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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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\u003eThe latest version available is 2.37.0-rc, with numerous other versions from 2.36.0 down to 2.11.0 also being accessible.\u003c/p\u003e\n"],["\u003cp\u003eThe client libraries typically use Application Default Credentials for authentication, but you can override this behavior.\u003c/p\u003e\n"],["\u003cp\u003eYou can override default authentication by using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, demonstrated through the loading of a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eExamples for overriding authentication with a service account are available for \u003ccode\u003ebilling_budgets_v1::BudgetServiceClient\u003c/code\u003e, \u003ccode\u003ebilling_v1::CloudBillingClient\u003c/code\u003e, and \u003ccode\u003ebilling_v1::CloudCatalogClient\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eFor managing service account keys, refer to the provided "Best practices for managing service account keys" guide, and for additional information about creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects, see the Authentication Components documentation.\u003c/p\u003e\n"]]],[],null,[]]
