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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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\u003eThis page outlines how to override the default authentication credentials used by client libraries when interacting with Google Cloud Services.\u003c/p\u003e\n"],["\u003cp\u003eBy default, client libraries utilize Application Default Credentials, but you can specify alternative credentials using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe provided example demonstrates loading authentication credentials from a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eThe documentation includes links to specific examples for various \u003ccode\u003e*Client\u003c/code\u003e classes such as \u003ccode\u003eDatasetServiceClient\u003c/code\u003e, \u003ccode\u003eJobServiceClient\u003c/code\u003e, \u003ccode\u003eModelServiceClient\u003c/code\u003e, and others, all within the \u003ccode\u003ebigquerycontrol_v2\u003c/code\u003e namespace.\u003c/p\u003e\n"],["\u003cp\u003eFor comprehensive details on managing service account keys, refer to the "Best practices for managing service account keys" guide.\u003c/p\u003e\n"]]],[],null,[]]
