Use VPC endpoint policies for private APIs in API Gateway - Amazon API Gateway
VPC endpoint policy considerationsVPC endpoint policy examplesExample 1: VPC endpoint policy granting access to two APIsExample 2: VPC endpoint policy granting access to GET methodsExample 3: VPC endpoint policy granting a specific user access to a specific APIExample 4: VPC endpoint policy granting users access to a specific custom domain name and every API mapped to the domainExample 5: VPC endpoint policy granting or denying access to specific APIs and domain resources

Use VPC endpoint policies for private APIs in API Gateway

To improve the security of your private API, you can create a VPC endpoint policy. A VPC endpoint policy is an IAM resource policy that you attach to a VPC endpoint. For more information, see Controlling Access to Services with VPC Endpoints.

You might want to create a VPC endpoint policy to do the following tasks.

  • Allow only certain organizations or resources to access your VPC endpoint and invoke your API.

  • Use a single policy and avoid session-based or role-based policies to control traffic to your API.

  • Tighten the security perimeter of your application while migrating from on premises to AWS.

VPC endpoint policy considerations

The following are considerations for your VPC endpoint policy.

  • The identity of the invoker is evaluated based on the Authorization header value. Depending on your authorizationType, this may lead to an 403 IncompleteSignatureException or an 403 InvalidSignatureException error. The following table shows the Authorization header values for each authorizationType.

    authorizationType

    Authorizationheader evaluated?

    Allowed Authorization header values
    NONE with the default full access policy No Not passed
    NONE with a custom access policy Yes Must be a valid SigV4 value
    IAM Yes Must be a valid SigV4 value
    CUSTOM or COGNITO_USER_POOLS No Not passed

  • If a policy restricts access to a specific IAM principal, such as arn:aws:iam::account-id:role/developer, you must set the authorizationType of your API's method to AWS_IAM or NONE. For more instructions on how to set the authorizationType for a method, see Methods for REST APIs in API Gateway.

  • VPC endpoint policies can be used together with API Gateway resource policies. The API Gateway resource policy specifies which principals can access the API. The endpoint policy specifies who can access the VPC and which APIs can be called from the VPC endpoint. Your private API needs a resource policy but you don't need to create a custom VPC endpoint policy.

VPC endpoint policy examples

You can create policies for Amazon Virtual Private Cloud endpoints for Amazon API Gateway in which you can specify the following.

  • The principal that can perform actions.

  • The actions that can be performed.

  • The resources that can have actions performed on them.

To attach the policy to the VPC endpoint, you'll need to use the VPC console. For more information, see Controlling Access to Services with VPC Endpoints.

Example 1: VPC endpoint policy granting access to two APIs

The following example policy grants access to only two specific APIs via the VPC endpoint that the policy is attached to.

{
    "Statement": [
        {
            "Principal": "*",
            "Action": [
                "execute-api:Invoke"
            ],
            "Effect": "Allow",
            "Resource": [
                "arn:aws:execute-api:us-east-1:123412341234:a1b2c3d4e5/*",
                "arn:aws:execute-api:us-east-1:123412341234:aaaaa11111/*"
            ]
        }
    ]
}

Example 2: VPC endpoint policy granting access to GET methods

The following example policy grants users access to GET methods for a specific API via the VPC endpoint that the policy is attached to.

{
    "Statement": [
        {
            "Principal": "*",
            "Action": [
                "execute-api:Invoke"
            ],
            "Effect": "Allow",
            "Resource": [
                "arn:aws:execute-api:us-east-1:123412341234:a1b2c3d4e5/stageName/GET/*"
            ]
        }
    ]
}

Example 3: VPC endpoint policy granting a specific user access to a specific API

The following example policy grants a specific user access to a specific API via the VPC endpoint that the policy is attached to.

In this case, because the policy restricts access to specific IAM principals, you must set the authorizationType of the method to AWS_IAM or NONE.

{
    "Statement": [
        {
            "Principal": {
                "AWS": [
                    "arn:aws:iam::123412341234:user/MyUser"
                ]
            },
            "Action": [
                "execute-api:Invoke"
            ],
            "Effect": "Allow",
            "Resource": [
                "arn:aws:execute-api:us-east-1:123412341234:a1b2c3d4e5/*"
            ]
        }
    ]
}

Example 4: VPC endpoint policy granting users access to a specific custom domain name and every API mapped to the domain

The following example policy grants users access to a specific custom domain name for private APIs via the VPC endpoint that the policy is attached to. With this policy, as long as a user has created a domain name access association between the VPC endpoint and the custom domain name and is granted access to invoke the custom domain name and any private API's mapped to the custom domain name, the user can invoke any APIs mapped to this custom domain name. For more information, see Custom domain names for private APIs in API Gateway.

{
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "AWS": "*"
      },
      "Action": "execute-api:Invoke",
      "Resource": [
        "*"
      ],
       "Condition": {
        "ArnEquals": {
          "execute-api:viaDomainArn": "arn:aws:execute-api:us-west-2:111122223333:/domainnames/private.test.com+f4g5h6",
        }
      }
    }
  ]
}

Example 5: VPC endpoint policy granting or denying access to specific APIs and domain resources

The following example policy grants users access to specific APIs and domain resources. With this policy, as long as a user has created a domain name access association between the VPC endpoint and the custom domain name and is granted access to invoke the custom domain name and any private API's mapped to the custom domain name, the user can invoke allowed private APIs and domain resources. For more information, see Custom domain names for private APIs in API Gateway.

{
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "AWS": "*"
      },
      "Action": "execute-api:Invoke",
      "Resource": [
        "arn:aws:execute-api:us-west-2:111122223333:/domainnames/private.test.com+f4g5h6",
        "arn:aws:execute-api:us-west-2:111122223333:a1b2c3d4e5/*"
      ]
    },
    {
      "Effect": "Deny",
      "Principal": {
        "AWS": "*"
      },
      "Action": "execute-api:Invoke",
      "Resource": [
        "arn:aws:execute-api:us-west-2:111122223333:a1b2c3d4e5/admin/*",
        "arn:aws:execute-api:us-west-2:111122223333:bcd123455/*"
      ]
    }
  ]
}