Granting IAM Users Under an Account the Access to a Bucket and the Resources in It

Scenario

This topic describes how to grant IAM users the permissions to access OBS buckets and resources in them.

The following describes how to grant the permissions to upload and download objects in a bucket. If you need to configure other specified permissions, configure the corresponding permissions in the bucket policy and IAM permissions.

Recommended Configuration

To grant permissions to IAM users under other accounts, you need to configure both bucket policies and IAM permissions.

For example, to allow IAM user A of account A to access bucket B of account B, you need to:

1. Configure a bucket policy that allows IAM user A to access bucket B.
2. Configure IAM permissions for account A to allow IAM user A to access bucket B.

The permissions allowed by both bucket policies and IAM permissions take effect.

Configuration Precautions

After the configuration is complete, the authorized IAM user can upload and download objects through APIs. In addition, the user can upload and download objects by mounting external buckets on OBS Browser+. To add external buckets, the ListBucket permission is also required. Currently, access to buckets of other accounts is not allowed on OBS Console.

Procedure 1: Configure a Bucket Policy That Allows Specified Operations

The bucket owner or a user who has the permission to configure bucket policies needs to configure a bucket policy that allows specified operations.

1. In the navigation pane of OBS Console, choose Object Storage.
2. In the bucket list, click the bucket name you want to go to the Overview page.
3. In the navigation pane, choose Permissions.
4. On the Bucket Policies page, click Create Bucket Policy under Custom Bucket Policies.
5. Configure a bucket policy that allows uploads and downloads.

   Table 1 Parameters for creating a bucket policy

   Parameter	Description
   Policy Mode	Select Customized.
   Effect	Select Allow.
   Principal	Select Include > Other account. Account ID: Enter the ID of the account which you want to grant permissions to. You can obtain it from the My Credentials page of the account or the IAM user. User ID: Enter the ID of the IAM user under the authorized account. You can obtain the ID on the My Credentials page of the IAM user. The wildcard character (*) is supported, indicating that the setting takes effect for all IAM users under the account.
   Resources	Choose Include > Specific resources. Resource Name: Enter the object or the set of objects that will be accessed. For one object, enter object name. For a set of objects, enter object name prefix + *, * + object name suffix, or *. Set this parameter to * if all objects need to be downloaded.
   Actions	Include Action Name: GetObject GetObjectVersion PutObject (Optional) ListBucket: Select this operation if you need to use OBS Browser+ to add external buckets. To configure other specified operation permissions on objects, select the corresponding actions. For details about the actions supported by OBS, see Action/NotAction.

6. Click OK. The bucket policy that allows upload and download is created.
7. (Optional) Click Create Bucket Policy again to configure a bucket policy that allows objects in the bucket to be listed. (Perform this step when you need to use OBS Browser+ to add external buckets.)

   Table 2 Parameters for creating a bucket policy

   Parameter	Description
   Policy Mode	Select Customized.
   Effect	Select Allow.
   Principal	Select Include > Other account. Account ID: Enter the ID of the account which you want to grant permissions to. You can obtain it from the My Credentials page of the account or the IAM user. User ID: Enter the ID of the IAM user under the authorized account. You can obtain the ID on the My Credentials page of the IAM user. The wildcard character (*) is supported, indicating that the setting takes effect for all IAM users under the account.
   Resources	Select Include > Entire bucket.
   Actions	Include Action Name: ListBucket To configure other specified permissions on buckets, select the corresponding actions. For details about the actions supported by OBS, see Action/NotAction.

8. Click OK. The bucket policy for listing objects in the bucket is created.

Procedure 2: Configure an IAM Permission That Allows Specified Operations

The account to which the authorized IAM user belongs needs to configure the IAM permission for the IAM user to perform specified operations on the specified bucket. The allowed operations must be the same as those specified in the bucket policy.

1. Log in to the management console using a cloud service account.
2. On the top menu bar, choose Service List > Management & Deployment > Identity and Access Management. The IAM console is displayed.
3. In the navigation pane, choose Policies.
4. Click Create Custom Policy in the upper right corner.
5. Configure parameters for a custom policy.

   Table 3 Parameters for configuring a custom policy

   Parameter	Description
   Policy Name	Name of the custom policy
   Policy View	Set this parameter based on your own habits. Visual editor is used here.
   Policy Content	Select Allow. Select Object Storage Service (OBS). Select the actions to be authorized. ReadOnly > obs:bucket:ListBucketVersions and obs:object:GetObjectVersion ReadWrite > obs:object:PutObject ListOnly > obs:bucket:ListBucket (Select this operation if you need to use OBS Browser+ to add external buckets.) Choose Specific > object to specify an object resource. The specified object or object set must be consistent with the bucket policy. Select Any if the resource set in the bucket policy is *. If the resource specified in the bucket policy is a specified object or a set of objects, you need to specify the object or the set of objects the same as that in the bucket policy through the resource path. [Format] obs:*:*:object:bucket name/object name Select Any as the bucket policy in this example is set to *. Choose Specific > bucket > Specify resource path to specify bucket resources. Click Add Resource Path and enter the name of the authorized bucket in the Path text box, for example, example-bucket. The complete path of the resource is as follows: OBS:*:*:bucket:example-bucket.
   Scope	The default value is Global services.

6. Click OK. The custom policy is created.
7. Create a user group and assign permissions.

   Add the created custom policy to the user group by following the instructions in the IAM document.

8. Add the IAM user you want to authorize to the created user group by referring to Adding Users to or Removing Users from a User Group.
   

   Due to data caching, it takes about 10 to 15 minutes for a custom policy to take effect after the authorization.