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From "Wei-Chiu Chuang (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HADOOP-12782) Faster LDAP group name resolution with ActiveDirectory
Date Mon, 08 Feb 2016 22:33:39 GMT

     [ https://issues.apache.org/jira/browse/HADOOP-12782?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Wei-Chiu Chuang updated HADOOP-12782:
    Attachment: HADOOP-12782.001.patch

Rev01: implemented fast ldap group name lookup, the associated test case, and associated documentation.

In this implementation, there are basically three cases: 
# general scenario, perform two ldap queries per group lookup.
# If the server supports posix semantics, perform two ldap queries using posix gid/uid to
find groups of the user
# (new implementation) perform one ldap query per group lookup, if fast lookup is enabled
(The server must be an Active Directory, no recursive group membership and use CN attribute
to identify a group's name)

To enable this feature, set hadoop.security.group.mapping.ldap.search.filter.group=ldapFastLookup.

I also updated the first two scenarios so that more verbose message will be logged in case
of exceptions. (supportability)

Finally, a new test file TestLdapGroupsMappingWithFastLookup is added that tests the new feature.
The test (as well as TestLdapGroupsMapping and TestLdapGroupsMappingWithPosixGroup) all passed

> Faster LDAP group name resolution with ActiveDirectory
> ------------------------------------------------------
>                 Key: HADOOP-12782
>                 URL: https://issues.apache.org/jira/browse/HADOOP-12782
>             Project: Hadoop Common
>          Issue Type: Improvement
>            Reporter: Wei-Chiu Chuang
>            Assignee: Wei-Chiu Chuang
>         Attachments: HADOOP-12782.001.patch
> The typical LDAP group name resolution works well under typical scenarios. However, we
have seen cases where a user is mapped to many groups (in an extreme case, a user is mapped
to more than 100 groups). The way it's being implemented now makes this case super slow resolving
groups from ActiveDirectory.
> The current LDAP group resolution implementation sends two queries to a ActiveDirectory
server. The first query returns a user object, which contains DN (distinguished name). The
second query looks for groups where the user DN is a member. If a user is mapped to many groups,
the second query returns all group objects associated with the user, and is thus very slow.
> After studying a user object in ActiveDirectory, I found a user object actually contains
a "memberOf" field, which is the DN of all group objects where the user belongs to. Assuming
that an organization has no recursive group relation (that is, a user A is a member of group
G1, and group G1 is a member of group G2), we can use this properties to avoid the second
query, which can potentially run very slow.
> I propose that we add a configuration to only enable this feature for users who want
to reduce group resolution time and who does not have recursive groups, so that existing behavior
will not be broken.

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