How Amazon EC2 Auto Scaling works with IAM

Before you use IAM to manage access to Amazon EC2 Auto Scaling, you should understand what IAM features are available to use with Amazon EC2 Auto Scaling. To get a high-level view of how Amazon EC2 Auto Scaling and other Amazon Web Services work with IAM, see Amazon Web Services that work with IAM in the IAM User Guide.

Amazon EC2 Auto Scaling identity-based policies

With IAM identity-based policies, you can specify allowed or denied actions and resources, and the conditions under which actions are allowed or denied. Amazon EC2 Auto Scaling supports specific actions, resources, and condition keys. To learn about all of the elements that you use in a JSON policy, see IAM JSON policy elements reference in the IAM User Guide.

Actions

Administrators can use AWS JSON policies to specify who has access to what. That is, which principal can perform actions on what resources, and under what conditions.

The Action element of a JSON policy describes the actions that you can use to allow or deny access in a policy. Policy actions usually have the same name as the associated AWS API operation. There are some exceptions, such as permission-only actions that don't have a matching API operation. There are also some operations that require multiple actions in a policy. These additional actions are called dependent actions.

Include actions in a policy to grant permissions to perform the associated operation.

Policy actions in Amazon EC2 Auto Scaling use the following prefix before the action: autoscaling:. Policy statements must include either an Action or NotAction element. Amazon EC2 Auto Scaling defines its own set of actions that describe tasks that you can perform with this service.

To specify multiple actions in a single statement, separate them with commas as shown in the following example.

"Action": [
      "autoscaling:CreateAutoScalingGroup",
      "autoscaling:UpdateAutoScalingGroup"

You can specify multiple actions using wildcards (*). For example, to specify all actions that begin with the word Describe, include the following action.

"Action": "autoscaling:Describe*"

To see a list of Amazon EC2 Auto Scaling actions, see Actions in the Amazon EC2 Auto Scaling API Reference.

Resources

Administrators can use AWS JSON policies to specify who has access to what. That is, which principal can perform actions on what resources, and under what conditions.

The Resource JSON policy element specifies the object or objects to which the action applies. Statements must include either a Resource or a NotResource element. As a best practice, specify a resource using its Amazon Resource Name (ARN). You can do this for actions that support a specific resource type, known as resource-level permissions.

For actions that don't support resource-level permissions, such as listing operations, use a wildcard (*) to indicate that the statement applies to all resources.

"Resource": "*"

You can restrict access to specific Auto Scaling groups and launch configurations by using their ARNs to identify the resource that the IAM policy applies to. For more information about the format of ARNs, see Amazon Resource Names (ARNs) in the AWS General Reference.

An Auto Scaling group has the following ARN.

"Resource": "arn:aws:autoscaling:region:123456789012:autoScalingGroup:uuid:autoScalingGroupName/asg-name"

A launch configuration has the following ARN.

"Resource": "arn:aws:autoscaling:region:123456789012:launchConfiguration:uuid:launchConfigurationName/lc-name"

To specify an Auto Scaling group with the CreateAutoScalingGroup action, you must replace the UUID with * as shown in the following.

"Resource": "arn:aws:autoscaling:region:123456789012:autoScalingGroup:*:autoScalingGroupName/asg-name"

To specify a launch configuration with the CreateLaunchConfiguration action, you must replace the UUID with * as shown in the following.

"Resource": "arn:aws:autoscaling:region:123456789012:launchConfiguration:*:launchConfigurationName/lc-name"

Not all Amazon EC2 Auto Scaling actions support resource-level permissions. For actions that don't support resource-level permissions, you must use "*" as the resource.

The following Amazon EC2 Auto Scaling actions do not support resource-level permissions.

To learn with which actions you can specify the ARN of each resource, see Actions, resources, and condition keys for Amazon EC2 Auto Scaling in the IAM User Guide.

Condition keys

Administrators can use AWS JSON policies to specify who has access to what. That is, which principal can perform actions on what resources, and under what conditions.

The Condition element (or Condition block) lets you specify conditions in which a statement is in effect. The Condition element is optional. You can create conditional expressions that use condition operators, such as equals or less than, to match the condition in the policy with values in the request.

If you specify multiple Condition elements in a statement, or multiple keys in a single Condition element, AWS evaluates them using a logical AND operation. If you specify multiple values for a single condition key, AWS evaluates the condition using a logical OR operation. All of the conditions must be met before the statement's permissions are granted.

You can also use placeholder variables when you specify conditions. For example, you can grant an IAM user permission to access a resource only if it is tagged with their IAM user name. For more information, see IAM policy elements: variables and tags in the IAM User Guide.

AWS supports global condition keys and service-specific condition keys. To see all AWS global condition keys, see AWS global condition context keys in the IAM User Guide.

Amazon EC2 Auto Scaling defines its own set of condition keys and also supports using some global condition keys. To see all AWS global condition keys, see AWS global condition context keys in the IAM User Guide.

The following condition keys are specific to Amazon EC2 Auto Scaling:

To learn with which actions and resources you can use a condition key, see Actions, resources, and condition keys for Amazon EC2 Auto Scaling in the IAM User Guide.

Amazon EC2 Auto Scaling resource-based policies

Other Amazon Web Services, such as Amazon Simple Storage Service, support resource-based permissions policies. For example, you can attach a permissions policy to an S3 bucket to manage access permissions to that bucket.

Amazon EC2 Auto Scaling does not support resource-based policies.

Access Control Lists (ACLs)

Amazon EC2 Auto Scaling does not support Access Control Lists (ACLs).

Authorization based on Amazon EC2 Auto Scaling tags

You can apply tag-based, resource-level permissions in the identity-based policies that you create for Amazon EC2 Auto Scaling. This gives you better control over which resources a user can create, modify, use, or delete.

To use tags with IAM policies, you provide tag information in the condition element of a policy using the following condition keys:

To see examples of identity-based policies based on tags, see Amazon EC2 Auto Scaling identity-based policy examples.

For more information, see Tagging Auto Scaling groups and instances.

Amazon EC2 Auto Scaling IAM roles

An IAM role is an entity within your AWS account that has specific permissions.

Using temporary credentials with Amazon EC2 Auto Scaling

You can use temporary credentials to sign in with federation, assume an IAM role, or to assume a cross-account role. You obtain temporary security credentials by calling AWS STS API operations such as AssumeRole or GetFederationToken.

Amazon EC2 Auto Scaling supports using temporary credentials.

Service-linked roles

Service-linked roles allow Amazon Web Services to access resources in other services to complete an action on your behalf. Service-linked roles appear in your IAM account and are owned by the service. An IAM administrator can view but not edit the permissions for service-linked roles.

Amazon EC2 Auto Scaling supports service-linked roles. For details about creating or managing Amazon EC2 Auto Scaling service-linked roles, see Service-linked roles for Amazon EC2 Auto Scaling.

Service roles

This feature allows a service to assume a service role on your behalf. This role allows the service to access resources in other services to complete an action on your behalf. An IAM administrator can change the permissions for this role. However, doing so might break the functionality of the service.

Amazon EC2 Auto Scaling supports service roles for lifecycle hook notifications. For more information, see Amazon EC2 Auto Scaling lifecycle hooks.

Choosing an IAM role in Amazon EC2 Auto Scaling

If you have previously created an IAM role that your applications running on Amazon EC2 can assume, you can choose this role when you create a launch template or launch configuration. Amazon EC2 Auto Scaling provides you with a list of roles to choose from. When creating these roles, it's important to associate least privilege IAM policies that restrict access to the specific API calls that the application requires. For more information, see IAM role for applications that run on Amazon EC2 instances.

Learn more about IAM permission policies

Use the following topics to learn more about creating IAM permission policies to control who can or cannot use specific API actions.