Synchronizing IAM Users to MRS

IAM user synchronization is to synchronize IAM users bound with MRS policies to the MRS system and create accounts with the same usernames but different passwords as the IAM users. Then, you can use an IAM username (the password needs to be reset by user admin of Manager) to log in to Manager for cluster management, and submit jobs on the GUI in a cluster with Kerberos authentication enabled.

Table 1 compares IAM users' permission policies and the synchronized users' permissions on MRS. For details about the default permissions on Manager, see Default Permissions of the MRS Cluster.

**Table 1** Policy and permission mapping after synchronization
Policy Type	IAM Policy	User's Default Permissions on MRS After Synchronization	Have Permission to Perform the Synchronization	Have Permission to Submit Jobs
Fine-grained	MRS ReadOnlyAccess	Manager_viewer	No	No
	MRS CommonOperations	Manager_viewer default launcher-job	No	Yes
	MRS FullAccess	Manager_administrator Manager_auditor Manager_operator Manager_tenant Manager_viewer System_administrator default launcher-job	Yes	Yes
RBAC	MRS Administrator	Manager_administrator Manager_auditor Manager_operator Manager_tenant Manager_viewer System_administrator default launcher-job	No	Yes
	Server Administrator, Tenant Guest, and MRS Administrator	Manager_administrator Manager_auditor Manager_operator Manager_tenant Manager_viewer System_administrator default launcher-job	Yes	Yes
	Tenant Administrator	Manager_administrator Manager_auditor Manager_operator Manager_tenant Manager_viewer System_administrator default launcher-job	Yes	Yes
Custom	Custom policy	Manager_viewer default launcher-job	If custom policies use RBAC policies as a template, refer to the RBAC policies. If custom policies use fine-grained policies as a template, refer to the fine-grained policies. The fine-grained policies are recommended.	Yes

For easier permission management, use fine-grained policies instead of RBAC. Within fine-grained policies, the Deny action takes precedence over all other actions.

To synchronize IAM users, a user must either have the Tenant Administrator role, or simultaneously hold the Server Administrator, Tenant Guest, and MRS Administrator roles.
A user with the action:mrs:cluster:syncUser policy can synchronize IAM users.

Constraints on IAM User Synchronization

Because of restrictions in open-source components, some IAM users cannot be synchronized. For example, usernames with special characters such as periods (.) or at signs (@), or usernames with only one character, are not supported. To ensure successful synchronization of IAM users, the usernames must conform to the naming conventions defined by MRS Manager.

In MRS 3.x and later versions, usernames must contain 2 to 64 characters. Valid characters include digits, case-insensitive letters, underscores (_), hyphens (-), periods (.), and spaces. Usernames must not begin with a hyphen (-) or contain consecutive periods (..). Each username must be unique within the system or operating system.
In versions earlier than MRS 3.x, usernames must contain 3 to 32 characters. Valid characters include letters, digits, spaces, hyphens (-), and underscores (_). Usernames must not begin with a digit, nor duplicate existing operating system accounts such as root or omm.

Synchronizing IAM Users

Create a user and authorize the user to use MRS. For details, see Creating an IAM User and Granting MRS Permissions.
Log in to the MRS management console and create a cluster. For details, see Buying a Custom MRS Cluster.
In the navigation pane on the left, choose Active Clusters. Click a cluster name to go to the cluster details page.
On the Dashboard tab page, click Synchronize next to IAM User Sync to synchronize IAM users.
In the IAM User Sync dialog box, search for the user group to which the IAM user to be synchronized belongs and click the user group name. In the User column, select the desired IAM user and click Synchronize.
- To synchronize all users, select All in the To Synchronize tab.
- If you select only user groups, users will not be synchronized. To synchronize users, specific usernames within those groups must be selected.
- All user groups are displayed in the IAM User Sync window. User groups and usernames that cannot be selected cannot be synchronized.
After a synchronization request is sent, choose Operation Logs in the navigation tree on the left of the MRS console to check whether the synchronization is successful. For details about the logs, see Viewing MRS Operation Logs.
After the synchronization is successful, use the user synchronized with IAM to perform subsequent operations.
- When the policy of the user group to which the IAM user belongs changes from MRS ReadOnlyAccess to MRS CommonOperations, MRS FullAccess, or MRS Administrator, wait for 5 minutes until the new policy takes effect after the synchronization is complete because the SSSD (System Security Services Daemon) cache of cluster nodes needs time to be updated. Then, submit a job. Otherwise, the job may fail to be submitted.
- When the policy of the user group to which the IAM user belongs changes from MRS CommonOperations, MRS FullAccess, or MRS Administrator to MRS ReadOnlyAccess, wait for 5 minutes until the new policy takes effect after the synchronization is complete because the SSSD cache of cluster nodes needs time to be updated.
- After you click Synchronize on the right side of IAM User Sync, the cluster details page is blank for a short time, because user data is being synchronized. The page will be properly displayed after the data synchronization is complete.
- Submitting jobs in a security cluster: Users can submit jobs using the job management function on the GUI in the security cluster. For details, see Running a MapReduce Job.
- All tabs are displayed on the cluster details page, including Components, Tenants, and Backups & Restorations.
- Logging in to Manager
  1. Log in to Manager as user admin. For details, see Accessing MRS Manager.
  2. Initialize the password of the user synchronized with IAM. For details, see Initializing MRS Cluster User Passwords.
  3. Modify the role bound to the user group to which the user belongs to control user permissions on Manager. For details, see Managing MRS Cluster User Groups. For details about how to create and modify a role, see Creating a Role. After the component role bound to the user group to which the user belongs is modified, it takes some time for the role permissions to take effect.
  4. Log in to Manager using the user synchronized with IAM and the password after the initialization in 7.b.
  If an IAM user's permission changes, go to Step 4 to perform second synchronization. After the second synchronization, a system user's effective permissions are determined as the union of the permissions defined in the IAM system policy and those granted through roles added by the user in MRS Manager. After the second synchronization, the effective permissions of a custom user are determined solely by the permissions configured on MRS Manager.
  - System user: An IAM user is considered a system user if every user group to which they belong is bound to system policies (including RBAC and fine-grained policies).
  - Custom user: An IAM user is considered a custom user if the user group to which they belong is bound to any custom policy.

Undo IAM user synchronization.

To undo the synchronization of an IAM user, select the user in the User column in the Synchronized tab and click Undo Sync.

To undo the synchronization of all users in an IAM user group, select the user group in the User Group column in the Synchronized tab and click Undo Sync.