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::servicecontrol_v1::QuotaControllerClient(
google::cloud::servicecontrol_v1::MakeQuotaControllerConnection(
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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 provides documentation for overriding default authentication credentials when using Google Cloud client libraries, specifically for the Service Control API.\u003c/p\u003e\n"],["\u003cp\u003eThe client libraries typically use Application Default Credentials (ADC), but users can override this by using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe latest release candidate is version 2.37.0-rc and the current version is 2.34.0.\u003c/p\u003e\n"],["\u003cp\u003eExamples are provided for \u003ccode\u003eQuotaControllerClient\u003c/code\u003e and \u003ccode\u003eServiceControllerClient\u003c/code\u003e classes to demonstrate how to load a service account key file for authentication.\u003c/p\u003e\n"],["\u003cp\u003eThe documentation also directs users to the "Best practices for managing service account keys" guide and the "Authentication Components" page for further details.\u003c/p\u003e\n"]]],[],null,[]]
