Unless otherwise configured, the client libraries use Application Default Credentials 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 The 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 *Client classes:
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14 UTC."],[[["\u003cp\u003eThis page details how to override the default Application Default Credentials (ADC) for authenticating with Google Cloud Services using the C++ client libraries.\u003c/p\u003e\n"],["\u003cp\u003eYou can override the default credentials by providing the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, demonstrated with an example of loading a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eThe latest release candidate is version \u003ccode\u003e2.37.0-rc\u003c/code\u003e, while the latest fully released version is \u003ccode\u003e2.36.0\u003c/code\u003e for the service override.\u003c/p\u003e\n"],["\u003cp\u003eExamples are 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\u003eRefer to the "Best practices for managing service account keys" guide and the "Authentication Components" for further information on managing service account keys and creating credentials objects, respectively.\u003c/p\u003e\n"]]],[],null,[]]
