YARN-6968. Hardcoded absolute pathname in DockerLinuxContainerRuntime. Contributed by Eric Badger

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/linux/resources/CGroupsHandler.java

@@ -173,4 +173,10 @@ void updateCGroupParam(CGroupController controller, String cGroupId,
    */
   String getCGroupParam(CGroupController controller, String cGroupId,
       String param) throws ResourceHandlerException;
+
+  /**
+   * Returns CGroup Mount Path.
+   * @return parameter value as read from the parameter file
+   */
+  String getCGroupMountPath();
 }

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/linux/resources/CGroupsHandlerImpl.java

@@ -603,4 +603,9 @@ public String getCGroupParam(CGroupController controller, String cGroupId,
           "Unable to read from " + cGroupParamPath);
     }
   }
+
+  @Override
+  public String getCGroupMountPath() {
+    return cGroupMountPath;
+  }
 }

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/linux/runtime/DockerLinuxContainerRuntime.java

@@ -167,13 +167,12 @@ public class DockerLinuxContainerRuntime implements LinuxContainerRuntime {
   public static final String ENV_DOCKER_CONTAINER_LOCAL_RESOURCE_MOUNTS =
       "YARN_CONTAINER_RUNTIME_DOCKER_LOCAL_RESOURCE_MOUNTS";
 
-  static final String CGROUPS_ROOT_DIRECTORY = "/sys/fs/cgroup";
-
   private Configuration conf;
   private DockerClient dockerClient;
   private PrivilegedOperationExecutor privilegedOperationExecutor;
   private Set<String> allowedNetworks = new HashSet<>();
   private String defaultNetwork;
+  private String cgroupsRootDirectory;
   private CGroupsHandler cGroupsHandler;
   private AccessControlList privilegedContainersAcl;
 
@@ -228,6 +227,7 @@ public DockerLinuxContainerRuntime(PrivilegedOperationExecutor
       LOG.info("cGroupsHandler is null - cgroups not in use.");
     } else {
       this.cGroupsHandler = cGroupsHandler;
+      this.cgroupsRootDirectory = cGroupsHandler.getCGroupMountPath();
     }
   }
 
@@ -486,9 +486,12 @@ public void launchContainer(ContainerRuntimeContext ctx)
         .setContainerWorkDir(containerWorkDir.toString())
         .setNetworkType(network);
     setHostname(runCommand, containerIdStr, hostname);
-    runCommand.setCapabilities(capabilities)
+    runCommand.setCapabilities(capabilities);
-        .addMountLocation(CGROUPS_ROOT_DIRECTORY,
+
-            CGROUPS_ROOT_DIRECTORY + ":ro", false);
+    if(cgroupsRootDirectory != null) {
+      runCommand.addMountLocation(cgroupsRootDirectory,
+          cgroupsRootDirectory + ":ro", false);
+    }
 
     List<String> allDirs = new ArrayList<>(containerLocalDirs);
     allDirs.addAll(filecacheDirs);

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/test/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/linux/runtime/TestDockerContainerRuntime.java

@@ -33,6 +33,7 @@
 import org.apache.hadoop.yarn.server.nodemanager.containermanager.linux.privileged.PrivilegedOperationException;
 import org.apache.hadoop.yarn.server.nodemanager.containermanager.linux.privileged.PrivilegedOperationExecutor;
 import org.apache.hadoop.yarn.server.nodemanager.containermanager.linux.resources.CGroupsHandler;
+import org.apache.hadoop.yarn.server.nodemanager.containermanager.linux.resources.ResourceHandlerModule;
 import org.apache.hadoop.yarn.server.nodemanager.containermanager.linux.runtime.docker.DockerRunCommand;
 import org.apache.hadoop.yarn.server.nodemanager.containermanager.runtime.ContainerExecutionException;
 import org.apache.hadoop.yarn.server.nodemanager.containermanager.runtime.ContainerRuntimeConstants;
@@ -261,12 +262,18 @@ private String getExpectedTestCapabilitiesArgumentString()  {
   }
 
   private String getExpectedCGroupsMountString() {
+    CGroupsHandler cgroupsHandler = ResourceHandlerModule.getCGroupsHandler();
+    if(cgroupsHandler == null) {
+      return "";
+    }
+
+    String cgroupMountPath = cgroupsHandler.getCGroupMountPath();
     boolean cGroupsMountExists = new File(
-        DockerLinuxContainerRuntime.CGROUPS_ROOT_DIRECTORY).exists();
+        cgroupMountPath).exists();
 
     if(cGroupsMountExists) {
-      return "-v " + DockerLinuxContainerRuntime.CGROUPS_ROOT_DIRECTORY
+      return "-v " + cgroupMountPath
-          + ":" + DockerLinuxContainerRuntime.CGROUPS_ROOT_DIRECTORY + ":ro ";
+          + ":" + cgroupMountPath + ":ro ";
     } else {
       return "";
     }