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::monitoring_dashboard_v1::DashboardsServiceClient(
google::cloud::monitoring_dashboard_v1::MakeDashboardsServiceConnection(
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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 Application Default Credentials (ADC) for authenticating with Google Cloud Services using C++ client libraries.\u003c/p\u003e\n"],["\u003cp\u003eYou can override the default credentials by using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, and this page provides an example of loading a service account key file to authenticate.\u003c/p\u003e\n"],["\u003cp\u003eThe document provides examples of overriding authentication for several \u003ccode\u003e*Client\u003c/code\u003e classes in the Monitoring service, including \u003ccode\u003eDashboardsServiceClient\u003c/code\u003e, \u003ccode\u003eMetricsScopesClient\u003c/code\u003e, and \u003ccode\u003eAlertPolicyServiceClient\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe latest version of the documentation is \u003ccode\u003e2.37.0-rc\u003c/code\u003e and a list of past versions starting from \u003ccode\u003e2.11.0\u003c/code\u003e is also provided.\u003c/p\u003e\n"],["\u003cp\u003eRefer to the "Best practices for managing service account keys" guide for more advanced details on managing authentication, as well as the "Authentication Components" section for more information on factory functions to create \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects.\u003c/p\u003e\n"]]],[],null,[]]
