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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 client libraries default to using Application Default Credentials for authentication with Google Cloud Services, but this can be overridden.\u003c/p\u003e\n"],["\u003cp\u003eYou can override the default authentication by providing the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, such as 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, using the \u003ccode\u003eMakeServiceAccountCredentials\u003c/code\u003e function.\u003c/p\u003e\n"],["\u003cp\u003eLinks to examples for different \u003ccode\u003e*Client\u003c/code\u003e classes like \u003ccode\u003eDatasetServiceClient\u003c/code\u003e, \u003ccode\u003eJobServiceClient\u003c/code\u003e, and \u003ccode\u003eModelServiceClient\u003c/code\u003e are available.\u003c/p\u003e\n"],["\u003cp\u003eRefer to the "Best practices for managing service account keys" guide for further details on managing service account credentials.\u003c/p\u003e\n"]]],[],null,[]]
