how to impliment #acl (#ACL : Access control list)in #hadoop

ACL (Access Control Lists) can be implemented in Hadoop to control access to HDFS (Hadoop Distributed File System) files and directories. Here are the steps to implement ACL in Hadoop:

1. Enable ACL in HDFS by adding the following property to the hdfs-site.xml configuration file:

<property>

  <name>dfs.namenode.acls.enabled</name>

  <value>true</value>

</property>

2. Restart the HDFS service to apply the configuration changes.

3. Set ACL for a file or directory using the hdfs dfs -setfacl command. For example, to set ACL for a directory named "directory" and give the user "shashwat" read and write permissions, use the following command:

hdfs dfs -setfacl -m username:shashwat:rwx directory

4. Check the ACL of a file or directory using the hdfs dfs -getfacl command. For example, to check the ACL of the "directory" directory, use the following command:

hdfs dfs -getfacl directory

This will display the ACL entries for the directory, including the permissions and users/groups assigned.

Note that ACL can also be set for groups and masks, in addition to users. The mask is used to restrict the maximum permissions that can be assigned to a file or directory. For example, if the mask is set to "r-x", then the maximum permission that can be assigned to a user/group is read and executed.

Also, keep in mind that ACLs only apply to HDFS, and do not affect access to other components in the Hadoop ecosystem such as MapReduce or YARN.