How Amazon API Gateway works with IAM - Amazon API Gateway

How Amazon API Gateway works with IAM

Before you use IAM to manage access to API Gateway, you should understand what IAM features are available to use with API Gateway. To get a high-level view of how API Gateway and other AWS services work with IAM, see AWS Services That Work with IAM in the IAM User Guide.

API Gateway identity-based policies

With IAM identity-based policies, you can specify which actions and resources are allowed or denied as well as the conditions under which actions are allowed or denied. API Gateway supports specific actions, resources, and condition keys. For information about all of the elements that you use in a JSON policy, see IAM JSON Policy Elements Reference in the IAM User Guide.

The following example shows an identity-based policy that allows a user to create or update only private REST APIs. For more examples, see Amazon API Gateway identity-based policy examples.

{ "Version": "2012-10-17", "Statement": [ { "Sid": "ScopeToPrivateApis", "Effect": "Allow", "Action": [ "apigateway:PATCH", "apigateway:POST", "apigateway:PUT" ], "Resource": [ "arn:aws:apigateway:us-east-1::/restapis", "arn:aws:apigateway:us-east-1::/restapis/??????????" ], "Condition": { "ForAllValues:StringEqualsIfExists": { "apigateway:Request/EndpointType": "PRIVATE", "apigateway:Resource/EndpointType": "PRIVATE" } } }, { "Sid": "AllowResourcePolicyUpdates", "Effect": "Allow", "Action": [ "apigateway:UpdateRestApiPolicy" ], "Resource": [ "arn:aws:apigateway:us-east-1::/restapis/*" ] } ] }

Actions

The Action element of a JSON policy describes the actions that you can use to allow or deny access in a policy.

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

The API-managing Action expression has the format apigateway:action, where action is one of the following API Gateway actions: GET, POST, PUT, DELETE, PATCH (to update resources), or *, which is all of the previous actions.

Some examples of the Action expression include:

  • apigateway:* for all API Gateway actions.

  • apigateway:GET for just the GET action in API Gateway.

To specify multiple actions in a single statement, separate them with commas as follows:

"Action": [ "apigateway:action1", "apigateway:action2"

For information about HTTP verbs to use for specific API Gateway operations, see Amazon API Gateway Version 1 API Reference (REST APIs) and Amazon API Gateway Version 2 API Reference (WebSocket and HTTP APIs).

For more information, see Amazon API Gateway identity-based policy examples.

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": "*"

API Gateway resources have the following ARN format:

arn:aws:apigateway:region::resource-path-specifier

For example, to specify a REST API with the id api-id and its sub-resources, such as authorizers in your statement, use the following ARN:

"Resource": "arn:aws:apigateway:us-east-2::/restapis/api-id/*"

To specify all REST APIs and sub-resources that belong to a specific account, use the wildcard (*):

"Resource": "arn:aws:apigateway:us-east-2::/restapis/*"

For a list of API Gateway resource types and their ARNs, see API Gateway Amazon Resource Name (ARN) reference.

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.

API Gateway defines its own set of condition keys and also supports using some global condition keys. For a list of API Gateway condition keys, see Condition Keys for Amazon API Gateway in the IAM User Guide. For information about which actions and resources you can use with a condition key, see Actions Defined by Amazon API Gateway.

For information about tagging, including tag-based access control, see Tagging your API Gateway resources.

Examples

For examples of API Gateway identity-based policies, see Amazon API Gateway identity-based policy examples.

API Gateway resource-based policies

Resource-based policies are JSON policy documents that specify what actions a specified principal can perform on the API Gateway resource and under what conditions. API Gateway supports resource-based permissions policies for REST APIs. You use resource policies to control who can invoke a REST API. For more information, see Controlling access to an API with API Gateway resource policies.

Examples

For examples of API Gateway resource-based policies, see API Gateway resource policy examples.

Authorization based on API Gateway tags

You can attach tags to API Gateway resources or pass tags in a request to API Gateway. To control access based on tags, you provide tag information in the condition element of a policy using the apigateway:ResourceTag/key-name, aws:RequestTag/key-name, or aws:TagKeys condition keys. For more information about tagging API Gateway resources, see Using tags to control access to API Gateway resources.

For an examples of identity-based policies for limiting access to a resource based on the tags on that resource, see Using tags to control access to API Gateway resources.

API Gateway IAM roles

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

Using temporary credentials with API Gateway

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.

API Gateway supports using temporary credentials.

Service-linked roles

Service-linked roles allow AWS 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.

API Gateway supports service-linked roles. For information about creating or managing API Gateway service-linked roles, see Using service-linked roles for API Gateway.

Service roles

A service can assume a service role on your behalf. A service role allows the service to access resources in other services to complete an action on your behalf. Service roles appear in your IAM account and are owned by the account, so an IAM administrator can change the permissions for this role. However, doing so might break the functionality of the service.

API Gateway supports service roles.