big-data/hadoop
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

HADOOP-6661. User document for UserGroupInformation.doAs. Contributed by Jitendra Pandey.

Browse Source 
git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@951227 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Jakob Homan 2010-06-04 00:41:13 +00:00
parent c6bc36580a
commit 908fd4506f
3 changed files with 110 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
CHANGES.txt
View File

@ -38,6 +38,9 @@ Trunk (unreleased changes)
HADOOP-6714. Resolve compressed files using CodecFactory in FsShell::text.
(Patrick Angeles via cdouglas)
HADOOP-6661. User document for UserGroupInformation.doAs.
(Jitendra Pandey via jghoman)
BUG FIXES
HADOOP-6638. try to relogin in a case of failed RPC connection (expired tgt)
only in case the subject is loginUser or proxyUgi.realUser. (boryas)

106
src/docs/src/documentation/content/xdocs/Superusers.xml Normal file
View File

@ -0,0 +1,106 @@
<?xml version="1.0"?>
<!--
Copyright 2002-2004 The Apache Software Foundation
Licensed 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.
-->
<!DOCTYPE document PUBLIC "-//APACHE//DTD Documentation V2.0//EN"
"http://forrest.apache.org/dtd/document-v20.dtd">
<document>
<header>
<title>
Superusers Acting On Behalf Of Other Users
</title>
</header>
<body>
<section>
<title> Introduction </title>
<p>
This document describes how a superuser can submit jobs or access hdfs on behalf of another user in a secured way.
</p>
</section>
<section>
<title> Use Case </title>
<p>
The code example described in the next section is applicable for the following use case.
</p>
<p>
A superuser with username 'super' wants to submit job and access hdfs on behalf of a user joe. The superuser has kerberos credentials but user joe doesn't have any. The tasks are required to run as user joe and any file accesses on namenode are required to be done as user joe. It is required that user joe can connect to the namenode or job tracker on a connection authenticated with super's kerberos credentials. In other words super is impersonating the user joe.
</p>
</section>
<section>
<title> Code example </title>
<p>
In this example super's kerberos credentials are used for login and a proxy user ugi object is created for joe. The operations are performed within the doAs method of this proxy user ugi object.
</p>
<source>
...
//Create ugi for joe. The login user is 'super'.
UserGroupInformation ugi =
UserGroupInformation.createProxyUser("joe", UserGroupInformation.getLoginUser());
ugi.doAs(new PrivilegedExceptionAction&lt;Void&gt;() {
public Void run() throws Exception {
//Submit a job
JobClient jc = new JobClient(conf);
jc.submitJob(conf);
//OR access hdfs
FileSystem fs = FileSystem.get(conf);
fs.mkdir(someFilePath);
}
}
</source>
</section>
<section>
<title> Configurations </title>
<p>
The superuser must be configured on namenode and jobtracker to be allowed to impersonate another user. Following configurations are required.
</p>
<source>
&lt;property&gt;
&lt;name&gt;hadoop.proxyuser.super.groups&lt;/name&gt;
&lt;value&gt;group1,group2&lt;/value&gt;
&lt;description&gt;Allow the superuser super to impersonate any members of the group group1 and group2&lt;/description&gt;
&lt;/property&gt;
&lt;property&gt;
&lt;name&gt;hadoop.proxyuser.super.hosts&lt;/name&gt;
&lt;value&gt;host1,host2&lt;/value&gt;
&lt;description&gt;The superuser can connect only from host1 and host2 to impersonate a user&lt;/description&gt;
&lt;/property&gt;
</source>
<p>
If these configurations are not present, impersonation will not be allowed and connection will fail.
</p>
</section>
<section>
<title> Caveats </title>
<p>
The superuser must have kerberos credentials to be able to impersonate another user. It cannot use delegation tokens for this feature. It would be wrong if superuser adds its own delegation token to the proxy user ugi, as it will allow the proxy user to connect to the service with the privileges of the superuser.
</p>
<p>
However, if the superuser does want to give a delegation token to joe, it must first impersonate joe and get a delegation token for joe, in the same way as the code example above, and add it to the ugi of joe. In this way the delegation token will have the owner as joe.
</p>
</section>
</body>
</document>

1
src/docs/src/documentation/content/xdocs/site.xml
View File

@ -42,6 +42,7 @@ See http://forrest.apache.org/docs/linking.html for more info.
<fsshell label="File System Shell" href="file_system_shell.html" />
<SLA label="Service Level Authorization" href="service_level_auth.html"/>
<native_lib label="Native Libraries" href="native_libraries.html" />
<superusers label="Superusers Acting On Behalf Of Other Users" href="Superusers.html"/>
</docs>
<docs label="Miscellaneous">