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\u003eThis page documents how to override the default authentication credentials for Google Cloud services, which normally use Application Default Credentials (ADC).\u003c/p\u003e\n"],["\u003cp\u003eOverriding the default authentication can be accomplished by providing a \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, such as by loading a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eThe provided example demonstrates how to load a service account key file to override authentication credentials, which is a simple use case for overriding the default credentials.\u003c/p\u003e\n"],["\u003cp\u003eLinks to examples for various \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 are readily available to see how to accomplish this override in those specific clients.\u003c/p\u003e\n"],["\u003cp\u003eA list of historical versions of the documentation is available on this page, starting with the latest release candidate \u003ccode\u003e2.37.0-rc\u003c/code\u003e and going back to version \u003ccode\u003e2.11.0\u003c/code\u003e.\u003c/p\u003e\n"]]],[],null,["Version 2.23.0keyboard_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/2.23.0/run_v2_1_1ExecutionsClient-service-account-snippet)\n- [`run_v2::JobsClient`](/cpp/docs/reference/run/2.23.0/run_v2_1_1JobsClient-service-account-snippet)\n- [`run_v2::RevisionsClient`](/cpp/docs/reference/run/2.23.0/run_v2_1_1RevisionsClient-service-account-snippet)\n- [`run_v2::ServicesClient`](/cpp/docs/reference/run/2.23.0/run_v2_1_1ServicesClient-service-account-snippet)\n- [`run_v2::TasksClient`](/cpp/docs/reference/run/2.23.0/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."]]