From 347cf6e176222b997f63b13136289352d7b14982 Mon Sep 17 00:00:00 2001
From: Todd Lipcon <todd@apache.org>
Date: Tue, 15 Jan 2013 20:43:32 +0000
Subject: [PATCH] HADOOP-8712. Change default hadoop.security.group.mapping to
 JniBasedUnixGroupsNetgroupMappingWithFallback. Contributed by Robert Parker.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1433624 13f79535-47bb-0310-9956-ffa450edef68
---
 hadoop-common-project/hadoop-common/CHANGES.txt      |  3 +++
 .../src/main/resources/core-default.xml              | 12 ++++++++++--
 .../content/xdocs/hdfs_permissions_guide.xml         |  9 +++++----
 3 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/hadoop-common-project/hadoop-common/CHANGES.txt b/hadoop-common-project/hadoop-common/CHANGES.txt
index 529d95553d2..e044be09968 100644
--- a/hadoop-common-project/hadoop-common/CHANGES.txt
+++ b/hadoop-common-project/hadoop-common/CHANGES.txt
@@ -436,6 +436,9 @@ Release 2.0.3-alpha - Unreleased
     HADOOP-9192. Move token related request/response messages to common.
     (suresh)
 
+    HADOOP-8712. Change default hadoop.security.group.mapping to
+    JniBasedUnixGroupsNetgroupMappingWithFallback (Robert Parker via todd)
+
   OPTIMIZATIONS
 
     HADOOP-8866. SampleQuantiles#query is O(N^2) instead of O(N). (Andrew Wang
diff --git a/hadoop-common-project/hadoop-common/src/main/resources/core-default.xml b/hadoop-common-project/hadoop-common/src/main/resources/core-default.xml
index b020610ba79..27ad539c9fa 100644
--- a/hadoop-common-project/hadoop-common/src/main/resources/core-default.xml
+++ b/hadoop-common-project/hadoop-common/src/main/resources/core-default.xml
@@ -80,9 +80,17 @@
 
 <property>
   <name>hadoop.security.group.mapping</name>
-  <value>org.apache.hadoop.security.ShellBasedUnixGroupsMapping</value>
+  <value>org.apache.hadoop.security.JniBasedUnixGroupsMappingWithFallback</value>
   <description>
-    Class for user to group mapping (get groups for a given user) for ACL
+    Class for user to group mapping (get groups for a given user) for ACL. 
+    The default implementation,
+    org.apache.hadoop.security.JniBasedUnixGroupsMappingWithFallback, 
+    will determine if the Java Native Interface (JNI) is available. If JNI is 
+    available the implementation will use the API within hadoop to resolve a 
+    list of groups for a user. If JNI is not available then the shell 
+    implementation, ShellBasedUnixGroupsMapping, is used.  This implementation 
+    shells out to the Linux/Unix environment with the 
+    <code>bash -c groups</code> command to resolve a list of groups for a user.
   </description>
 </property>
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/docs/src/documentation/content/xdocs/hdfs_permissions_guide.xml b/hadoop-hdfs-project/hadoop-hdfs/src/main/docs/src/documentation/content/xdocs/hdfs_permissions_guide.xml
index cfb46edfc08..af260fa93c9 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/docs/src/documentation/content/xdocs/hdfs_permissions_guide.xml
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/docs/src/documentation/content/xdocs/hdfs_permissions_guide.xml
@@ -92,10 +92,11 @@ There is no provision within HDFS for creating user identities, establishing gro
 
 <section><title>Group Mapping</title>
 <p>
-Once a username has been determined as described above, the list of groups is determined by a <em>group mapping
-service</em>, configured by the <code>hadoop.security.group.mapping</code> property.
-The default implementation, <code>org.apache.hadoop.security.ShellBasedUnixGroupsMapping</code>, will shell out
-to the Unix <code>bash -c groups</code> command to resolve a list of groups for a user.
+Once a username has been determined as described above, the list of groups is 
+determined by a <em>group mapping service</em>, configured by the 
+<code>hadoop.security.group.mapping</code> property. Refer to the 
+core-default.xml for details of the <code>hadoop.security.group.mapping</code>
+implementation.
 </p>
 <p>
 An alternate implementation, which connects directly to an LDAP server to resolve the list of groups, is available