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::billing_budgets_v1::BudgetServiceClient(
google::cloud::billing_budgets_v1::MakeBudgetServiceConnection(
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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 various versions of the Google Cloud C++ client library, ranging from version 2.11.0 up to the latest release candidate 2.37.0-rc.\u003c/p\u003e\n"],["\u003cp\u003eThe client libraries default to using Application Default Credentials for authentication with Google Cloud services, but this can be overridden if necessary.\u003c/p\u003e\n"],["\u003cp\u003eYou can override the default authentication by utilizing \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e and explicitly loading a service account key file, as shown in the provided code example.\u003c/p\u003e\n"],["\u003cp\u003eExamples of overriding authentication credentials for \u003ccode\u003eBudgetServiceClient\u003c/code\u003e, \u003ccode\u003eCloudBillingClient\u003c/code\u003e, and \u003ccode\u003eCloudCatalogClient\u003c/code\u003e are available through provided links.\u003c/p\u003e\n"],["\u003cp\u003eFor more details on best practices for service account key management, consult the referenced guide, and for more information on credential object creation, consult the "Authentication Components" link.\u003c/p\u003e\n"]]],[],null,[]]
