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 an account, 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.

Precautions

After configuration, the IAM user can upload and download objects through APIs or SDKs. 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: The Bucket Owner Configures a Bucket Policy.

The bucket owner or a user who has the permission to configure bucket policies needs to configure a bucket policy that allows IAM users under an account to perform specified operations on the bucket.

In this example, account B (owner of bucket B) configures a bucket policy that allows IAM user A of account A to upload objects to and download objects from bucket B of account B.

1. In the navigation pane of OBS Console, choose Buckets.
2. In the bucket list, click the bucket name you want to go to the Objects page.
3. In the navigation pane, choose Permissions > Bucket Policies.
4. On the Bucket Policies page, click Create.
5. Configure a bucket policy.
   Figure 1 Configuring a bucket policy
   

   Table 1 Parameters for configuring a bucket policy

   Parameter	Description
   Policy view	Select Visual Editor or JSON based on your own habits. Visual Editor is used here.
   Policy Name	Enter a policy name.
   Effect	Select Allow.
   Principal	Select Other accounts. Enter the account ID and IAM user ID in the format of Account ID/IAM user ID. To specify multiple IAM users, enter each one on a separate line. An asterisk (*) indicates all accounts or IAM users. NOTE: The account ID and IAM user ID can be obtained on the My Credentials page. The following describes different authorization scenarios: Granting permissions to all accounts and IAM users: Enter */*. Granting permissions to an account and all IAM users under the account: Enter Account ID/*. Granting permissions to a specific IAM user under an account: Enter Account ID/IAM user ID. Delegated accounts: Enter the ID of a delegating account and an agency name. NOTE: The format is Account ID/Agency name. To specify multiple agencies, enter each one on a separate line. You can specify one or more common accounts or delegated accounts. Either of the two types of accounts must be specified.
   Resources	Select Current bucket and Specified objects. Enter an object name prefix for the resource path. NOTE: You can click Add to specify multiple resource paths. You can specify a specific object, an object set, or a directory. * indicates all objects in the bucket. To specify a specific object, enter the object name. To specify a set of objects, enter Object name prefix*, *Object name suffix, or *.
   Actions	Choose Customize. Select actions: GetObject (to obtain object content and metadata) GetObjectVersion (to obtain the content and metadata of a specified object version) PutObject (to upload objects using PUT and POST, upload parts, initiate multipart uploads, and assemble parts) (Optional) ListBucket (to list objects in the bucket and obtain the bucket metadata) NOTE: After the ListBucket permission is granted, the authorized account can access the bucket from OBS Browser+ by adding an external bucket. To grant other permissions, select required actions based on actions supported by OBS.

6. Confirm and click Create.

Procedure 2: The Account Grants Permissions to IAM Users Under It.

The account (not the bucket owner) needs to grant permissions to its IAM users to perform specified operations on the bucket. (The allowed operations must be the same as those allowed in the bucket policy.)

In this example, account A needs to grant IAM user A the permissions to upload objects to and download objects from bucket B of account B.

1. Log in to Huawei Cloud and click Console in the upper right corner.
2. On the console, hover over the username in the upper right corner, and choose Identity and Access Management from the drop-down list.
3. In the navigation pane, choose Permissions > Policies/Roles > Create Custom Policy.
4. Configure a custom policy.
   Figure 2 Configuring a custom policy
   

   Table 2 Parameters for configuring a custom policy

   Parameter	Description
   Policy Name	Enter a policy name.
   Policy View	Select Visual editor or JSON 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.) If you need to configure permissions on other actions, select the corresponding actions. For details, see Bucket-Related Actions and Object-Related Actions. 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.

5. Click OK.
6. Create a user group and assign permissions.

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

7. Add the IAM user you want to authorize to the created user group.
   

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

Verification

In cross-account authorization scenarios, authorized users can access the buckets and objects via APIs or SDKs, or by adding external buckets through OBS Browser+.