STS / Client / assume_role_with_web_identity

assume_role_with_web_identity#

STS.Client.assume_role_with_web_identity(**kwargs)#

Returns a set of temporary security credentials for users who have been authenticated in a mobile or web application with a web identity provider. Example providers include the OAuth 2.0 providers Login with Amazon and Facebook, or any OpenID Connect-compatible identity provider such as Google or Amazon Cognito federated identities.

Note

For mobile applications, we recommend that you use Amazon Cognito. You can use Amazon Cognito with the Amazon Web Services SDK for iOS Developer Guide and the Amazon Web Services SDK for Android Developer Guide to uniquely identify a user. You can also supply the user with a consistent identity throughout the lifetime of an application.

To learn more about Amazon Cognito, see Amazon Cognito identity pools in Amazon Cognito Developer Guide.

Calling AssumeRoleWithWebIdentity does not require the use of Amazon Web Services security credentials. Therefore, you can distribute an application (for example, on mobile devices) that requests temporary security credentials without including long-term Amazon Web Services credentials in the application. You also don’t need to deploy server-based proxy services that use long-term Amazon Web Services credentials. Instead, the identity of the caller is validated by using a token from the web identity provider. For a comparison of AssumeRoleWithWebIdentity with the other API operations that produce temporary credentials, see Requesting Temporary Security Credentials and Compare STS credentials in the IAM User Guide.

The temporary security credentials returned by this API consist of an access key ID, a secret access key, and a security token. Applications can use these temporary security credentials to sign calls to Amazon Web Services service API operations.

Session Duration

By default, the temporary security credentials created by AssumeRoleWithWebIdentity last for one hour. However, you can use the optional DurationSeconds parameter to specify the duration of your session. You can provide a value from 900 seconds (15 minutes) up to the maximum session duration setting for the role. This setting can have a value from 1 hour to 12 hours. To learn how to view the maximum value for your role, see Update the maximum session duration for a role in the IAM User Guide. The maximum session duration limit applies when you use the AssumeRole* API operations or the assume-role* CLI commands. However the limit does not apply when you use those operations to create a console URL. For more information, see Using IAM Roles in the IAM User Guide.

Permissions

The temporary security credentials created by AssumeRoleWithWebIdentity can be used to make API calls to any Amazon Web Services service with the following exception: you cannot call the STS GetFederationToken or GetSessionToken API operations.

(Optional) You can pass inline or managed session policies to this operation. You can pass a single JSON policy document to use as an inline session policy. You can also specify up to 10 managed policy Amazon Resource Names (ARNs) to use as managed session policies. The plaintext that you use for both inline and managed session policies can’t exceed 2,048 characters. Passing policies to this operation returns new temporary credentials. The resulting session’s permissions are the intersection of the role’s identity-based policy and the session policies. You can use the role’s temporary credentials in subsequent Amazon Web Services API calls to access resources in the account that owns the role. You cannot use session policies to grant more permissions than those allowed by the identity-based policy of the role that is being assumed. For more information, see Session Policies in the IAM User Guide.

Tags

(Optional) You can configure your IdP to pass attributes into your web identity token as session tags. Each session tag consists of a key name and an associated value. For more information about session tags, see Passing Session Tags in STS in the IAM User Guide.

You can pass up to 50 session tags. The plaintext session tag keys can’t exceed 128 characters and the values can’t exceed 256 characters. For these and additional limits, see IAM and STS Character Limits in the IAM User Guide.

Note

An Amazon Web Services conversion compresses the passed inline session policy, managed policy ARNs, and session tags into a packed binary format that has a separate limit. Your request can fail for this limit even if your plaintext meets the other requirements. The PackedPolicySize response element indicates by percentage how close the policies and tags for your request are to the upper size limit.

You can pass a session tag with the same key as a tag that is attached to the role. When you do, the session tag overrides the role tag with the same key.

An administrator must grant you the permissions necessary to pass session tags. The administrator can also create granular permissions to allow you to pass only specific session tags. For more information, see Tutorial: Using Tags for Attribute-Based Access Control in the IAM User Guide.

You can set the session tags as transitive. Transitive tags persist during role chaining. For more information, see Chaining Roles with Session Tags in the IAM User Guide.

Identities

Before your application can call AssumeRoleWithWebIdentity, you must have an identity token from a supported identity provider and create a role that the application can assume. The role that your application assumes must trust the identity provider that is associated with the identity token. In other words, the identity provider must be specified in the role’s trust policy.

Warning

Calling AssumeRoleWithWebIdentity can result in an entry in your CloudTrail logs. The entry includes the Subject of the provided web identity token. We recommend that you avoid using any personally identifiable information (PII) in this field. For example, you could instead use a GUID or a pairwise identifier, as suggested in the OIDC specification.

For more information about how to use OIDC federation and the AssumeRoleWithWebIdentity API, see the following resources:

See also: AWS API Documentation

Request Syntax

response = client.assume_role_with_web_identity(
    RoleArn='string',
    RoleSessionName='string',
    WebIdentityToken='string',
    ProviderId='string',
    PolicyArns=[
        {
            'arn': 'string'
        },
    ],
    Policy='string',
    DurationSeconds=123
)
Parameters:

  • RoleArn (string) –

    [REQUIRED]

    The Amazon Resource Name (ARN) of the role that the caller is assuming.

    Note

    Additional considerations apply to Amazon Cognito identity pools that assume cross-account IAM roles. The trust policies of these roles must accept the cognito-identity.amazonaws.com service principal and must contain the cognito-identity.amazonaws.com:aud condition key to restrict role assumption to users from your intended identity pools. A policy that trusts Amazon Cognito identity pools without this condition creates a risk that a user from an unintended identity pool can assume the role. For more information, see Trust policies for IAM roles in Basic (Classic) authentication in the Amazon Cognito Developer Guide.

  • RoleSessionName (string) –

    [REQUIRED]

    An identifier for the assumed role session. Typically, you pass the name or identifier that is associated with the user who is using your application. That way, the temporary security credentials that your application will use are associated with that user. This session name is included as part of the ARN and assumed role ID in the AssumedRoleUser response element.

    For security purposes, administrators can view this field in CloudTrail logs to help identify who performed an action in Amazon Web Services. Your administrator might require that you specify your user name as the session name when you assume the role. For more information, see sts:RoleSessionName.

    The regex used to validate this parameter is a string of characters consisting of upper- and lower-case alphanumeric characters with no spaces. You can also include underscores or any of the following characters: =,.@-

  • WebIdentityToken (string) –

    [REQUIRED]

    The OAuth 2.0 access token or OpenID Connect ID token that is provided by the identity provider. Your application must get this token by authenticating the user who is using your application with a web identity provider before the application makes an AssumeRoleWithWebIdentity call. Timestamps in the token must be formatted as either an integer or a long integer. Only tokens with RSA algorithms (RS256) are supported.

  • ProviderId (string) –

    The fully qualified host component of the domain name of the OAuth 2.0 identity provider. Do not specify this value for an OpenID Connect identity provider.

    Currently www.amazon.com and graph.facebook.com are the only supported identity providers for OAuth 2.0 access tokens. Do not include URL schemes and port numbers.

    Do not specify this value for OpenID Connect ID tokens.

  • PolicyArns (list) –

    The Amazon Resource Names (ARNs) of the IAM managed policies that you want to use as managed session policies. The policies must exist in the same account as the role.

    This parameter is optional. You can provide up to 10 managed policy ARNs. However, the plaintext that you use for both inline and managed session policies can’t exceed 2,048 characters. For more information about ARNs, see Amazon Resource Names (ARNs) and Amazon Web Services Service Namespaces in the Amazon Web Services General Reference.

    Note

    An Amazon Web Services conversion compresses the passed inline session policy, managed policy ARNs, and session tags into a packed binary format that has a separate limit. Your request can fail for this limit even if your plaintext meets the other requirements. The PackedPolicySize response element indicates by percentage how close the policies and tags for your request are to the upper size limit.

    Passing policies to this operation returns new temporary credentials. The resulting session’s permissions are the intersection of the role’s identity-based policy and the session policies. You can use the role’s temporary credentials in subsequent Amazon Web Services API calls to access resources in the account that owns the role. You cannot use session policies to grant more permissions than those allowed by the identity-based policy of the role that is being assumed. For more information, see Session Policies in the IAM User Guide.

    • (dict) –

      A reference to the IAM managed policy that is passed as a session policy for a role session or a federated user session.

  • Policy (string) –

    An IAM policy in JSON format that you want to use as an inline session policy.

    This parameter is optional. Passing policies to this operation returns new temporary credentials. The resulting session’s permissions are the intersection of the role’s identity-based policy and the session policies. You can use the role’s temporary credentials in subsequent Amazon Web Services API calls to access resources in the account that owns the role. You cannot use session policies to grant more permissions than those allowed by the identity-based policy of the role that is being assumed. For more information, see Session Policies in the IAM User Guide.

    The plaintext that you use for both inline and managed session policies can’t exceed 2,048 characters. The JSON policy characters can be any ASCII character from the space character to the end of the valid character list (u0020 through u00FF). It can also include the tab (u0009), linefeed (u000A), and carriage return (u000D) characters.

    For more information about role session permissions, see Session policies.

    Note

    An Amazon Web Services conversion compresses the passed inline session policy, managed policy ARNs, and session tags into a packed binary format that has a separate limit. Your request can fail for this limit even if your plaintext meets the other requirements. The PackedPolicySize response element indicates by percentage how close the policies and tags for your request are to the upper size limit.

  • DurationSeconds (integer) –

    The duration, in seconds, of the role session. The value can range from 900 seconds (15 minutes) up to the maximum session duration setting for the role. This setting can have a value from 1 hour to 12 hours. If you specify a value higher than this setting, the operation fails. For example, if you specify a session duration of 12 hours, but your administrator set the maximum session duration to 6 hours, your operation fails. To learn how to view the maximum value for your role, see View the Maximum Session Duration Setting for a Role in the IAM User Guide.

    By default, the value is set to 3600 seconds.

    Note

    The DurationSeconds parameter is separate from the duration of a console session that you might request using the returned credentials. The request to the federation endpoint for a console sign-in token takes a SessionDuration parameter that specifies the maximum length of the console session. For more information, see Creating a URL that Enables Federated Users to Access the Amazon Web Services Management Console in the IAM User Guide.

Return type:

dict

Returns:

Response Syntax

{
    'Credentials': {
        'AccessKeyId': 'string',
        'SecretAccessKey': 'string',
        'SessionToken': 'string',
        'Expiration': datetime(2015, 1, 1)
    },
    'SubjectFromWebIdentityToken': 'string',
    'AssumedRoleUser': {
        'AssumedRoleId': 'string',
        'Arn': 'string'
    },
    'PackedPolicySize': 123,
    'Provider': 'string',
    'Audience': 'string',
    'SourceIdentity': 'string'
}

Response Structure

  • (dict) –

    Contains the response to a successful AssumeRoleWithWebIdentity request, including temporary Amazon Web Services credentials that can be used to make Amazon Web Services requests.

    • Credentials (dict) –

      The temporary security credentials, which include an access key ID, a secret access key, and a security token.

      Note

      The size of the security token that STS API operations return is not fixed. We strongly recommend that you make no assumptions about the maximum size.

      • AccessKeyId (string) –

        The access key ID that identifies the temporary security credentials.

      • SecretAccessKey (string) –

        The secret access key that can be used to sign requests.

      • SessionToken (string) –

        The token that users must pass to the service API to use the temporary credentials.

      • Expiration (datetime) –

        The date on which the current credentials expire.

    • SubjectFromWebIdentityToken (string) –

      The unique user identifier that is returned by the identity provider. This identifier is associated with the WebIdentityToken that was submitted with the AssumeRoleWithWebIdentity call. The identifier is typically unique to the user and the application that acquired the WebIdentityToken (pairwise identifier). For OpenID Connect ID tokens, this field contains the value returned by the identity provider as the token’s sub (Subject) claim.

    • AssumedRoleUser (dict) –

      The Amazon Resource Name (ARN) and the assumed role ID, which are identifiers that you can use to refer to the resulting temporary security credentials. For example, you can reference these credentials as a principal in a resource-based policy by using the ARN or assumed role ID. The ARN and ID include the RoleSessionName that you specified when you called AssumeRole.

      • AssumedRoleId (string) –

        A unique identifier that contains the role ID and the role session name of the role that is being assumed. The role ID is generated by Amazon Web Services when the role is created.

      • Arn (string) –

        The ARN of the temporary security credentials that are returned from the AssumeRole action. For more information about ARNs and how to use them in policies, see IAM Identifiers in the IAM User Guide.

    • PackedPolicySize (integer) –

      A percentage value that indicates the packed size of the session policies and session tags combined passed in the request. The request fails if the packed size is greater than 100 percent, which means the policies and tags exceeded the allowed space.

    • Provider (string) –

      The issuing authority of the web identity token presented. For OpenID Connect ID tokens, this contains the value of the iss field. For OAuth 2.0 access tokens, this contains the value of the ProviderId parameter that was passed in the AssumeRoleWithWebIdentity request.

    • Audience (string) –

      The intended audience (also known as client ID) of the web identity token. This is traditionally the client identifier issued to the application that requested the web identity token.

    • SourceIdentity (string) –

      The value of the source identity that is returned in the JSON web token (JWT) from the identity provider.

      You can require users to set a source identity value when they assume a role. You do this by using the sts:SourceIdentity condition key in a role trust policy. That way, actions that are taken with the role are associated with that user. After the source identity is set, the value cannot be changed. It is present in the request for all actions that are taken by the role and persists across chained role sessions. You can configure your identity provider to use an attribute associated with your users, like user name or email, as the source identity when calling AssumeRoleWithWebIdentity. You do this by adding a claim to the JSON web token. To learn more about OIDC tokens and claims, see Using Tokens with User Pools in the Amazon Cognito Developer Guide. For more information about using source identity, see Monitor and control actions taken with assumed roles in the IAM User Guide.

      The regex used to validate this parameter is a string of characters consisting of upper- and lower-case alphanumeric characters with no spaces. You can also include underscores or any of the following characters: =,.@-

Exceptions

  • STS.Client.exceptions.MalformedPolicyDocumentException

  • STS.Client.exceptions.PackedPolicyTooLargeException

  • STS.Client.exceptions.IDPRejectedClaimException

  • STS.Client.exceptions.IDPCommunicationErrorException

  • STS.Client.exceptions.InvalidIdentityTokenException

  • STS.Client.exceptions.ExpiredTokenException

  • STS.Client.exceptions.RegionDisabledException

Examples

response = client.assume_role_with_web_identity(
    DurationSeconds=3600,
    Policy='{"Version":"2012-10-17","Statement":[{"Sid":"Stmt1","Effect":"Allow","Action":"s3:ListAllMyBuckets","Resource":"*"}]}',
    ProviderId='www.amazon.com',
    RoleArn='arn:aws:iam::123456789012:role/FederatedWebIdentityRole',
    RoleSessionName='app1',
    WebIdentityToken='Atza%7CIQEBLjAsAhRFiXuWpUXuRvQ9PZL3GMFcYevydwIUFAHZwXZXXXXXXXXJnrulxKDHwy87oGKPznh0D6bEQZTSCzyoCtL_8S07pLpr0zMbn6w1lfVZKNTBdDansFBmtGnIsIapjI6xKR02Yc_2bQ8LZbUXSGm6Ry6_BG7PrtLZtj_dfCTj92xNGed-CrKqjG7nPBjNIL016GGvuS5gSvPRUxWES3VYfm1wl7WTI7jn-Pcb6M-buCgHhFOzTQxod27L9CqnOLio7N3gZAGpsp6n1-AJBOCJckcyXe2c6uD0srOJeZlKUm2eTDVMf8IehDVI0r1QOnTV6KzzAI3OY87Vd_cVMQ',
)

print(response)

Expected Output:

{
    'AssumedRoleUser': {
        'Arn': 'arn:aws:sts::123456789012:assumed-role/FederatedWebIdentityRole/app1',
        'AssumedRoleId': 'AROACLKWSDQRAOEXAMPLE:app1',
    },
    'Audience': 'client.5498841531868486423.1548@apps.example.com',
    'Credentials': {
        'AccessKeyId': 'AKIAIOSFODNN7EXAMPLE',
        'Expiration': datetime(2014, 10, 24, 23, 0, 23, 4, 297, 0),
        'SecretAccessKey': 'wJalrXUtnFEMI/K7MDENG/bPxRfiCYzEXAMPLEKEY',
        'SessionToken': 'AQoDYXdzEE0a8ANXXXXXXXXNO1ewxE5TijQyp+IEXAMPLE',
    },
    'PackedPolicySize': 123,
    'Provider': 'www.amazon.com',
    'SubjectFromWebIdentityToken': 'amzn1.account.AF6RHO7KZU5XRVQJGXK6HEXAMPLE',
    'ResponseMetadata': {
        '...': '...',
    },
}