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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 details how to override the default authentication credentials used by client libraries when interacting with Google Cloud Services, using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe latest release candidate version is \u003ccode\u003e2.37.0-rc\u003c/code\u003e, and the page also lists previous versions back to \u003ccode\u003e2.11.0\u003c/code\u003e, with links to each versions documentation.\u003c/p\u003e\n"],["\u003cp\u003eThe provided code example demonstrates explicitly loading a service account key file to override the default Application Default Credentials (ADC) using \u003ccode\u003eMakeServiceAccountCredentials\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eSpecific examples for \u003ccode\u003eBudgetServiceClient\u003c/code\u003e, \u003ccode\u003eCloudBillingClient\u003c/code\u003e, and \u003ccode\u003eCloudCatalogClient\u003c/code\u003e classes are linked, showcasing how to apply the credential override in different client contexts.\u003c/p\u003e\n"],["\u003cp\u003eThe page also links to best practices for managing service account keys and other authentication components for more information.\u003c/p\u003e\n"]]],[],null,[]]
