gcloud iam workload-identity-pools providers create-saml

Each key must be a string specifying the Google Cloud IAM attribute to map to.

The following keys are supported:

• google.subject: The principal IAM is authenticating. You can reference this value in IAM bindings. This is also the subject that appears in Cloud Logging logs. Cannot exceed 127 bytes.

• google.groups: Groups the external identity belongs to. You can grant groups access to resources using an IAM principalSet binding; access applies to all members of the group.

You can also provide custom attributes by specifying attribute.{custom_attribute}, where {custom_attribute} is the name of the custom attribute to be mapped. You can define a maximum of 50 custom attributes. The maximum length of a mapped attribute key is 100 characters, and the key can only contain the characters [a-z0-9_].

You can reference these attributes in IAM policies to define fine-grained access for a workload to Google Cloud resources. For example:

• google.subject: principal://iam.googleapis.com/projects/{project}/locations/{location}/workloadIdentityPools/{pool}/subject/{value}

• google.groups: principalSet://iam.googleapis.com/projects/{project}/locations/{location}/workloadIdentityPools/{pool}/group/{value}

• attribute.{custom_attribute}: principalSet://iam.googleapis.com/projects/{project}/locations/{location}/workloadIdentityPools/{pool}/attribute.{custom_attribute}/{value}

Each value must be a Common Expression Language function that maps an identity provider credential to the normalized attribute specified by the corresponding map key.

You can use the assertion keyword in the expression to access a JSON representation of the authentication credential issued by the provider.

The maximum length of an attribute mapping expression is 2048 characters. When evaluated, the total size of all mapped attributes must not exceed 8KB.

For AWS providers, the following rules apply:

• If no attribute mapping is defined, the following default mapping applies:

{
  "google.subject":"assertion.arn",
  "attribute.aws_role":
      "assertion.arn.contains('assumed-role')"
      " ? assertion.arn.extract('{account_arn}assumed-role/')"
      "   + 'assumed-role/'"
      "   + assertion.arn.extract('assumed-role/{role_name}/')"
      " : assertion.arn",
}

• If any custom attribute mappings are defined, they must include a mapping to the google.subject attribute.

• Custom attribute mappings must be defined, and must include a mapping to the google.subject attribute. For example, the following maps the sub claim of the incoming credential to the subject attribute on a Google token.

{"google.subject": "assertion.sub"}

The expression must output a boolean representing whether to allow the federation.

The following keywords may be referenced in the expressions:

• assertion: JSON representing the authentication credential issued by the provider.
• google: The Google attributes mapped from the assertion in the attribute_mappings.
• attribute: The custom attributes mapped from the assertion in the attribute_mappings.

The maximum length of the attribute condition expression is 4096 characters. If unspecified, all valid authentication credential are accepted.

The following example shows how to only allow credentials with a mapped google.groups value of admins:

"'admins' in google.groups"