def METHOD_NAME(api_portal_name: Optional[pulumi.Input[str]] = None,
                                        domain_name: Optional[pulumi.Input[str]] = None,
                                        resource_group_name: Optional[pulumi.Input[str]] = None,
                                        service_name: Optional[pulumi.Input[str]] = None,
                                        opts: Optional[pulumi.InvokeOptions] = None) -> pulumi.Output[GetApiPortalCustomDomainResult]:
    """
    Get the API portal custom domain.
    :param str api_portal_name: The name of API portal.
    :param str domain_name: The name of the API portal custom domain.
    :param str resource_group_name: The name of the resource group that contains the resource. You can obtain this value from the Azure Resource Manager API or the portal.
    :param str service_name: The name of the Service resource.
    """
    ...