Package org.apache.hadoop.security

Class Groups

java.lang.Object
org.apache.hadoop.security.Groups
@LimitedPrivate({"HDFS","MapReduce"}) @Evolving public class Groups extends Object
A user-to-groups mapping service. Groups allows for server to get the various group memberships of a given user via the getGroups(String) call, thus ensuring a consistent user-to-groups mapping and protects against vagaries of different mappings on servers and clients in a Hadoop cluster.

  • Constructor Details

  • Method Details

    • getGroups

      @Deprecated public List<String> getGroups(String user) throws IOException
      Deprecated.
      Use getGroupsSet(String user) instead.
      Get the group memberships of a given user. If the user's group is not cached, this method may block. Note this method can be expensive as it involves Set -> List conversion. For user with large group membership (i.e., > 1000 groups), we recommend using getGroupSet to avoid the conversion and fast membership look up via contains().
      Parameters:
      user - User's name
      Returns:
      the group memberships of the user as list
      Throws:
      IOException - if user does not exist

    • getGroupsSet

      public Set<String> getGroupsSet(String user) throws IOException
      Get the group memberships of a given user. If the user's group is not cached, this method may block. This provide better performance when user has large group membership via
      1) avoid set->list->set conversion for the caller UGI/PermissionCheck
      2) fast lookup using contains() via Set instead of List
      Parameters:
      user - User's name
      Returns:
      the group memberships of the user as set
      Throws:
      IOException - if user does not exist

    • getBackgroundRefreshSuccess

      public long getBackgroundRefreshSuccess()

    • getBackgroundRefreshException

      public long getBackgroundRefreshException()

    • getBackgroundRefreshQueued

      public long getBackgroundRefreshQueued()

    • getBackgroundRefreshRunning

      public long getBackgroundRefreshRunning()

    • refresh

      public void refresh()
      Refresh all user-to-groups mappings.

    • cacheGroupsAdd

      public void cacheGroupsAdd(List<String> groups)
      Add groups to cache
      Parameters:
      groups - list of groups to add to cache

    • getUserToGroupsMappingService

      public static Groups getUserToGroupsMappingService()
      Get the groups being used to map user-to-groups.
      Returns:
      the groups being used to map user-to-groups.

    • getUserToGroupsMappingService

      public static Groups getUserToGroupsMappingService(Configuration conf)
      Get the groups being used to map user-to-groups.
      Parameters:
      conf - configuration.
      Returns:
      the groups being used to map user-to-groups.

    • getUserToGroupsMappingServiceWithLoadedConfiguration

      @Private public static Groups getUserToGroupsMappingServiceWithLoadedConfiguration(Configuration conf)
      Create new groups used to map user-to-groups with loaded configuration.
      Parameters:
      conf - configuration.
      Returns:
      the groups being used to map user-to-groups.

    • reset

      @VisibleForTesting public static void reset()