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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 multiple older versions available dating back to 2.11.0.\u003c/p\u003e\n"],["\u003cp\u003eClient libraries typically use Application Default Credentials for authentication, but these can be overridden when necessary.\u003c/p\u003e\n"],["\u003cp\u003eAuthentication can be overridden by providing the UnifiedCredentialsOption, demonstrated through an example of loading a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eExamples for overriding authentication 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\u003eRefer to the "Best practices for managing service account keys" guide and the "Authentication Components" section for further information.\u003c/p\u003e\n"]]],[],null,[]]
