Configure Workload Identity Federation with other identity providers

This guide describes how to use Workload Identity Federation with other identity providers (IdPs).

Workloads that run outside of Google Cloud might have access to existing, environment-specific credentials—for example:

• A workload might be able to obtain a SAML assertion or OpenID Connect (OIDC) token from an identity provider (IdP) that runs in the same environment.

  To authenticate to Google Cloud, you can let the workload exchange its environment-specific credentials for short-lived Google Cloud credentials by using Workload Identity Federation.

• A workload might possess an X.509 certificate. See Configure Workload Identity Federation with X.509 Certificate (Preview) for more details. SAML X.509 signing key requirements include the following:

  • An RSA public key that is wrapped in an X.509 v3 certificate.

  • Certificate validity requirements:

    • notBefore: a timestamp that is no more than 7 days in the future
    • notAfter: a timestamp that is no more than 20 years in the future

  • Recommended algorithms:

    • RSAwithSHA256 (supported key sizes (bits): 2048, 3072, 4096)
    • ECDSAwithSHA256

  A workload identity pool provider can be configured with at most three signing keys at a given time. When multiple keys exist, Google Cloud iterates through them and attempts to use each non-expired key to fulfill a token exchange request.

  As a security best practice, we strongly recommend that you don't reuse the same key pair with other services.

• A workload might possess other types of credentials.

  By combining Workload Identity Federation with a custom token broker, you can let workloads use other types of credentials to obtain short-lived Google Cloud credentials.

Using Workload Identity Federation can help you reduce the number of credentials that require rotation.

The following sections describe how you can use Workload Identity Federation with IdPs that support either OpenID Connect (OIDC) or SAML authentication protocols.

Note: If your workloads run on AWS or Azure, see Configure Workload Identity Federation with AWS or Azure instead. If you're using Active Directory Federation Services (AD FS) as IdP, see Configure Workload Identity Federation with Active Directory.

Prepare your external IdP

You only need to perform these steps once for each IdP.

Before you begin, verify that your external IdP meets the following requirements:

OIDC

• The IdP supports OpenID Connect 1.0.

• The IdP has an issuer URI.

• The IdP's OIDC metadata is provided in one of the following ways:

  • JWKS endpoints that are secured with SSL and TLS. The endpoint URLs must start with https://, and the endpoints are publicly accessible over the internet.

    Google Cloud uses these endpoints to download your IdP's key set and uses this key set to validate tokens.

    Endpoints that are secured with self-signed certificates aren't supported by Google Cloud. Specifically, the x5c and x5t fields aren't supported and must be removed from the OIDC JWK.

  • An OIDC JWKS file that is uploaded to Google Cloud. By using this method, the endpoint does not need to be public.

SAML

• The IdP supports SAML 2.0.

• The IdP provides a SAML SP metadata document that describes the SAML service provider configuration and contains the IdP's signing certificate.

  Google Cloud uses this certificate to validate SAML assertions and responses.

If your IdP meets these criteria, do the following:

OIDC

Configure your IdP so that your workload can obtain ID tokens that meet the following criteria:

• Tokens are signed using the RS256 or ES256 algorithm.

• Tokens contain an aud claim with the following value:

  https://iam.googleapis.com/projects/PROJECT_NUMBER/locations/global/workloadIdentityPools/POOL_ID/providers/WORKLOAD_PROVIDER_ID
  

  Replace the following:

  • PROJECT_NUMBER: the project number of the Google Cloud project that you use to create workload identity pool.
  • POOL_ID: an ID of your choice that identifies the workload identity pool. You must use the same ID when creating the workload identity pool later.
  • WORKLOAD_PROVIDER_ID: an ID of your choice that identifies the workload identity pool provider. You must use the same ID when creating the workload identity pool provider later.

  Alternatively, you can configure the workload identity pool provider to expect a custom audience.

• Tokens contain an exp claim that is in the future and an iat claim that is in the past.

  The value of exp must be greater than the value of iat by at most 24 hours.

Typically, it's best to use ID tokens when performing a token exchange, because ID tokens reflect the user's identity. If you decide to use access tokens instead, make sure that access tokens meet the following additional requirements:

• Access tokens are JSON Web Token-formatted

• Access tokens contain an ISSUER claim so that the URL ISSUER/.well-known/openid-configuration points to the IdP's OIDC metadata endpoint.

• To upload local JWK keys, see Manage OIDC JWKs.

Note: Workload Identity Federation doesn't support opaque tokens or token introspection.

SAML

Configure your IdP so that SAML assertions contain elements that meet the following criteria:

• an Issuer element that is set to the Entity ID configured in the workload identity pool provider. The issuer format must be omitted or set to urn:oasis:names:tc:SAML:2.0:nameid-format:entity.
• a Subject element with:
  • a NameID element.
  • exactly one SubjectConfirmation element with Method set to urn:oasis:names:tc:SAML:2.0:cm:bearer.
  • a SubjectConfirmationData element with NotOnOrAfter set to a timestamp that occurs in the future and no NotBefore value.

• a Conditions element with:

  • NotBefore omitted or in the past.
  • NotOnOrAfter omitted or in the future.

  • An Audience that is formatted as follows:

    https://iam.googleapis.com/projects/PROJECT_NUMBER/locations/global/workloadIdentityPools/POOL_ID/providers/WORKLOAD_PROVIDER_ID
    

    Replace the following:

    • PROJECT_NUMBER: the project number of the Google Cloud project that you use to create workload identity pool.
    • POOL_ID: an ID of your choice that identifies the workload identity pool. You must use the same ID when creating the workload identity pool later.
    • WORKLOAD_PROVIDER_ID: an ID of your choice that identifies the workload identity pool provider. You must use the same ID when creating the workload identity pool provider later.

• at least one AuthnStatement element.

• a SessionNotOnOrAfter element with a timestamp that occurs in the future. Alternatively, omit the element.

For SAML assertions that are enclosed in a SAML response, the SAML response must contain:

• exactly one assertion that meets the SAML assertion criteria that is described earlier in this section.
• an IssueInstant attribute with a value less than 1 hour in the past.
• the StatusCode urn:oasis:names:tc:SAML:2.0:status:Success.

Either the SAML assertion, the response, or both must be signed.

Configure Workload Identity Federation

You only need to perform these steps once for each IdP. You can then use the same workload identity pool and provider for multiple workloads and across multiple Google Cloud projects.

To start configuring Workload Identity Federation, do the following:

1. In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

   Go to project selector

It's best to use a dedicated project to manage workload identity pools and providers.

2. Make sure that billing is enabled for your Google Cloud project.

Enable the IAM, Resource Manager, Service Account Credentials, and Security Token Service APIs.

Enable the APIs

Manage OIDC JWKs (Optional)

This section shows you how to manage self-uploaded OIDC JWKs in workload identity pool oidc providers.

Create a provider and upload OIDC JWKs

To create OIDC JWKs, see JWT, JWS, JWE, JWK, and JWA Implementations.

To upload an OIDC JWK file when you create a workload identity pool provider, run the gcloud iam workload-identity-pools providers create-oidc command with --jwk-json-path="JWK_JSON_PATH". Replace JWK_JSON_PATH with the path to the JWKs JSON file.

This operation creates uploaded keys with the ones in the file.

Update OIDC JWKs

To update OIDC JWKs, run the gcloud iam workload-identity-pools providers update-oidc command with --jwk-json-path="JWK_JSON_PATH". Replace JWK_JSON_PATH with the path to the JWKs JSON file.

This operation replaces any existing uploaded keys with the ones in the file. You cannot restore the replaced keys.

Delete all uploaded OIDC JWKs

To delete all of the uploaded OIDC JWKs and return to using the issuer URI to fetch the keys, run the gcloud iam workload-identity-pools providers update-oidc command with --jwk-json-path="JWK_JSON_PATH". Replace JWK_JSON_PATH with the path to an empty file. Use the --issuer-uri flag to set the issuer URI.

This operation deletes all of your existing uploaded keys with the ones in the file. You cannot restore the deleted keys.

Define an attribute mapping and condition

The OIDC tokens or SAML assertions issued by your IdP might contain multiple attributes, and you must decide which attribute you want to use as subject identifier (google.subject) in Google Cloud.

Optionally, you can map additional attributes. You can then refer to these attributes when granting access to resources.

OIDC

Your attribute mappings can use the claims embedded in the ID token or access token issued by the external IdP.

You must map one of these claims to google.subject to uniquely identify the user. To protect against spoofing threats, choose a claim with a unique value that can't be changed.

Many IdPs populate the sub claim with a unique and immutable ID. For these IdPs, consider mapping the sub claim to google.subject:

google.subject=assertion.sub

Avoid using a claim like email for this purpose. Email addresses can typically be reassigned or changed, so they don't uniquely and permanently identify a user.

SAML

Your attribute mappings can use the <Subject> and <Attribute> elements embedded in the assertion issued by the external IdP. SAML attributes can be referred to using the following keywords:

• assertion.subject contains the NameID of the authenticated user found in the <Subject> element.
• assertion.attributes['ATTRIBUTE_NAME'] contains a list of values for the like-named <Attribute>.

You must map one of these claims to google.subject to uniquely identify the user. To protect against spoofing threats, choose a claim with a unique value that can't be changed.

Many IdPs populate the NameId with a unique and immutable ID. For these IdPs, consider mapping the NameId attribute to google.subject:

google.subject=assertion.subject

Avoid using an attribute like http://schemas.xmlsoap.org/ws/2005/05/identity/claims/emailaddress for this purpose. Email addresses can typically be reassigned or changed, so they don't uniquely and permanently identify a user.

Optionally, define an attribute condition. Attribute conditions are CEL expressions that can check assertion attributes and target attributes. If the attribute condition evaluates to true for a given credential, the credential is accepted. Otherwise, the credential is rejected.

OIDC

You can use an attribute condition to restrict which users can use Workload Identity Federation to obtain short-lived Google Cloud tokens.

For example, the following condition restricts access to tokens that contain a custom service_account claim with a value true:

assertion.service_account==true

SAML

You can use an attribute condition to restrict which users can use Workload Identity Federation to obtain short-lived Google Cloud tokens.

For example, the following condition restricts access to assertions that contain a custom https://example.com/SAML/Attributes/AllowGcpFederation attribute with a value true:

assertion.attributes['https://example.com/SAML/Attributes/AllowGcpFederation'][0]=='true'

Create the workload identity pool and provider

Required roles

To get the permissions that you need to configure Workload Identity Federation, ask your administrator to grant you the following IAM roles on the project:

• Workload Identity Pool Admin (roles/iam.workloadIdentityPoolAdmin)
• Service Account Admin (roles/iam.serviceAccountAdmin)

For more information about granting roles, see Manage access to projects, folders, and organizations.

You might also be able to get the required permissions through custom roles or other predefined roles.

Alternatively, the IAM Owner (roles/owner) basic role also includes permissions to configure identity federation. You should not grant basic roles in a production environment, but you can grant them in a development or test environment.

You now have collected all the information that you need to create a workload identity pool and provider:

Console

1. In the Google Cloud console, go to the New workload provider and pool page.

   Go to New workload provider and pool

2. Under Create an identity pool, enter the following:

   • Name: Name for the pool. The name is also used as the pool ID. You can't change the pool ID later.
   • Description: Text that describes the purpose of the pool.

3. Click Continue.

4. Configure provider settings as follows:

   OIDC

   • In Select a provider, select OpenID Connect (OIDC).
   • In Provider name, enter a name for the provider. The name is also used as the provider ID. You can't change the provider ID after the provider is created.
   • In Issuer URL, enter the issuer URL of your IdP. The URL must start with https://
   • Optional: In JWK file (JSON), choose a JWK file to upload. If this field is not supplied, Google Cloud attempts to fetch a JWK from the issuer.
   • Allowed audiences: Expected audience of ID tokens.

   SAML

   • In Select a provider, select SAML.
   • In Provider name, enter a name for the provider. The name is also used as the provider ID. You can't change the provider ID after the provider is created.
   • In IDP Metadata file (XML), upload the SAML metadata XML document that is provided by your identity provider.

5. Click Continue.

6. Under Configure provider attributes, add the attribute mappings that you identified earlier in this guide.

7. Under Attribute conditions, enter the attribute condition that you identified earlier in this guide. Leave the field blank if you don't have an attribute condition.

8. To create the workload identity pool and provider, click Save.

gcloud

1. To create a new workload identity pool, execute the following command:

   gcloud iam workload-identity-pools create POOL_ID \
       --location="global" \
       --description="DESCRIPTION" \
       --display-name="DISPLAY_NAME"
   

   Replace the following:

   • POOL_ID: the unique ID for the pool.
   • DISPLAY_NAME: the name of the pool.
   • DESCRIPTION: a description of the pool that you choose. This description appears when you grant access to pool identities.

2. To add a workload identity pool provider, do the following:

   OIDC

   To add an OIDC workload identity pool provider, execute the following command:

   gcloud iam workload-identity-pools providers create-oidc WORKLOAD_PROVIDER_ID \
       --location="global" \
       --workload-identity-pool="POOL_ID" \
       --issuer-uri="ISSUER" \
       --allowed-audiences="AUDIENCE" \
       --attribute-mapping="MAPPINGS" \
       --attribute-condition="CONDITIONS"
       --jwk-json-path="JWK_JSON_PATH"
   

   Replace the following:

   • WORKLOAD_PROVIDER_ID: A unique workload identity pool provider ID of your choice.
   • POOL_ID: The workload identity pool ID that you created earlier.
   • ISSUER: An issuer URI as it is defined in the OIDC metadata.
   • AUDIENCE: The expected audience of ID tokens, which, for many providers, matches the client ID.
   • MAPPINGS: A comma-separated list of attribute mappings that you created earlier in this guide.
   • CONDITIONS: An optional attribute condition that you created earlier in this guide. Remove the parameter if you don't have an attribute condition.
   • JWK_JSON_PATH: An optional path to a locally uploaded OIDC JWKs. If this parameter isn't supplied, Google Cloud instead uses your IdP's /.well-known/openid-configuration path to source the JWKs containing the public keys.

   SAML

   To add a SAML workload identity pool provider, execute the following command:

   gcloud iam workload-identity-pools providers create-saml WORKLOAD_PROVIDER_ID \
       --location="global" \
       --workload-identity-pool="POOL_ID" \
       --idp-metadata-path="IDP_METADATA_PATH" \
       --attribute-mapping="MAPPINGS" \
       --attribute-condition="CONDITIONS"
   

   Replace the following:

   • POOL_ID: the ID of the pool
   • IDP_METADATA_PATH: the local path to the SAML IdP's metadata document
   • MAPPINGS: a comma-separated list of attribute mappings that you created earlier in this guide
   • CONDITIONS: Optional: the attribute condition that you created earlier in this guide

   The prefix gcp- is reserved and can't be used in a workforce identity pool or workforce identity pool provider ID.

   Optional: Accept encrypted SAML assertions from your IdP

   To enable your SAML 2.0 IdP to produce encrypted SAML assertions that can be accepted by workload identity federation, do the following:

   • In workload identity federation, do the following:
   • Create an asymmetric key pair for your workload identity pool provider.
   • Download a certificate file that contains the public key.
   • Configure your SAML IdP to use the public key to encrypt SAML assertions it issues.
   • In your IdP, do the following:
   • Enable assertion encryption, also known as token encryption.
   • Upload the public key that you created in workload identity federation.
   • Confirm that your IdP produces encrypted SAML assertions.

   Note that, even with SAML encryption provider keys configured, workload identity federation can still process a plaintext assertion.

   Create workload identity federation SAML assertion encryption keys

   This section guides you through creating an asymmetric key pair that enables workload identity federation to accept encrypted SAML assertions.

   Google Cloud uses the private key to decrypt the SAML assertions that your IdP issues. To create an asymmetric key pair for use with SAML encryption, run the following command. To learn more, see Supported SAML encryption algorithms.

   gcloud iam workload-identity-pools providers keys create KEY_ID \
       --workload-identity-pool WORKLOAD_POOL_ID \
       --provider WORKLOAD_PROVIDER_ID \
       --location global \
       --use encryption \
       --spec KEY_SPECIFICATION

   Replace the following:

   • KEY_ID: a key name of your choice
   • WORKLOAD_POOL_ID: the pool ID
   • WORKLOAD_PROVIDER_ID: the workforce identity pool provider ID
   • KEY_SPECIFICATION: the key specification, which can be one of rsa-2048, rsa-3072, and rsa-4096.

   After the key pair is created, to download the public key into a certificate file, execute the following command. Only workload identity federation has access to the private key.

   gcloud iam workload-identity-pools providers keys describe KEY_ID \
       --workload-identity-pool WORKLOAD_POOL_ID \
       --provider WORKLOAD_PROVIDER_ID \
       --location global \
       --format "value(keyData.key)" \
       > CERTIFICATE_PATH

   Replace the following:

   • KEY_ID: the key name
   • WORKLOAD_POOL_ID: the pool ID
   • WORKLOAD_PROVIDER_ID: the workforce identity pool provider ID
   • CERTIFICATE_PATH: the path to write the certificate to—for example, saml-certificate.cer or saml-certificate.pem

   Configure your SAML 2.0-compliant IdP to issue encrypted SAML assertions

   Configure your SAML IdP to use the public certificate downloaded from the last step to encrypt the SAML assertions that it issues. Consult your IdP team for specific instructions.

   After you configure your IdP to encrypt SAML assertions, we recommend that you check to make sure that the assertions it generates are actually encrypted. Even with SAML assertion encryption configured, workload identity federation can still process plaintext assertions.

   Delete workload identity federation encryption keys

   To delete SAML encryption keys run the following command:

     gcloud iam workload-identity-pools providers keys delete KEY_ID \
         --workload-identity-pool WORKLOAD_POOL_ID \
         --provider WORKLOAD_PROVIDER_ID \
         --location global

   Replace the following:

   • KEY_ID: the key name
   • WORKLOAD_POOL_ID: the pool ID
   • WORKLOAD_PROVIDER_ID: the workforce identity pool provider ID

   Supported SAML encryption algorithms

   Workload identity federation supports the following key transport algorithms:

   • http://www.w3.org/2001/04/xmlenc#rsa-oaep-mgf1p
   • http://www.w3.org/2009/xmlenc11#rsa-oaep"
   • http://www.w3.org/2001/04/xmlenc#rsa-1_5"

   Workload identity federation supports the following block encryption algorithms:

   • http://www.w3.org/2001/04/xmlenc#aes128-cbc
   • http://www.w3.org/2001/04/xmlenc#aes192-cbc
   • http://www.w3.org/2001/04/xmlenc#aes256-cbc
   • http://www.w3.org/2009/xmlenc11#aes128-gcm
   • http://www.w3.org/2009/xmlenc11#aes256-gcm

Authenticate a workload

You must perform these steps once for each workload.

Allow your external workload to access Google Cloud resources

To provide your workload with access to Google Cloud resources, we recommend that you grant direct resource access to the principal. In this case, the principal is the federated user. Some Google Cloud products have Google Cloud API limitations. If your workload calls an API endpoint that has a limitation, you can instead use service account impersonation. In this case, the principal is the Google Cloud service account, which acts as the identity. You grant access to the service account on the resource.

Direct resource access

You can grant access to a federated identity directly on resources by using the Google Cloud console or the gcloud CLI.

Console

To use the Google Cloud console to grant IAM roles directly on a resource, you must go to the resource's page, and then grant the role. The following example shows you how to go to the Cloud Storage page and grant the role Storage Object Viewer (roles/storage.objectViewer) to a federated identity directly on a Cloud Storage bucket.

1. In the Google Cloud console, go to the Cloud Storage Buckets page.
   

   Go to Buckets

2. In the list of buckets, click the name of the bucket for which you want to grant the role.

3. Select the Permissions tab near the top of the page.

4. Click the Grant access button.

   The Add principals dialog appears.

5. In the New principals field, enter one or more identities that need access to your bucket.

   By subject

   principal://iam.googleapis.com/projects/PROJECT_NUMBER/locations/global/workloadIdentityPools/POOL_ID/subject/SUBJECT
   

   Replace the following:

   • PROJECT_NUMBER: the project number
   • POOL_ID: the workload pool ID
   • SUBJECT: the individual subject mapped from your IdP—for example, [e-mail]

   By group

   principalSet://iam.googleapis.com/projects/PROJECT_NUMBER/locations/global/workloadIdentityPools/POOL_ID/group/GROUP
   

   Replace the following:

   • PROJECT_NUMBER: the project number
   • WORKLOAD_POOL_ID: the workload pool ID
   • GROUP: the group mapped from your IdP—for example: [e-mail]

   By attribute

   principalSet://iam.googleapis.com/projects/PROJECT_NUMBER/locations/global/workloadIdentityPools/POOL_ID/attribute.ATTRIBUTE_NAME/ATTRIBUTE_VALUE
   

   Replace the following:

   • PROJECT_NUMBER: the project number
   • WORKLOAD_POOL_ID: the workload pool ID
   • ATTRIBUTE_NAME: one of the attributes that was mapped from your IdP
   • ATTRIBUTE_VALUE: the value of the attribute

6. Select a role (or roles) from the Select a role drop-down menu. The roles you select appear in the pane with a short description of the permissions they grant.

7. Click Save.

gcloud

To use the gcloud CLI to grant IAM roles on a resource in a project, do the following:

1. Obtain the project number of the project in which the resource is defined.

   gcloud projects describe $(gcloud config get-value core/project) --format=value\(projectNumber\)
   

2. Grant access to the resource.

   To use the gcloud CLI to grant the role Storage Object Viewer (roles/storage.objectViewer) to external identities that meet certain criteria, run the following command.

   By subject

   gcloud storage buckets add-iam-policy-binding BUCKET_ID \
       --role=roles/storage.objectViewer \
       --member="principal://iam.googleapis.com/projects/PROJECT_NUMBER/locations/global/workloadIdentityPools/POOL_ID/subject/SUBJECT"

   By group

   gcloud storage buckets add-iam-policy-binding BUCKET_ID \
       --role=roles/storage.objectViewer \
       --member="principalSet://iam.googleapis.com/projects/PROJECT_NUMBER/locations/global/workloadIdentityPools/POOL_ID/group/GROUP"

   By attribute

   gcloud storage buckets add-iam-policy-binding BUCKET_ID \
       --role=roles/storage.objectViewer \
       --member="principalSet://iam.googleapis.com/projects/PROJECT_NUMBER/locations/global/workloadIdentityPools/POOL_ID/attribute.ATTRIBUTE_NAME/ATTRIBUTE_VALUE"

   Replace the following:

   • BUCKET_ID: the bucket on which to grant access
   • PROJECT_NUMBER: the project number. of the project that contains the workload identity pool
   • POOL_ID: the pool ID of the workload identity pool
   • SUBJECT: the expected value for the attribute that you've mapped to google.subject
   • GROUP: the expected value for the attribute that you've mapped to google.groups
   • ATTRIBUTE_NAME: the name of a custom attribute in your attribute mapping
   • ATTRIBUTE_VALUE: the value of the custom attribute in your attribute mapping

   You can grant roles on any Google Cloud resource that supports IAM allow policies.

   Note: You must use the project number, not the project ID, in the member identifier.

Service account impersonation

1. To create a service account for the external workload, do the following:

   1. Enable the IAM, Security Token Service, and Service Account Credentials APIs.

      Enable the APIs

   2. Create a service account that represents the workload. We recommend that you use a dedicated service account for each workload. The service account doesn't need to be in the same project as the workload identity pool, but you must refer to the project that contains the service account.

   3. Grant the service account access to resources that you want external identities to access.

   4. Grant the Workload Identity User role (roles/iam.workloadIdentityUser) to the service account.

2. To grant access to a federated identity using service account impersonation using the Google Cloud console or the gcloud CLI:

Console

To use the Google Cloud console to grant IAM roles to a federated identity with service account, do the following:

Service Account in the same project

1. To grant access using service account impersonation for a service account in the same project, do the following:

   1. Go to the Workload Identity Pools page.

      Go to Workload Identity Pools

   2. Select Grant access.

   3. In the Grant access to service account dialog, select Grant access using Service Account impersonation.

   4. In the Service accounts list, select the service account for the external identities to impersonate, and do the following:

   5. To choose which identities in the pool can impersonate the service account, perform one of the following actions:

      • To allow only specific identities of the workload identity pool to impersonate the service account, select Only identities matching the filter.

      • In the Attribute name list, select the attribute that you want to filter on.

      • In the Attribute value field, enter the expected value of the attribute; for example, if you use an attribute mapping google.subject=assertion.sub, set Attribute name to subject and Attribute value to the value of the sub claim in tokens that are issued by your external identity provider.

   6. To save the configuration, click Save and then Dismiss.

Service account in a different project

Note: Service accounts from different projects won't appear in the "CONNECTED SERVICE ACCOUNTS" section of your Workload Identity Pool.

1. To grant access using service account impersonation for a service account in a different project, do the following:

   1. Go to the Service Accounts page.

      Go to Service Accounts

   2. Select the service account that you want to impersonate.

   3. Click Manage access.

   4. Click Add principal.

   5. In the New principal field, enter one of the following principal identifiers for the identities in your pool that will impersonate the service account.

      By subject

      principal://iam.googleapis.com/projects/PROJECT_NUMBER/locations/global/workloadIdentityPools/POOL_ID/subject/SUBJECT
      

      Replace the following:

      • PROJECT_NUMBER: the project number
      • POOL_ID: the workload pool ID
      • SUBJECT: the individual subject mapped from your IdP—for example, [e-mail]

      By group

      principalSet://iam.googleapis.com/projects/PROJECT_NUMBER/locations/global/workloadIdentityPools/POOL_ID/group/GROUP
      

      Replace the following:

      • PROJECT_NUMBER: the project number
      • WORKLOAD_POOL_ID: the workload pool ID
      • GROUP: the group mapped from your IdP—for example: [e-mail]

      By attribute

      principalSet://iam.googleapis.com/projects/PROJECT_NUMBER/locations/global/workloadIdentityPools/POOL_ID/attribute.ATTRIBUTE_NAME/ATTRIBUTE_VALUE
      

      Replace the following:

      • PROJECT_NUMBER: the project number
      • WORKLOAD_POOL_ID: the workload pool ID
      • ATTRIBUTE_NAME: one of the attributes that was mapped from your IdP
      • ATTRIBUTE_VALUE: the value of the attribute

      By pool

      principalSet://iam.googleapis.com/projects/PROJECT_NUMBER/locations/global/workloadIdentityPools/POOL_ID/*
      

      Replace the following:

      • PROJECT_NUMBER: the project number
      • WORKLOAD_POOL_ID: the workload pool ID

   6. In Select a role, select the Workload Identity User role (roles/iam.workloadIdentityUser).

   7. To save the configuration, click Save.

gcloud

To use the gcloud CLI to grant the role Workload Identity User (roles/iam.workloadIdentityUser) to external identities that meet certain criteria, run the following command.

By subject

gcloud iam service-accounts add-iam-policy-binding SERVICE_ACCOUNT_EMAIL \
    --role=roles/iam.workloadIdentityUser \
    --member="principal://iam.googleapis.com/projects/PROJECT_NUMBER/locations/global/workloadIdentityPools/POOL_ID/subject/SUBJECT"

By group

gcloud iam service-accounts add-iam-policy-binding SERVICE_ACCOUNT_EMAIL \
    --role=roles/iam.workloadIdentityUser \
    --member="principalSet://iam.googleapis.com/projects/PROJECT_NUMBER/locations/global/workloadIdentityPools/POOL_ID/group/GROUP"

By attribute

gcloud iam service-accounts add-iam-policy-binding SERVICE_ACCOUNT_EMAIL \
    --role=roles/iam.workloadIdentityUser \
    --member="principalSet://iam.googleapis.com/projects/PROJECT_NUMBER/locations/global/workloadIdentityPools/POOL_ID/attribute.ATTRIBUTE_NAME/ATTRIBUTE_VALUE"

Replace the following:

• SERVICE_ACCOUNT_EMAIL: the email address of the service account
• PROJECT_NUMBER: the project number. of the project that contains the workload identity pool
• POOL_ID: the pool ID of the workload identity pool
• SUBJECT: the expected value for the attribute that you've mapped to google.subject
• GROUP: the expected value for the attribute that you've mapped to google.groups
• ATTRIBUTE_NAME: the name of a custom attribute in your attribute mapping
• ATTRIBUTE_VALUE: the value of the custom attribute in your attribute mapping

Note: You must use the project number, not the project ID, in the member identifier.

Download a credential configuration

This section describes how to download the credential configuration using the Google Cloud console.

To let your workload access client libraries, you must first download and configure application default credentials (ADC) by doing the following:

1. In the Google Cloud console, go to the Workload Identity Pools page.

   Go to Workload Identity Pools

2. In the table, select your pool to go the pool's detail page.

3. Click Grant access.

4. Select Grant access using federated identities (Recommended).

5. To download the Application Default Credential (ADC) so that your workload can access client libraries, do the following:

   1. Click Download config.

   2. In the Configure your application dialog, do the following:

      1. In the Provider drop-down list, select your provider.

      2. In OIDC token path or SAML assertion path, enter the path where the token or assertion is located.

      In the Format type drop-down list, select the format.

   3. Click Download configuration, and note the path where you saved the file.

Create a credential configuration

The Cloud Client Libraries, the gcloud CLI, and Terraform, can automatically obtain external credentials, and use these credentials to access Google Cloud. To let libraries and tools complete this process, you have to provide a credential configuration file. This file defines the following:

• Where to obtain external credentials from
• Which workload identity pool and provider to use
• Which service account to impersonate, if you use service account impersonation

The Cloud Client Libraries obtain external credentials from a local file, an HTTP URL, by running a local executable:

• Executable-sourced credentials: The libraries launch an executable whenever they need a new credential. If the executable succeeds in obtaining a new external credential, it must write a JSON document to STDOUT that looks like the following:

  OIDC

  {
    "version": 1,
    "success": true,
    "token_type": "urn:ietf:params:oauth:token-type:id_token",
    "id_token": "HEADER.PAYLOAD.SIGNATURE",
    "expiration_time": 1620499962
  }
  

  If the executable fails to obtain a new credential, it must write a JSON document to STDOUT that looks like the following:

  {
    "version": 1,
    "success": false,
    "code": "401",
    "message": "Caller not authorized."
  }
  

  The JSON documents use the following fields:

  • version: The version of the JSON output. Only version 1 is supported.

  • success: The status of the response.

    When true, the response must contain the fields id_token and token_type. The executable must exit with exit code 0.

    When false, the response must contain the fields code and message and exit with a non-zero value.

  • token_type: The token type of the external credential. Supported values are

    • urn:ietf:params:oauth:token-type:id_token
    • urn:ietf:params:oauth:token-type:jwt

  • id_token: The external credential.

  • expiration_time: The OIDC token expiration time in seconds (unix epoch time). This field is only required when an output file has been specified in the credential configuration.

  • code: The error code string.

  • message: The error message.

  SAML

  {
    "version": 1,
    "success": true,
    "token_type": "urn:ietf:params:oauth:token-type:saml2",
    "saml_response": "...",
    "expiration_time": 1620499962
  }
  

  If the executable fails to obtain a new credential, it must write a JSON document to STDOUT that looks like the following:

  {
    "version": 1,
    "success": false,
    "code": "401",
    "message": "Caller not authorized."
  }
  

  The JSON documents use the following fields:

  • version: The version of the JSON output. Only version 1 is supported.

  • success: The status of the response.

    When true, the response must contain the fields id_token and token_type. The executable must exit with exit code 0.

    When false, the response must contain the fields code and message and exit with a non-zero value.

  • token_type: The token type of the external credential. Must be urn:ietf:params:oauth:token-type:saml2.

  • saml_response: The SAML response or base64-encoded SAML assertion.

  • expiration_time: The assertion expiration time in seconds (unix epoch time). This field is only required when an output file has been specified in the credential configuration.

  • code: The error code string.

  • message: The error message.

  When launching the executable, client libraries set the following environment variables:

  • GOOGLE_EXTERNAL_ACCOUNT_AUDIENCE: Audience from the credential configuration. Always present.
  • GOOGLE_EXTERNAL_ACCOUNT_TOKEN_TYPE: Expected subject token type. Always present.
  • GOOGLE_EXTERNAL_ACCOUNT_IMPERSONATED_EMAIL: Service account email. Only present when service account impersonation is used.
  • GOOGLE_EXTERNAL_ACCOUNT_OUTPUT_FILE: Output file location from the credential configuration. Only present when specified in the credential configuration.

  To use executable-sourced credentials, you must set the environment variable GOOGLE_EXTERNAL_ACCOUNT_ALLOW_EXECUTABLES to 1.

• File-sourced credentials: The libraries read the external credential from a local plain text or JSON file. For example:

  JSON

  {
    "mytoken": "ey...
  }
  

  Text

  ey...
  

  The external credential can be:

  • an OIDC token
  • a SAML response
  • a base64-encoded SAML assertion

  You must periodically update the file so that it always contains a valid credential. For example, if the OIDC token or SAML assertion is valid for one hour, you must refresh the file at least once every hour.

• URL-sourced credentials: The libraries perform a GET request to an HTTP endpoint whenever they need a new credential. The endpoint must return a plain text or JSON response that is equivalent to the format used by file-sourced credentials.

Note: Unlike a service account key, a credential configuration file doesn't contain a private key and doesn't need to be kept confidential. Details about the credential configuration file are available at https://google.aip.dev/auth/4117.

To create a credential configuration file, do the following:

Executable-sourced credentials

gcloud iam workload-identity-pools create-cred-config \
    projects/PROJECT_NUMBER/locations/global/workloadIdentityPools/POOL_ID/providers/WORKLOAD_PROVIDER_ID \
    --service-account=SERVICE_ACCOUNT_EMAIL \
    --service-account-token-lifetime-seconds=SERVICE_ACCOUNT_TOKEN_LIFETIME \
    --output-file=FILEPATH.json \
    --executable-command=EXECUTABLE_COMMAND \
    --executable-timeout-millis=EXECUTABLE_TIMEOUT \
    --executable-output-file=EXECUTABLE_OUTPUT_FILE

Replace the following:

• PROJECT_NUMBER: The project number of the project that contains the workload identity pool.
• POOL_ID: The ID of the workload identity pool.
• WORKLOAD_PROVIDER_ID: The ID of the workload identity pool provider.
• SERVICE_ACCOUNT_EMAIL: If you use service account impersonation, replace with the email address of the service account. Omit this flag if you don't use service account impersonation.
• SERVICE_ACCOUNT_TOKEN_LIFETIME: If you use service account impersonation, replace with the lifetime of the service account access token, in seconds; this defaults to one hour when not provided. Omit this flag if you don't use service account impersonation. To specify a lifetime longer than one hour, you must configure the constraints/iam.allowServiceAccountCredentialLifetimeExtension organizational policy constraint.
• FILEPATH: The file to save the configuration to.
• EXECUTABLE_COMMAND: The full command, including arguments, to run to retrieve the OIDC ID token—for example, --executable-command="/path/to/command --foo=bar".
• EXECUTABLE_TIMEOUT: The optional duration in milliseconds to wait for the executable to run (defaults to 30s).
• EXECUTABLE_OUTPUT_FILE: A path that points to the 3PI credentials generated by the executable. This is useful for caching the credentials. By specifying this path, the Auth libraries will first check for its existence before running the executable.

File-sourced credentials

gcloud iam workload-identity-pools create-cred-config \
    projects/PROJECT_NUMBER/locations/global/workloadIdentityPools/POOL_ID/providers/WORKLOAD_PROVIDER_ID \
    --service-account=SERVICE_ACCOUNT_EMAIL \
    --service-account-token-lifetime-seconds=SERVICE_ACCOUNT_TOKEN_LIFETIME \
    --output-file=FILEPATH.json \
    --credential-source-file=TOKEN_FILEPATH \
    --credential-source-type=SOURCE_TYPE \
    --credential-source-field-name=FIELD_NAME

Replace the following:

• PROJECT_NUMBER: The project number of the project that contains the workload identity pool.
• POOL_ID: The ID of the workload identity pool.
• WORKLOAD_PROVIDER_ID: The ID of the workload identity pool provider.
• SERVICE_ACCOUNT_EMAIL: If you use service account impersonation, replace with the email address of the service account. Omit this flag if you don't use service account impersonation.
• SERVICE_ACCOUNT_TOKEN_LIFETIME: If you use service account impersonation, replace with the lifetime of the service account access token, in seconds; this defaults to one hour when not provided. Omit this flag if you don't use service account impersonation. To specify a lifetime longer than one hour, you must configure the constraints/iam.allowServiceAccountCredentialLifetimeExtension organizational policy constraint.
• FILEPATH: The file to save the configuration to.
• TOKEN_FILEPATH: The path where OIDC ID tokens are stored.
• SOURCE_TYPE: The format of the OIDC ID token file, set to text (default) or json.
• FIELD_NAME: The field in the text file that contains the token (if SOURCE_TYPE is json).

URL-sourced credentials

gcloud iam workload-identity-pools create-cred-config \
    projects/PROJECT_NUMBER/locations/global/workloadIdentityPools/POOL_ID/providers/WORKLOAD_PROVIDER_ID \
    --service-account=SERVICE_ACCOUNT_EMAIL \
    --service-account-token-lifetime-seconds=SERVICE_ACCOUNT_TOKEN_LIFETIME \
    --output-file=FILEPATH.json \
    --credential-source-url="TOKEN_URL" \
    --credential-source-headers="KEY_1=VALUE_1,KEY_2=VALUE_2" \
    --credential-source-type=SOURCE_TYPE \
    --credential-source-field-name=FIELD_NAME

Replace the following:

• PROJECT_NUMBER: Project number of the project that contains the workload identity pool.
• POOL_ID: ID of the workload identity pool.
• WORKLOAD_PROVIDER_ID: ID of the workload identity pool provider
• SERVICE_ACCOUNT_EMAIL: If you use service account impersonation, replace with the mail address of the service account. Omit this flag if you don't use service account impersonation.
• SERVICE_ACCOUNT_TOKEN_LIFETIME: If you use service account impersonation, replace with the lifetime of the service account access token, in seconds; this defaults to one hour when not provided. Omit this flag if you don't use service account impersonation. To specify a lifetime longer than one hour, you must configure the constraints/iam.allowServiceAccountCredentialLifetimeExtension organizational policy constraint.
• FILEPATH: File to save the configuration to.
• TOKEN_URL: URL to retrieve OIDC ID token from
• KEY_n, VALUE_n: Custom headers to include in HTTP request to TOKEN_URL
• SOURCE_TYPE: Format of the OIDC ID token file, set to text (default) or json
• FIELD_NAME: Field in the text file that contains the token (if SOURCE_TYPE is json)

Use the credential configuration to access Google Cloud

To let tools and client libraries use your credential configuration, do the following:

1. Initialize an environment variable GOOGLE_APPLICATION_CREDENTIALS and point it to the credential configuration file:

   Bash

     export GOOGLE_APPLICATION_CREDENTIALS=`pwd`/FILEPATH.json
     

   where FILEPATH is the relative path to the credential configuration file.

   PowerShell

     $env:GOOGLE_APPLICATION_CREDENTIALS = Resolve-Path 'FILEPATH.json'
     

   where FILEPATH is the relative path to the credential configuration file.

2. Use a client library or tool that supports Workload Identity Federation and can find credentials automatically:

   C++

   The Google Cloud Client Libraries for C++ support Workload Identity Federation since version v2.6.0. To use Workload Identity Federation, you must build the client libraries with version 1.36.0 or later of gRPC.

   Go

   Client libraries for Go support Workload Identity Federation if they use version v0.0.0-20210218202405-ba52d332ba99 or later of the golang.org/x/oauth2 module.

   To check which version of this module your client library uses, run the following commands:

   cd $GOPATH/src/cloud.google.com/go
   go list -m golang.org/x/oauth2
   

   Java

   Client libraries for Java support Workload Identity Federation if they use version 0.24.0 or later of the com.google.auth:google-auth-library-oauth2-http artifact.

   To check which version of this artifact your client library uses, run the following Maven command in your application directory:

   mvn dependency:list -DincludeArtifactIds=google-auth-library-oauth2-http
   

   Node.js

   Client libraries for Node.js support Workload Identity Federation if they use version 7.0.2 or later of the google-auth-library package.

   To check which version of this package your client library uses, run the following command in your application directory:

   npm list google-auth-library
   

   When you create a GoogleAuth object, you can specify a project ID, or you can allow GoogleAuth to find the project ID automatically. To find the project ID automatically, the service account in the configuration file must have the Browser role (roles/browser), or a role with equivalent permissions, on your project. For details, see the README for the google-auth-library package.

   Python

   Client libraries for Python support Workload Identity Federation if they use version 1.27.0 or later of the google-auth package.

   To check which version of this package your client library uses, run the following command in the environment where the package is installed:

   pip show google-auth
   

   To specify a project ID for the authentication client, you can set the GOOGLE_CLOUD_PROJECT environment variable, or you can allow the client to find the project ID automatically. To find the project ID automatically, the service account in the configuration file must have the Browser role (roles/browser), or a role with equivalent permissions, on your project. For details, see the user guide for the google-auth package.

   gcloud

   To authenticate using Workload Identity Federation, use the gcloud auth login command:

   gcloud auth login --cred-file=FILEPATH.json
   

   Replace FILEPATH with the path to the credential configuration file.

   Support for Workload Identity Federation in gcloud CLI is available in version 363.0.0 and later versions of the gcloud CLI.

   Terraform

   The Google Cloud provider supports Workload Identity Federation if you use version 3.61.0 or later:

   terraform {
     required_providers {
       google = {
         source  = "hashicorp/google"
         version = "~> 3.61.0"
       }
     }
   }
   

   bq

   To authenticate using Workload Identity Federation, use the gcloud auth login command, as follows:

   gcloud auth login --cred-file=FILEPATH.json
   

   Replace FILEPATH with the path to the credential configuration file.

   Support for Workload Identity Federation in bq is available in version 390.0.0 and later versions of the gcloud CLI.

What's next

• Read more about Workload Identity Federation.
• Learn about best practices for using Workload Identity Federation.
• See how you can manage workload identity pools and providers.