocalDirs().get(0), touchFileName);
     ContainerId cId = getNextContainerId();
-    int ret = runAndBlock(
+    int ret = runAndBlock(cId, env, "touch", touchFile.getAbsolutePath(), "&&",
-        cId, env, "touch", touchFile.getAbsolutePath(), "&&", "cp", touchFile.getAbsolutePath(), "/");
+      "cp", touchFile.getAbsolutePath(), "/");
 
     assertEquals(0, ret);
   }

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/test/java/org/apache/hadoop/yarn/server/nodemanager/TestDockerContainerExecutorWithMocks.java

@@ -18,7 +18,23 @@
 
 package org.apache.hadoop.yarn.server.nodemanager;
 
-import com.google.common.base.Strings;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assume.assumeTrue;
+import static org.mockito.Mockito.RETURNS_DEEP_STUBS;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import java.io.File;
+import java.io.FileReader;
+import java.io.IOException;
+import java.io.LineNumberReader;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.conf.Configuration;
@@ -36,23 +52,6 @@ import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
 
-import java.io.File;
-import java.io.FileReader;
-import java.io.IOException;
-import java.io.LineNumberReader;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.List;
-
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertTrue;
-import static org.junit.Assume.assumeTrue;
-import static org.mockito.Mockito.mock;
-import static org.mockito.Mockito.when;
-import static org.mockito.Mockito.RETURNS_DEEP_STUBS;
-
 /**
  * Mock tests for docker container executor
  */
@@ -81,8 +80,10 @@ public class TestDockerContainerExecutorWithMocks {
     conf.set(YarnConfiguration.NM_LINUX_CONTAINER_EXECUTOR_PATH, executorPath);
     conf.set(YarnConfiguration.NM_LOCAL_DIRS, "/tmp/nm-local-dir" + time);
     conf.set(YarnConfiguration.NM_LOG_DIRS, "/tmp/userlogs" + time);
-    conf.set(YarnConfiguration.NM_DOCKER_CONTAINER_EXECUTOR_IMAGE_NAME, yarnImage);
+    conf.set(YarnConfiguration.NM_DOCKER_CONTAINER_EXECUTOR_IMAGE_NAME,
-    conf.set(YarnConfiguration.NM_DOCKER_CONTAINER_EXECUTOR_EXEC_NAME , DOCKER_LAUNCH_COMMAND);
+      yarnImage);
+    conf.set(YarnConfiguration.NM_DOCKER_CONTAINER_EXECUTOR_EXEC_NAME,
+      DOCKER_LAUNCH_COMMAND);
     dockerContainerExecutor = new DockerContainerExecutor();
     dirsHandler = new LocalDirsHandlerService();
     dirsHandler.init(conf);
@@ -95,7 +96,6 @@ public class TestDockerContainerExecutorWithMocks {
     } catch (IOException e) {
       throw new RuntimeException(e);
     }
-
   }
 
   @After
@@ -110,6 +110,8 @@ public class TestDockerContainerExecutorWithMocks {
   }
 
   @Test(expected = IllegalStateException.class)
+  //Test that DockerContainerExecutor doesn't successfully init on a secure
+  //cluster
   public void testContainerInitSecure() throws IOException {
     dockerContainerExecutor.getConf().set(
       CommonConfigurationKeys.HADOOP_SECURITY_AUTHENTICATION, "kerberos");
@@ -117,6 +119,8 @@ public class TestDockerContainerExecutorWithMocks {
   }
 
   @Test(expected = IllegalArgumentException.class)
+  //Test that when the image name is null, the container launch throws an
+  //IllegalArgumentException
   public void testContainerLaunchNullImage() throws IOException {
     String appSubmitter = "nobody";
     String appId = "APP_ID";
@@ -126,17 +130,19 @@ public class TestDockerContainerExecutorWithMocks {
     Container container = mock(Container.class, RETURNS_DEEP_STUBS);
     ContainerId cId = mock(ContainerId.class, RETURNS_DEEP_STUBS);
     ContainerLaunchContext context = mock(ContainerLaunchContext.class);
-    HashMap<String, String> env = new HashMap<String,String>();
 
+    HashMap<String, String> env = new HashMap<String,String>();
     when(container.getContainerId()).thenReturn(cId);
     when(container.getLaunchContext()).thenReturn(context);
-    when(cId.getApplicationAttemptId().getApplicationId().toString()).thenReturn(appId);
+    when(cId.getApplicationAttemptId().getApplicationId().toString())
+      .thenReturn(appId);
     when(cId.toString()).thenReturn(containerId);
 
     when(context.getEnvironment()).thenReturn(env);
-    env.put(YarnConfiguration.NM_DOCKER_CONTAINER_EXECUTOR_IMAGE_NAME, testImage);
+    env.put(
-    dockerContainerExecutor.getConf()
+      YarnConfiguration.NM_DOCKER_CONTAINER_EXECUTOR_IMAGE_NAME, testImage);
-        .set(YarnConfiguration.NM_DOCKER_CONTAINER_EXECUTOR_IMAGE_NAME, testImage);
+    dockerContainerExecutor.getConf().set(
+      YarnConfiguration.NM_DOCKER_CONTAINER_EXECUTOR_IMAGE_NAME, testImage);
     Path scriptPath = new Path("file:///bin/echo");
     Path tokensPath = new Path("file:///dev/null");
 
@@ -149,6 +155,8 @@ public class TestDockerContainerExecutorWithMocks {
   }
 
   @Test(expected = IllegalArgumentException.class)
+  //Test that when the image name is invalid, the container launch throws an
+  //IllegalArgumentException
   public void testContainerLaunchInvalidImage() throws IOException {
     String appSubmitter = "nobody";
     String appId = "APP_ID";
@@ -162,13 +170,15 @@ public class TestDockerContainerExecutorWithMocks {
 
     when(container.getContainerId()).thenReturn(cId);
     when(container.getLaunchContext()).thenReturn(context);
-    when(cId.getApplicationAttemptId().getApplicationId().toString()).thenReturn(appId);
+    when(cId.getApplicationAttemptId().getApplicationId().toString())
+      .thenReturn(appId);
     when(cId.toString()).thenReturn(containerId);
 
     when(context.getEnvironment()).thenReturn(env);
-    env.put(YarnConfiguration.NM_DOCKER_CONTAINER_EXECUTOR_IMAGE_NAME, testImage);
+    env.put(
-    dockerContainerExecutor.getConf()
+      YarnConfiguration.NM_DOCKER_CONTAINER_EXECUTOR_IMAGE_NAME, testImage);
-      .set(YarnConfiguration.NM_DOCKER_CONTAINER_EXECUTOR_IMAGE_NAME, testImage);
+    dockerContainerExecutor.getConf().set(
+      YarnConfiguration.NM_DOCKER_CONTAINER_EXECUTOR_IMAGE_NAME, testImage);
     Path scriptPath = new Path("file:///bin/echo");
     Path tokensPath = new Path("file:///dev/null");
 
@@ -181,6 +191,8 @@ public class TestDockerContainerExecutorWithMocks {
   }
 
   @Test
+  //Test that a container launch correctly wrote the session script with the
+  //commands we expected
   public void testContainerLaunch() throws IOException {
     String appSubmitter = "nobody";
     String appId = "APP_ID";
@@ -194,40 +206,48 @@ public class TestDockerContainerExecutorWithMocks {
 
     when(container.getContainerId()).thenReturn(cId);
     when(container.getLaunchContext()).thenReturn(context);
-    when(cId.getApplicationAttemptId().getApplicationId().toString()).thenReturn(appId);
+    when(cId.getApplicationAttemptId().getApplicationId().toString())
+      .thenReturn(appId);
     when(cId.toString()).thenReturn(containerId);
 
     when(context.getEnvironment()).thenReturn(env);
-    env.put(YarnConfiguration.NM_DOCKER_CONTAINER_EXECUTOR_IMAGE_NAME, testImage);
+    env.put(
+      YarnConfiguration.NM_DOCKER_CONTAINER_EXECUTOR_IMAGE_NAME, testImage);
     Path scriptPath = new Path("file:///bin/echo");
     Path tokensPath = new Path("file:///dev/null");
 
     Path pidFile = new Path(workDir, "pid");
 
     dockerContainerExecutor.activateContainer(cId, pidFile);
-    int ret = dockerContainerExecutor.launchContainer(container, scriptPath, tokensPath,
+    int ret = dockerContainerExecutor.launchContainer(container, scriptPath,
-        appSubmitter, appId, workDir, dirsHandler.getLocalDirs(),
+      tokensPath, appSubmitter, appId, workDir, dirsHandler.getLocalDirs(),
       dirsHandler.getLogDirs());
     assertEquals(0, ret);
     //get the script
     Path sessionScriptPath = new Path(workDir,
       Shell.appendScriptExtension(
         DockerContainerExecutor.DOCKER_CONTAINER_EXECUTOR_SESSION_SCRIPT));
-    LineNumberReader lnr = new LineNumberReader(new FileReader(sessionScriptPath.toString()));
+    LineNumberReader lnr = new LineNumberReader(new FileReader(
+      sessionScriptPath.toString()));
     boolean cmdFound = false;
     List<String> localDirs = dirsToMount(dirsHandler.getLocalDirs());
     List<String> logDirs = dirsToMount(dirsHandler.getLogDirs());
-    List<String> workDirMount = dirsToMount(Collections.singletonList(workDir.toUri().getPath()));
+    List<String> workDirMount = dirsToMount(Collections.singletonList(
-    List<String> expectedCommands =  new ArrayList<String>(
+      workDir.toUri().getPath()));
-        Arrays.asList(DOCKER_LAUNCH_COMMAND, "run", "--rm", "--net=host",  "--name", containerId));
+    List<String> expectedCommands =  new ArrayList<String>(Arrays.asList(
+      DOCKER_LAUNCH_COMMAND, "run", "--rm", "--net=host",  "--name",
+      containerId));
     expectedCommands.addAll(localDirs);
     expectedCommands.addAll(logDirs);
     expectedCommands.addAll(workDirMount);
     String shellScript =  workDir + "/launch_container.sh";
 
-    expectedCommands.addAll(Arrays.asList(testImage.replaceAll("['\"]", ""), "bash","\"" + shellScript + "\""));
+    expectedCommands.addAll(Arrays.asList(testImage.replaceAll("['\"]", ""),
+      "bash","\"" + shellScript + "\""));
 
-    String expectedPidString = "echo `/bin/true inspect --format {{.State.Pid}} " + containerId+"` > "+ pidFile.toString() + ".tmp";
+    String expectedPidString =
+      "echo `/bin/true inspect --format {{.State.Pid}} " + containerId+"` > "+
+      pidFile.toString() + ".tmp";
     boolean pidSetterFound = false;
     while(lnr.ready()){
       String line = lnr.readLine();