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::run_v2::ExecutionsClient(
google::cloud::run_v2::MakeExecutionsConnection(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 webpage details how to override default authentication credentials, which typically use Application Default Credentials, for Google Cloud Services.\u003c/p\u003e\n"],["\u003cp\u003eYou can override the default credentials by using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e and providing a service account key file, as demonstrated in the provided code example.\u003c/p\u003e\n"],["\u003cp\u003eThe documentation provides versioned links for various versions of \u003ccode\u003erun-override-authentication\u003c/code\u003e, ranging from version 2.11.0 up to the latest release candidate 2.37.0-rc.\u003c/p\u003e\n"],["\u003cp\u003eExamples for overriding credentials are also provided for several \u003ccode\u003e*Client\u003c/code\u003e classes including \u003ccode\u003erun_v2::ExecutionsClient\u003c/code\u003e, \u003ccode\u003erun_v2::JobsClient\u003c/code\u003e, \u003ccode\u003erun_v2::RevisionsClient\u003c/code\u003e, \u003ccode\u003erun_v2::ServicesClient\u003c/code\u003e, and \u003ccode\u003erun_v2::TasksClient\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe page also links to best practices for managing service account keys and to more information on creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects.\u003c/p\u003e\n"]]],[],null,["Version 2.29.0keyboard_arrow_down\n\n- [2.42.0-rc (latest)](/cpp/docs/reference/run/latest/run-override-authentication)\n- [2.41.0](/cpp/docs/reference/run/2.41.0/run-override-authentication)\n- [2.40.0](/cpp/docs/reference/run/2.40.0/run-override-authentication)\n- [2.39.0](/cpp/docs/reference/run/2.39.0/run-override-authentication)\n- [2.38.0](/cpp/docs/reference/run/2.38.0/run-override-authentication)\n- [2.37.0](/cpp/docs/reference/run/2.37.0/run-override-authentication)\n- [2.36.0](/cpp/docs/reference/run/2.36.0/run-override-authentication)\n- [2.35.0](/cpp/docs/reference/run/2.35.0/run-override-authentication)\n- [2.34.0](/cpp/docs/reference/run/2.34.0/run-override-authentication)\n- [2.33.0](/cpp/docs/reference/run/2.33.0/run-override-authentication)\n- [2.32.0](/cpp/docs/reference/run/2.32.0/run-override-authentication)\n- [2.31.0](/cpp/docs/reference/run/2.31.0/run-override-authentication)\n- [2.30.0](/cpp/docs/reference/run/2.30.0/run-override-authentication)\n- [2.29.0](/cpp/docs/reference/run/2.29.0/run-override-authentication)\n- [2.28.0](/cpp/docs/reference/run/2.28.0/run-override-authentication)\n- [2.27.0](/cpp/docs/reference/run/2.27.0/run-override-authentication)\n- [2.26.0](/cpp/docs/reference/run/2.26.0/run-override-authentication)\n- [2.25.1](/cpp/docs/reference/run/2.25.1/run-override-authentication)\n- [2.24.0](/cpp/docs/reference/run/2.24.0/run-override-authentication)\n- [2.23.0](/cpp/docs/reference/run/2.23.0/run-override-authentication)\n- [2.22.1](/cpp/docs/reference/run/2.22.1/run-override-authentication)\n- [2.21.0](/cpp/docs/reference/run/2.21.0/run-override-authentication)\n- [2.20.0](/cpp/docs/reference/run/2.20.0/run-override-authentication)\n- [2.19.0](/cpp/docs/reference/run/2.19.0/run-override-authentication)\n- [2.18.0](/cpp/docs/reference/run/2.18.0/run-override-authentication)\n- [2.17.0](/cpp/docs/reference/run/2.17.0/run-override-authentication)\n- [2.16.0](/cpp/docs/reference/run/2.16.0/run-override-authentication)\n- [2.15.1](/cpp/docs/reference/run/2.15.1/run-override-authentication)\n- [2.14.0](/cpp/docs/reference/run/2.14.0/run-override-authentication)\n- [2.13.0](/cpp/docs/reference/run/2.13.0/run-override-authentication)\n- [2.12.0](/cpp/docs/reference/run/2.12.0/run-override-authentication)\n- [2.11.0](/cpp/docs/reference/run/2.11.0/run-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::run_v2::ExecutionsClient(\n google::cloud::run_v2::MakeExecutionsConnection(options));\n }\n\nFollow these links to find examples for other `*Client` classes:\n\n- [`run_v2::ExecutionsClient`](/cpp/docs/reference/run/2.29.0/run_v2_1_1ExecutionsClient-service-account-snippet)\n- [`run_v2::JobsClient`](/cpp/docs/reference/run/2.29.0/run_v2_1_1JobsClient-service-account-snippet)\n- [`run_v2::RevisionsClient`](/cpp/docs/reference/run/2.29.0/run_v2_1_1RevisionsClient-service-account-snippet)\n- [`run_v2::ServicesClient`](/cpp/docs/reference/run/2.29.0/run_v2_1_1ServicesClient-service-account-snippet)\n- [`run_v2::TasksClient`](/cpp/docs/reference/run/2.29.0/run_v2_1_1TasksClient-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."]]