Unless otherwise configured, the client libraries useApplication Default Credentialsto authenticate with Google Cloud Services. While this works for most applications, in some cases you may need to override this default. You can do so by providing theUnifiedCredentialsOptionThe following example shows how to explicitly load a service account key file:
[](std::string const& keyfile) {
auto is = std::ifstream(keyfile);
is.exceptions(std::ios::badbit); // Minimal error handling in examples
auto contents = std::string(std::istreambuf_iterator<char>(is.rdbuf()), {});
auto options =
google::cloud::Options{}.set<google::cloud::UnifiedCredentialsOption>(
google::cloud::MakeServiceAccountCredentials(contents));
return google::cloud::bigquery_analyticshub_v1::AnalyticsHubServiceClient(
google::cloud::bigquery_analyticshub_v1::
MakeAnalyticsHubServiceConnection(options));
}
Follow these links to find examples for other*Clientclasses:
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-09-04 UTC."],[[["\u003cp\u003eThe latest release candidate version is 2.37.0-rc, and multiple previous versions of the BigQuery C++ client libraries are available, starting from version 2.11.0 up to the most recently released version, 2.36.0.\u003c/p\u003e\n"],["\u003cp\u003eBy default, the client libraries authenticate with Google Cloud Services using Application Default Credentials, which can be overridden in certain cases.\u003c/p\u003e\n"],["\u003cp\u003eOverriding default authentication can be achieved by using \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, as demonstrated by explicitly loading a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eThe documentation provides links to examples for overriding authentication with various \u003ccode\u003e*Client\u003c/code\u003e classes, including \u003ccode\u003eAnalyticsHubServiceClient\u003c/code\u003e, \u003ccode\u003eMetastoreServiceClient\u003c/code\u003e, and others.\u003c/p\u003e\n"],["\u003cp\u003eRefer to the "Best practices for managing service account keys" guide for detailed information on service account key management and the "Authentication Components" for additional information on the creation of \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects.\u003c/p\u003e\n"]]],[],null,["Version 2.24.0keyboard_arrow_down\n\n- [2.42.0-rc (latest)](/cpp/docs/reference/bigquery/latest/bigquery-override-authentication)\n- [2.41.0](/cpp/docs/reference/bigquery/2.41.0/bigquery-override-authentication)\n- [2.40.0](/cpp/docs/reference/bigquery/2.40.0/bigquery-override-authentication)\n- [2.39.0](/cpp/docs/reference/bigquery/2.39.0/bigquery-override-authentication)\n- [2.38.0](/cpp/docs/reference/bigquery/2.38.0/bigquery-override-authentication)\n- [2.37.0](/cpp/docs/reference/bigquery/2.37.0/bigquery-override-authentication)\n- [2.36.0](/cpp/docs/reference/bigquery/2.36.0/bigquery-override-authentication)\n- [2.35.0](/cpp/docs/reference/bigquery/2.35.0/bigquery-override-authentication)\n- [2.34.0](/cpp/docs/reference/bigquery/2.34.0/bigquery-override-authentication)\n- [2.33.0](/cpp/docs/reference/bigquery/2.33.0/bigquery-override-authentication)\n- [2.32.0](/cpp/docs/reference/bigquery/2.32.0/bigquery-override-authentication)\n- [2.31.0](/cpp/docs/reference/bigquery/2.31.0/bigquery-override-authentication)\n- [2.30.0](/cpp/docs/reference/bigquery/2.30.0/bigquery-override-authentication)\n- [2.29.0](/cpp/docs/reference/bigquery/2.29.0/bigquery-override-authentication)\n- [2.28.0](/cpp/docs/reference/bigquery/2.28.0/bigquery-override-authentication)\n- [2.27.0](/cpp/docs/reference/bigquery/2.27.0/bigquery-override-authentication)\n- [2.26.0](/cpp/docs/reference/bigquery/2.26.0/bigquery-override-authentication)\n- [2.25.1](/cpp/docs/reference/bigquery/2.25.1/bigquery-override-authentication)\n- [2.24.0](/cpp/docs/reference/bigquery/2.24.0/bigquery-override-authentication)\n- [2.23.0](/cpp/docs/reference/bigquery/2.23.0/bigquery-override-authentication)\n- [2.22.1](/cpp/docs/reference/bigquery/2.22.1/bigquery-override-authentication)\n- [2.21.0](/cpp/docs/reference/bigquery/2.21.0/bigquery-override-authentication)\n- [2.20.0](/cpp/docs/reference/bigquery/2.20.0/bigquery-override-authentication)\n- [2.19.0](/cpp/docs/reference/bigquery/2.19.0/bigquery-override-authentication)\n- [2.18.0](/cpp/docs/reference/bigquery/2.18.0/bigquery-override-authentication)\n- [2.17.0](/cpp/docs/reference/bigquery/2.17.0/bigquery-override-authentication)\n- [2.16.0](/cpp/docs/reference/bigquery/2.16.0/bigquery-override-authentication)\n- [2.15.1](/cpp/docs/reference/bigquery/2.15.1/bigquery-override-authentication)\n- [2.14.0](/cpp/docs/reference/bigquery/2.14.0/bigquery-override-authentication)\n- [2.13.0](/cpp/docs/reference/bigquery/2.13.0/bigquery-override-authentication)\n- [2.12.0](/cpp/docs/reference/bigquery/2.12.0/bigquery-override-authentication)\n- [2.11.0](/cpp/docs/reference/bigquery/2.11.0/bigquery-override-authentication) \n\nHow to Override the Authentication Credentials\n==============================================\n\nUnless otherwise configured, the client libraries use [Application Default Credentials](https://cloud.google.com/docs/authentication#adc) to authenticate with Google Cloud Services. While this works for most applications, in some cases you may need to override this default. You can do so by providing the [UnifiedCredentialsOption](https://cloud.google.com/cpp/docs/reference/common/latest/structgoogle_1_1cloud_1_1UnifiedCredentialsOption.html) The following example shows how to explicitly load a service account key file: \n\n [](std::string const& keyfile) {\n auto is = std::ifstream(keyfile);\n is.exceptions(std::ios::badbit); // Minimal error handling in examples\n auto contents = std::string(std::istreambuf_iterator\u003cchar\u003e(is.rdbuf()), {});\n auto options =\n google::cloud::Options{}.set\u003cgoogle::cloud::UnifiedCredentialsOption\u003e(\n google::cloud::MakeServiceAccountCredentials(contents));\n return google::cloud::bigquery_analyticshub_v1::AnalyticsHubServiceClient(\n google::cloud::bigquery_analyticshub_v1::\n MakeAnalyticsHubServiceConnection(options));\n }\n\nFollow these links to find examples for other `*Client` classes:\n\n- [`bigquery_analyticshub_v1::AnalyticsHubServiceClient`](/cpp/docs/reference/bigquery/2.24.0/bigquery_analyticshub_v1_1_1AnalyticsHubServiceClient-service-account-snippet)\n- [`bigquery_biglake_v1::MetastoreServiceClient`](/cpp/docs/reference/bigquery/2.24.0/bigquery_biglake_v1_1_1MetastoreServiceClient-service-account-snippet)\n- [`bigquery_connection_v1::ConnectionServiceClient`](/cpp/docs/reference/bigquery/2.24.0/bigquery_connection_v1_1_1ConnectionServiceClient-service-account-snippet)\n- [`bigquery_datapolicies_v1::DataPolicyServiceClient`](/cpp/docs/reference/bigquery/2.24.0/bigquery_datapolicies_v1_1_1DataPolicyServiceClient-service-account-snippet)\n- [`bigquery_datatransfer_v1::DataTransferServiceClient`](/cpp/docs/reference/bigquery/2.24.0/bigquery_datatransfer_v1_1_1DataTransferServiceClient-service-account-snippet)\n- [`bigquery_migration_v2::MigrationServiceClient`](/cpp/docs/reference/bigquery/2.24.0/bigquery_migration_v2_1_1MigrationServiceClient-service-account-snippet)\n- [`bigquery_reservation_v1::ReservationServiceClient`](/cpp/docs/reference/bigquery/2.24.0/bigquery_reservation_v1_1_1ReservationServiceClient-service-account-snippet)\n- [`bigquery_storage_v1::BigQueryReadClient`](/cpp/docs/reference/bigquery/2.24.0/bigquery_storage_v1_1_1BigQueryReadClient-service-account-snippet)\n- [`bigquery_storage_v1::BigQueryWriteClient`](/cpp/docs/reference/bigquery/2.24.0/bigquery_storage_v1_1_1BigQueryWriteClient-service-account-snippet)\n\nKeep in mind that we chose this as an example because it is relatively easy to understand. Consult the [Best practices for managing service account keys](https://cloud.google.com/iam/docs/best-practices-for-managing-service-account-keys) guide for more details.\n\n###### See Also\n\n[Authentication Components](https://cloud.google.com/cpp/docs/reference/common/latest/group__guac.html) - for more information on the factory functions to create [`google::cloud::Credentials`](https://cloud.google.com/cpp/docs/reference/common/latest/classgoogle_1_1cloud_1_1Credentials.html) objects."]]