Overview of managing access permissions to your AWS Directory Service resources

Every AWS resource is owned by an AWS account, and permissions to create or access the resources are governed by permissions policies. An account administrator can attach permissions policies to IAM identities (that is, users, groups, and roles), and some services (such as AWS Lambda) also support attaching permissions policies to resources.

Note

An account administrator (or administrator user) is a user with administrator privileges. For more information, see IAM best practices in the IAM User Guide.

AWS Directory Service resources and operations

In AWS Directory Service, the primary resource is a directory. AWS Directory Service supports directory snapshot resources as well. However, you can create snapshots only in the context of an existing directory. Therefore, a snapshot is referred to as a subresource.

These resources have unique Amazon Resource Names (ARNs) associated with them as shown in the following table.

Resource Type	ARN Format
Directory	arn:aws:ds:region:account-id:directory/external-directory-id
Snapshot	arn:aws:ds:region:account-id:snapshot/external-snapshot-id

AWS Directory Service provides a set of operations to work with the appropriate resources. For a list of available operations, see Directory Service Actions.

Understanding resource ownership

A resource owner is the AWS account that created a resource. That is, the resource owner is the AWS account of the principal entity (the root account, an IAM user, or an IAM role) that authenticates the request that creates the resource. The following examples illustrate how this works:

• If you use the root account credentials of your AWS account to create an AWS Directory Service resource, such as a directory, your AWS account is the owner of that resource.

• If you create an IAM user in your AWS account and grant permissions to create AWS Directory Service resources to that user, the user can also create AWS Directory Service resources. However, your AWS account, to which the user belongs, owns the resources.

• If you create an IAM role in your AWS account with permissions to create AWS Directory Service resources, anyone who can assume the role can create AWS Directory Service resources. Your AWS account, to which the role belongs, owns the AWS Directory Service resources.

Managing access to resources

A permissions policy describes who has access to what. The following section explains the available options for creating permissions policies.

Note

This section discusses using IAM in the context of AWS Directory Service. It doesn't provide detailed information about the IAM service. For complete IAM documentation, see What is IAM? in the IAM User Guide. For information about IAM policy syntax and descriptions, see IAM JSON policy reference in the IAM User Guide.

Policies attached to an IAM identity are referred to as identity-based policies (IAM polices) and policies attached to a resource are referred to as resource-based policies. AWS Directory Service supports only identity-based policies (IAM policies).

Topics

• Identity-based policies (IAM policies)
• Resource-based policies

Identity-based policies (IAM policies)

You can attach policies to IAM identities. For example, you can do the following:

• Attach a permissions policy to a user or a group in your account – An account administrator can use a permissions policy that is associated with a particular user to grant permissions for that user to create an AWS Directory Service resource, such as a new directory.

• Attach a permissions policy to a role (grant cross-account permissions) – You can attach an identity-based permissions policy to an IAM role to grant cross-account permissions.

  For more information about using IAM to delegate permissions, see Access management in the IAM User Guide.

The following permissions policy grants permissions to a user to run all of the actions that begin with Describe. These actions show information about an AWS Directory Service resource, such as a directory or snapshot. Note that the wildcard character (*) in the Resource element indicates that the actions are allowed for all AWS Directory Service resources owned by the account.

{
   "Version":"2012-10-17",
   "Statement":[
      {
         "Effect":"Allow",
         "Action":"ds:Describe*",
         "Resource":"*"
      }
   ]
}

For more information about using identity-based policies with AWS Directory Service, see Using identity-based policies (IAM policies) for AWS Directory Service. For more information about users, groups, roles, and permissions, see Identities (users, groups, and roles) in the IAM User Guide.

Resource-based policies

Other services, such as Amazon S3, also support resource-based permissions policies. For example, you can attach a policy to an S3 bucket to manage access permissions to that bucket. AWS Directory Service doesn't support resource-based policies.

Specifying policy elements: Actions, effects, resources, and principals

For each AWS Directory Service resource, the service defines a set of API operations. For more information, see AWS Directory Service resources and operations. For a list of available API operations, see Directory Service Actions.

To grant permissions for these API operations, AWS Directory Service defines a set of actions that you can specify in a policy. Note that performing an API operation can require permissions for more than one action.

The following are the basic policy elements:

• Resource – In a policy, you use an Amazon Resource Name (ARN) to identify the resource to which the policy applies. For AWS Directory Service resources, you always use the wildcard character (*) in IAM policies. For more information, see AWS Directory Service resources and operations.

• Action – You use action keywords to identify resource operations that you want to allow or deny. For example, the ds:DescribeDirectories permission allows the user permissions to perform the AWS Directory Service DescribeDirectories operation.

• Effect – You specify the effect when the user requests the specific action. This can be either allow or deny. If you don't explicitly grant access to (allow) a resource, access is implicitly denied. You can also explicitly deny access to a resource, which you might do to make sure that a user cannot access it, even if a different policy grants access.

• Principal – In identity-based policies (IAM policies), the user that the policy is attached to is the implicit principal. For resource-based policies, you specify the user, account, service, or other entity that you want to receive permissions (applies to resource-based policies only). AWS Directory Service doesn't support resource-based policies.

To learn more about IAM policy syntax and descriptions, see IAM JSON policy reference in the IAM User Guide.

For a table showing all of the AWS Directory Service API actions and the resources that they apply to, see AWS Directory Service API permissions: Actions, resources, and conditions reference.

Specifying conditions in a policy

When you grant permissions, you can use the access policy language to specify the conditions when a policy should take effect. For example, you might want a policy to be applied only after a specific date. For more information about specifying conditions in a policy language, see Condition in the IAM User Guide.

To express conditions, you use predefined condition keys. There are no condition keys specific to AWS Directory Service. However, there are AWS condition keys that you can use as appropriate. For a complete list of AWS keys, see Available global condition keys in the IAM User Guide.