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::kms_inventory_v1::KeyDashboardServiceClient(
google::cloud::kms_inventory_v1::MakeKeyDashboardServiceConnection(
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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 document provides version-specific documentation for overriding authentication credentials in Google Cloud C++ client libraries, focusing on the Key Management Service (KMS).\u003c/p\u003e\n"],["\u003cp\u003eThe latest release candidate version available is 2.37.0-rc, and the document lists versions from 2.37.0-rc down to version 2.10.1.\u003c/p\u003e\n"],["\u003cp\u003eThe document details how to override the default Application Default Credentials by utilizing the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, specifically demonstrating how to load a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eExamples for overriding service accounts are provided for various client classes, including \u003ccode\u003eKeyDashboardServiceClient\u003c/code\u003e, \u003ccode\u003eKeyTrackingServiceClient\u003c/code\u003e, \u003ccode\u003eAutokeyAdminClient\u003c/code\u003e, \u003ccode\u003eAutokeyClient\u003c/code\u003e, \u003ccode\u003eEkmServiceClient\u003c/code\u003e, and \u003ccode\u003eKeyManagementServiceClient\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eUsers are directed to the "Best practices for managing service account keys" guide for advanced details and to the Authentication Components section for more on \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e.\u003c/p\u003e\n"]]],[],null,[]]
