Overview of managing access permissions to your MemoryDB resources - Amazon MemoryDB for Redis
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Overview of managing access permissions to your MemoryDB resources

Every Amazon resource is owned by an Amazon account, and permissions to create or access a resource are governed by permissions policies. An account administrator can attach permissions policies to IAM identities (that is, users, groups, and roles). In addition, MemoryDB for Redis also supports 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.

When granting permissions, you decide who is getting the permissions. You also decide the resources they get permissions for and the specific actions that you want to allow on those resources.

MemoryDB for Redis resources and operations

In MemoryDB for Redis, the primary resource is a cluster.

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

Note

For resource-level permissions to be effective, the resource name on the ARN string should be lower case.

Resource type ARN format

User

arn:aws:memorydb:us-east-1:123456789012:user/user1

Access Control List (ACL)

arn:aws:memorydb:us-east-1:123456789012:acl/myacl

Cluster

arn:aws:memorydb:us-east-1:123456789012:cluster/my-cluster

Snapshot

arn:aws:memorydb:us-east-1:123456789012:snapshot/my-snapshot

Parameter group

arn:aws:memorydb:us-east-1:123456789012:parametergroup/my-parameter-group

Subnet group

arn:aws:memorydb:us-east-1:123456789012:subnetgroup/my-subnet-group

MemoryDB provides a set of operations to work with MemoryDB resources. For a list of available operations, see MemoryDB for Redis Actions.

Understanding resource ownership

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

  • Suppose that you use the root account credentials of your Amazon account to create a cluster. In this case, your Amazon account is the owner of the resource. In MemoryDB, the resource is the cluster.

  • Suppose that you create an IAM user in your Amazon account and grant permissions to create a cluster to that user. In this case, the user can create a cluster. However, your Amazon account, to which the user belongs, owns the cluster resource.

  • Suppose that you create an IAM role in your Amazon account with permissions to create a cluster. In this case, anyone who can assume the role can create a cluster. Your Amazon account, to which the role belongs, owns the cluster resource.

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 MemoryDB for Redis. 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 Amazon IAM Policy Reference in the IAM User Guide.

Policies attached to an IAM identity are referred to as identity-based policies (IAM policies). Policies attached to a resource are referred to as 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. In this case, the permissions are for that user to create a MemoryDB resource, such as a cluster, parameter group, or security group.

  • 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 example, the administrator in Account A can create a role to grant cross-account permissions to another Amazon account (for example, Account B) or an Amazon service as follows:

    1. Account A administrator creates an IAM role and attaches a permissions policy to the role that grants permissions on resources in Account A.

    2. Account A administrator attaches a trust policy to the role identifying Account B as the principal who can assume the role.

    3. Account B administrator can then delegate permissions to assume the role to any users in Account B. Doing this allows users in Account B to create or access resources in Account A. In some cases, you might want to grant an Amazon service permissions to assume the role. To support this approach, the principal in the trust policy can also be an Amazon service principal.

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

The following is an example policy that allows a user to perform the DescribeClusters action for your Amazon account. MemoryDB also supports identifying specific resources using the resource ARNs for API actions. (This approach is also referred to as resource-level permissions).

{ "Version": "2012-10-17", "Statement": [{ "Sid": "DescribeClusters", "Effect": "Allow", "Action": [ "memorydb:DescribeClusters"], "Resource": resource-arn } ] }

For more information about using identity-based policies with MemoryDB, see Using identity-based policies (IAM policies) for MemoryDB for Redis. For more information about users, groups, roles, and permissions, see Identities (Users, Groups, and Roles in the IAM User Guide.

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

For each MemoryDB for Redis resource (see MemoryDB for Redis resources and operations), the service defines a set of API operations (see Actions). To grant permissions for these API operations, MemoryDB defines a set of actions that you can specify in a policy. For example, for the MemoryDB cluster resource, the following actions are defined: CreateCluster, DeleteCluster, and DescribeClusters. Performing an API operation can require permissions for more than one action.

The following are the most basic policy elements:

  • Resource – In a policy, you use an Amazon Resource Name (ARN) to identify the resource to which the policy applies. For more information, see MemoryDB for Redis resources and operations.

  • Action – You use action keywords to identify resource operations that you want to allow or deny. For example, depending on the specified Effect, the memorydb:CreateCluster permission allows or denies the user permissions to perform the MemoryDB for Redis CreateCluster 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. For example, you might do this to make sure that a user can't access a resource, 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).

To learn more about IAM policy syntax and descriptions, see Amazon IAM Policy Reference in the IAM User Guide.

For a table showing all of the MemoryDB for Redis API actions, see MemoryDB API permissions: Actions, resources, and conditions reference.

Specifying conditions in a policy

When you grant permissions, you can use the IAM 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.