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AWS Identity and Access Management
API Reference (API Version 2010-05-08)

SimulateCustomPolicy

Simulate how a set of IAM policies and optionally a resource-based policy works with a list of API actions and AWS resources to determine the policies' effective permissions. The policies are provided as strings.

The simulation does not perform the API actions; it only checks the authorization to determine if the simulated policies allow or deny the actions.

If you want to simulate existing policies attached to an IAM user, group, or role, use SimulatePrincipalPolicy instead.

Context keys are variables maintained by AWS and its services that provide details about the context of an API query request. You can use the Condition element of an IAM policy to evaluate context keys. To get the list of context keys that the policies require for correct simulation, use GetContextKeysForCustomPolicy.

If the output is long, you can use MaxItems and Marker parameters to paginate the results.

Request Parameters

For information about the parameters that are common to all actions, see Common Parameters.

ActionNames.member.N

A list of names of API actions to evaluate in the simulation. Each action is evaluated against each resource. Each action must include the service identifier, such as iam:CreateUser.

Type: array of Strings

Length Constraints: Minimum length of 3. Maximum length of 128.

Required: Yes

CallerArn

The ARN of the IAM user that you want to use as the simulated caller of the APIs. CallerArn is required if you include a ResourcePolicy so that the policy's Principal element has a value to use in evaluating the policy.

You can specify only the ARN of an IAM user. You cannot specify the ARN of an assumed role, federated user, or a service principal.

Type: String

Length Constraints: Minimum length of 1. Maximum length of 2048.

Required: No

ContextEntries.member.N

A list of context keys and corresponding values for the simulation to use. Whenever a context key is evaluated in one of the simulated IAM permission policies, the corresponding value is supplied.

Type: array of ContextEntry objects

Required: No

Marker

Use this parameter only when paginating results and only after you receive a response indicating that the results are truncated. Set it to the value of the Marker element in the response that you received to indicate where the next call should start.

Type: String

Length Constraints: Minimum length of 1. Maximum length of 320.

Pattern: [\u0020-\u00FF]+

Required: No

MaxItems

Use this only when paginating results to indicate the maximum number of items you want in the response. If additional items exist beyond the maximum you specify, the IsTruncated response element is true.

This parameter is optional. If you do not include it, it defaults to 100. Note that IAM might return fewer results, even when there are more results available. In that case, the IsTruncated response element returns true and Marker contains a value to include in the subsequent call that tells the service where to continue from.

Type: Integer

Valid Range: Minimum value of 1. Maximum value of 1000.

Required: No

PolicyInputList.member.N

A list of policy documents to include in the simulation. Each document is specified as a string containing the complete, valid JSON text of an IAM policy. Do not include any resource-based policies in this parameter. Any resource-based policy must be submitted with the ResourcePolicy parameter. The policies cannot be "scope-down" policies, such as you could include in a call to GetFederationToken or one of the AssumeRole APIs to restrict what a user can do while using the temporary credentials.

The regex pattern used to validate this parameter is a string of characters consisting of any printable ASCII character ranging from the space character (\u0020) through end of the ASCII character range (\u00FF). It also includes the special characters tab (\u0009), line feed (\u000A), and carriage return (\u000D).

Type: array of Strings

Length Constraints: Minimum length of 1. Maximum length of 131072.

Pattern: [\u0009\u000A\u000D\u0020-\u00FF]+

Required: Yes

ResourceArns.member.N

A list of ARNs of AWS resources to include in the simulation. If this parameter is not provided then the value defaults to * (all resources). Each API in the ActionNames parameter is evaluated for each resource in this list. The simulation determines the access result (allowed or denied) of each combination and reports it in the response.

The simulation does not automatically retrieve policies for the specified resources. If you want to include a resource policy in the simulation, then you must include the policy as a string in the ResourcePolicy parameter.

If you include a ResourcePolicy, then it must be applicable to all of the resources included in the simulation or you receive an invalid input error.

For more information about ARNs, see Amazon Resource Names (ARNs) and AWS Service Namespaces in the AWS General Reference.

Type: array of Strings

Length Constraints: Minimum length of 1. Maximum length of 2048.

Required: No

ResourceHandlingOption

Specifies the type of simulation to run. Different APIs that support resource-based policies require different combinations of resources. By specifying the type of simulation to run, you enable the policy simulator to enforce the presence of the required resources to ensure reliable simulation results. If your simulation does not match one of the following scenarios, then you can omit this parameter. The following list shows each of the supported scenario values and the resources that you must define to run the simulation.

Each of the EC2 scenarios requires that you specify instance, image, and security-group resources. If your scenario includes an EBS volume, then you must specify that volume as a resource. If the EC2 scenario includes VPC, then you must supply the network-interface resource. If it includes an IP subnet, then you must specify the subnet resource. For more information on the EC2 scenario options, see Supported Platforms in the AWS EC2 User Guide.

  • EC2-Classic-InstanceStore

    instance, image, security-group

  • EC2-Classic-EBS

    instance, image, security-group, volume

  • EC2-VPC-InstanceStore

    instance, image, security-group, network-interface

  • EC2-VPC-InstanceStore-Subnet

    instance, image, security-group, network-interface, subnet

  • EC2-VPC-EBS

    instance, image, security-group, network-interface, volume

  • EC2-VPC-EBS-Subnet

    instance, image, security-group, network-interface, subnet, volume

Type: String

Length Constraints: Minimum length of 1. Maximum length of 64.

Required: No

ResourceOwner

An AWS account ID that specifies the owner of any simulated resource that does not identify its owner in the resource ARN, such as an S3 bucket or object. If ResourceOwner is specified, it is also used as the account owner of any ResourcePolicy included in the simulation. If the ResourceOwner parameter is not specified, then the owner of the resources and the resource policy defaults to the account of the identity provided in CallerArn. This parameter is required only if you specify a resource-based policy and account that owns the resource is different from the account that owns the simulated calling user CallerArn.

Type: String

Length Constraints: Minimum length of 1. Maximum length of 2048.

Required: No

ResourcePolicy

A resource-based policy to include in the simulation provided as a string. Each resource in the simulation is treated as if it had this policy attached. You can include only one resource-based policy in a simulation.

The regex pattern used to validate this parameter is a string of characters consisting of any printable ASCII character ranging from the space character (\u0020) through end of the ASCII character range (\u00FF). It also includes the special characters tab (\u0009), line feed (\u000A), and carriage return (\u000D).

Type: String

Length Constraints: Minimum length of 1. Maximum length of 131072.

Pattern: [\u0009\u000A\u000D\u0020-\u00FF]+

Required: No

Response Elements

The following elements are returned by the service.

EvaluationResults.member.N

The results of the simulation.

Type: array of EvaluationResult objects

IsTruncated

A flag that indicates whether there are more items to return. If your results were truncated, you can make a subsequent pagination request using the Marker request parameter to retrieve more items. Note that IAM might return fewer than the MaxItems number of results even when there are more results available. We recommend that you check IsTruncated after every call to ensure that you receive all of your results.

Type: Boolean

Marker

When IsTruncated is true, this element is present and contains the value to use for the Marker parameter in a subsequent pagination request.

Type: String

Length Constraints: Minimum length of 1. Maximum length of 320.

Pattern: [\u0020-\u00FF]+

Errors

For information about the errors that are common to all actions, see Common Errors.

InvalidInput

The request was rejected because an invalid or out-of-range value was supplied for an input parameter.

HTTP Status Code: 400

PolicyEvaluation

The request failed because a provided policy could not be successfully evaluated. An additional detail message indicates the source of the failure.

HTTP Status Code: 500

Example

Example

This example specifies a policy by string and supplies a ContextEntry to use for the context key that the policy references. Note that all parameters are shown in unencoded form here for clarity but must be URL encoded to be included as a part of a real HTML request. The results show that the policy allows s3:ListBucket access to the S3 bucket named teambucket.

Sample Request


https://iam.amazonaws.com/Action=SimulateCustomPolicy
&ActionNames.member.1=s3:ListBucket
&ResourceArns.member.1=arn:aws:s3:::teambucket
&ContextEntries.member.1.ContextKeyName=aws:MultiFactorAuthPresent
&ContextEntries.member.1.ContextKeyType=boolean
&ContextEntries.member.1.ContextKeyValues.member.1=true
&PolicyInputList.member.1='{
  "Version":"2012-10-17",
  "Statement":{
    "Effect":"Allow",
    "Action":"s3:ListBucket",
    "Resource":"arn:aws:s3:::teambucket",
    "Condition":{
      "Bool":{"aws:MultiFactorAuthPresent":"true"}
    }
  }
}'
&Version=2010-05-08
&AUTHPARAMS

Sample Response


<SimulateCustomPolicyResponse xmlns="https://iam.amazonaws.com/doc/2010-05-08/">
  <SimulateCustomPolicyResult>
    <IsTruncated>false</IsTruncated>
    <EvaluationResults>
      <member>
        <MatchedStatements>
          <member>
            <SourcePolicyId>PolicyInputList.1</SourcePolicyId>
            <EndPosition>
              <Column>4</Column>
              <Line>11</Line>
            </EndPosition>
            <StartPosition>
              <Column>16</Column>
              <Line>4</Line>
            </StartPosition>
          </member>
        </MatchedStatements>
        <MissingContextValues/>
        <EvalResourceName>arn:aws:s3:::teambucket</EvalResourceName>
        <EvalDecision>allowed</EvalDecision>
        <EvalActionName>s3:ListBucket</EvalActionName>
      </member>
    </EvaluationResults>
  </SimulateCustomPolicyResult>
  <ResponseMetadata>
    <RequestId>1cdb5b0a-4c15-11e5-b121-bd8c7EXAMPLE</RequestId>
  </ResponseMetadata>
</SimulateCustomPolicyResponse>