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 details how to override the default Application Default Credentials (ADC) for authenticating with Google Cloud Services.\u003c/p\u003e\n"],["\u003cp\u003eThe latest version is 2.37.0-rc, and the content lists available versions down to 2.11.0, covering a range of documentation for overriding authentication.\u003c/p\u003e\n"],["\u003cp\u003eYou can override the default credentials by using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, such as by loading a service account key file as shown in the provided example code.\u003c/p\u003e\n"],["\u003cp\u003eExamples for overriding authentication are available for various client 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 document also recommends checking the Best practices for managing service account keys and to consult the Authentication Components section for more information on the \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects.\u003c/p\u003e\n"]]],[],null,["Version 2.21.0keyboard_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/2.21.0/run_v2_1_1ExecutionsClient-service-account-snippet)\n- [`run_v2::JobsClient`](/cpp/docs/reference/run/2.21.0/run_v2_1_1JobsClient-service-account-snippet)\n- [`run_v2::RevisionsClient`](/cpp/docs/reference/run/2.21.0/run_v2_1_1RevisionsClient-service-account-snippet)\n- [`run_v2::ServicesClient`](/cpp/docs/reference/run/2.21.0/run_v2_1_1ServicesClient-service-account-snippet)\n- [`run_v2::TasksClient`](/cpp/docs/reference/run/2.21.0/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."]]