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::bigquerycontrol_v2::DatasetServiceClient(
google::cloud::bigquerycontrol_v2::MakeDatasetServiceConnectionRest(
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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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\u003eThe latest version of the documentation is 2.37.0-rc, with multiple previous versions available, including 2.36.0, 2.35.0, 2.34.0, 2.33.0, 2.32.0, 2.31.0, 2.30.0, 2.29.0, 2.28.0 and 2.27.0.\u003c/p\u003e\n"],["\u003cp\u003eClient libraries default to using Application Default Credentials for Google Cloud Service authentication, but this can be overridden.\u003c/p\u003e\n"],["\u003cp\u003eYou can override the default authentication by using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e and providing the credentials, such as explicitly loading a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eThe documentation includes examples for how to override credentials for various \u003ccode\u003e*Client\u003c/code\u003e classes in version 2.32.0, such as \u003ccode\u003eDatasetServiceClient\u003c/code\u003e, \u003ccode\u003eJobServiceClient\u003c/code\u003e, \u003ccode\u003eModelServiceClient\u003c/code\u003e, and others.\u003c/p\u003e\n"],["\u003cp\u003eRefer to the "Best practices for managing service account keys" guide and the "Authentication Components" documentation for further details on managing authentication.\u003c/p\u003e\n"]]],[],null,[]]
