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Amazon CloudWatch Events
User Guide

Overview of Managing Access Permissions to Your CloudWatch Events Resources

Every AWS resource is owned by an AWS 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), 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.

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

CloudWatch Events Resources and Operations

In CloudWatch Events, the primary resource is a rule. CloudWatch Events supports other resources that can be used with the primary resource, such as events. These are referred to as subresources. These resources and subresources have unique Amazon Resource Names (ARNs) associated with them. For more information about ARNs, see Amazon Resource Names (ARN) and AWS Service Namespaces in the Amazon Web Services General Reference.

Resource TypeARN Format

Rule

arn:aws:events:region:account:rule/rule-name

All CloudWatch Events resources

arn:aws:events:*

All CloudWatch Events resources owned by the specified account in the specified region

arn:aws:events:region:account:*

Note

Most services in AWS treat a colon (:) or a forward slash (/) as the same character in ARNs. However, CloudWatch Events uses an exact match in event patterns and rules. Be sure to use the correct ARN characters when creating event patterns so that they match the ARN syntax in the event you want to match.

For example, you can indicate a specific rule (myRule) in your statement using its ARN as follows:

"Resource": "arn:aws:events:us-east-1:123456789012:rule/myRule"

You can also specify all rules that belong to a specific account by using the asterisk (*) wildcard as follows:

"Resource": "arn:aws:events:us-east-1:123456789012:rule/*"

To specify all resources, or if a specific API action does not support ARNs, use the asterisk (*) wildcard in the Resource element as follows:

"Resource": "*"

Some CloudWatch Events API actions accept multiple resources (e.g., PutTargets). To specify multiple resources in a single statement, separate their ARNs with commas, as follows:

"Resource": ["arn1", "arn2"]

CloudWatch Events provides a set of operations to work with the CloudWatch Events resources. For a list of available operations, see CloudWatch Events Permissions Reference.

Understanding Resource Ownership

The AWS account owns the resources that are created in the account, regardless of who created the resources. Specifically, the resource owner is the AWS account of the principal entity (that is, the root account, an IAM user, or an IAM role) that authenticates the resource creation request. The following examples illustrate how this works:

  • If you use the root account credentials of your AWS account to create a rule, your AWS account is the owner of the CloudWatch Events resource.

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

  • If you create an IAM role in your AWS account with permissions to create CloudWatch Events resources, anyone who can assume the role can create CloudWatch Events resources. Your AWS account, to which the role belongs, owns the CloudWatch Events 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 CloudWatch Events. 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 AWS IAM 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. CloudWatch Events supports both identity-based (IAM policies) and 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 – To grant a user permissions to view rules in the CloudWatch console, you can attach a permissions policy to a user or group that the user belongs to.

  • 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 AWS account (for example, Account B) or an AWS 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. The principal in the trust policy an also be an AWS service principal if you want to grant an AWS service permissions to assume the role.

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

The following policy allows CloudWatch Events to relay events to the streams in Amazon Kinesis streams in your account.

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "CloudWatchEventsInvocationAccess",
            "Effect": "Allow",
            "Action": [
                "kinesis:PutRecord"
            ],
            "Resource": "*"
        }
    ]
}

You can create specific IAM policies to restrict the calls and resources that users in your account have access to, and then attach those policies to IAM users. For more information about how to create IAM roles and to explore example IAM policy statements for CloudWatch Events, see Overview of Managing Access Permissions to Your CloudWatch Events Resources.

Resource-Based Policies

When a rule is triggered in CloudWatch Events, all the targets associated with the rule are invoked. Invocation means invoking the AWS Lambda functions, publishing to the Amazon SNS topics, and relaying the event to the Amazon Kinesis streams. In order to be able to make API calls against the resources you own, CloudWatch Events needs the appropriate permissions. For Lambda, Amazon SNS, and Amazon SQS resources, CloudWatch Events relies on resource-based policies. For Amazon Kinesis streams, CloudWatch Events relies on IAM roles.

For more information about how to create IAM roles and to explore example resource-based policy statements for CloudWatch Events, see Using Resource-Based Policies for CloudWatch Events.

Specifying Policy Elements: Actions, Effects, and Principals

For each CloudWatch Events resource, the service defines a set of API operations. To grant permissions for these API operations, CloudWatch Events defines a set of actions that you can specify in a policy. Some API operations can require permissions for more than one action in order to perform the API operation. For more information about resources and API operations, see CloudWatch Events Resources and Operations and CloudWatch Events Permissions Reference.

The following are the basic policy elements:

  • Resource – You use an Amazon Resource Name (ARN) to identify the resource that the policy applies to. For more information, see CloudWatch Events Resources and Operations.

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

  • Effect – You specify the effect, either allow or deny, when the user requests the specific action. 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).

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

For a table showing all of the CloudWatch Events API actions and the resources that they apply to, see CloudWatch Events Permissions 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 AWS-wide condition keys and CloudWatch Events–specific keys that you can use as appropriate. For a complete list of AWS-wide keys, see Available Keys for Conditions in the IAM User Guide. For a complete list of CloudWatch Events–specific keys, see Using IAM Policy Conditions for Fine-Grained Access Control.