Configuring the ZooKeeper Permissions

Scenario

Configure znode permission of ZooKeeper.

ZooKeeper uses an access control list (ACL) to implement znode access control. The ZooKeeper client specifies a znode ACL, and the ZooKeeper server determines whether a client that requests for a znode has related operation permission according to the ACL. ACL configuration involves the following four operations:

• Check znode ACLs in ZooKeeper.
• Add znode ACLs to ZooKeeper.
• Modify znode ACLs in ZooKeeper.
• Delete znode ACLs from ZooKeeper.

  The ZooKeeper ACL permission is described as follows:

  ZooKeeper supports five types of permission, create, delete, read, write, and admin. ZooKeeper permission control is of a znode level. That is, the permission configuration for a parent znode is not inherited by its child znodes. The ZooKeeper znode default permission is world:anyone: cdrwa. That is, any user has all permissions.

ACL has three parts:

The first part is the authentication type. For example, world indicates all authentication types and sasl indicates the kerberos authentication type.

The second part is the account. For example, anyone indicates any user.

The third part is permission. For example, cdrwa indicates all permissions.

In particular, because starting the client in common mode does not need authentication, ACL with sasl authentication type cannot be used in common mode. Authentications of sasl scheme in this document are performed in clusters that have the security mode enabled.

Impact on the System

Modifying ZooKeeper ACLs is a critical operation. If znode permission is modified in ZooKeeper, other users may have no permission to access the znode and some system functions are abnormal. In 3.5.6 and later versions, users must have the read permission for the getAcl operation.

Prerequisites

• The ZooKeeper client has been installed in a directory, for example, /opt/client.
• You have obtained the username and password of an MRS cluster administrator.

Procedure

Start the ZooKeeper client.

1. Log in to the server where the ZooKeeper client is installed as user root.
2. Run the following command to go to the client installation directory:

   cd /opt/client

3. Run the following command to configure environment variables:

   source bigdata_env

4. Run the following command and enter the user password to authenticate the user's identity (This step is required only for clusters in security mode, and user userA is provided as an example of an authorized user.):

   kinit userA

5. On the ZooKeeper client, run the following command to go to the ZooKeeper command-line interface (CLI):

   sh zkCli.sh -server ZooKeeper plane IP address of any instance:clientPort

   The default clientPort is 2181.

   Example: sh zkCli.sh -server 192.168.0.151:2181

6. Run the ls command to view the znode list in ZooKeeper. For example, you can view the list of znodes in the root directory.

   ls /

   [zk: 192.168.0.151:2181(CONNECTED) 1] ls /
   [hadoop-flag, hadoop-ha, test, test2, test3, test4, test5, test6, zookeeper]

View the ZooKeeper znode ACL.

7. Start the ZooKeeper client.
8. Run the getAcl command to view znodes. The following command can be used to view the created znode ACL named test:

   getAcl /znode name

   [zk: 192.168.0.151:2181(CONNECTED) 2] getAcl /test
   'world,'anyone
   : cdrwa

Add a ZooKeeper znode ACL.

9. Start the ZooKeeper client.
10. View the old ACL information to check whether the current account has the permission to modify the znode ACL information (a permission). If no, use kinit to switch to a user that has the permission and restart the ZooKeeper client.
    getAcl /znode name

     [zk: 192.168.0.151:2181(CONNECTED) 3] getAcl /test
    'world,'anyone
    : cdrwa

11. Run the setAcl command to add an ACL. The command for adding an ACL is as follows:

    setAcl /test world:anyone:cdrwa,sasl: username@: <system domain name>:ACL value

    For example, to create the ACL of user admin to the test znode, run the following command:

    setAcl /test world:anyone:cdrwa,sasl:userA@HADOOP.COM:cdrwa

    

    When adding a new ACL, reserve the existing ones. The new and old ACLs are separated by a comma. The newly added ACL has three parts:

    • The first part is the authentication type. For example, sasl indicates kerberos authentication.
    • The second part is the account. For example, userA@HADOOP.COM indicates user userA.
    • The third part is permission. For example, cdrwa indicates all permissions.

12. After adding the ACL, run the getAcl command to check whether the permission is added successfully:

    getAcl /znode name

    [zk: 192.168.0.151:2181(CONNECTED) 4] getAcl /test 
    'world,'anyone
    : cdrwa
    'sasl,'userA@<System domain name>
    : cdrwa

Modify the ZooKeeper znode ACL.

13. Start the ZooKeeper client.
14. View the old ACL information to check whether the current account has the permission to modify the znode ACL information (a permission). If no, use kinit to switch to a user that has the permission and restart the ZooKeeper client.

    getAcl /znode name

    [zk: 192.168.0.151:2181(CONNECTED) 5] getAcl /test 
    'world,'anyone
    : cdrwa
    'sasl,'userA@<System domain name>
    : cdrwa

15. Run the setAcl command to modify an ACL. The command for adding an ACL is as follows:

    setAcl /test sasl:Username@<System domain name>:ACL value

    For example, to reserve all permissions of user userA and delete the rw permission of user anyone, run the following command:

    setAcl /test sasl:userA@HADOOP.COM:cdrwa

16. After modifying the ACL, run the getAcl command to check whether the permission is modified successfully:

    getAcl /znode name

    [zk: 192.168.0.151:2181(CONNECTED) 6] getAcl /test 
    'sasl,'userA@<System domain name>
    : cdrwa

Delete the ZooKeeper znode ACL.

17. Start the ZooKeeper client.
18. View the old ACL information to check whether the current account has the permission to modify the znode ACL information (a permission). If no, use kinit to switch to a user that has the permission and restart the ZooKeeper client.

    getAcl /znode name

    [zk: 192.168.0.151:2181(CONNECTED) 5] getAcl /test 
    'world,'anyone
    : rw
    'sasl,'userA@<System domain name>
    : cdrwa

19. Run the setAcl command to add an ACL. The command for adding an ACL is as follows:

    setAcl /test sasl:Username@<System domain name>:ACL value

    For example, to reserve all permissions of user userA and delete the rw permission of user anyone, run the following command:

    setAcl /test sasl:userA@HADOOP.COM:cdrwa

20. After modifying the ACL, run the getAcl command to check whether the permission is modified successfully:

    getAcl /znode name

    [zk: 192.168.0.151:2181(CONNECTED) 6] getAcl /test
    'sasl,'userA@<System domain name>
    : cdrwa