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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 provides documentation for overriding default authentication credentials when interacting with Google Cloud Services, specifically using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe latest version documented on this page is 2.37.0-rc, while the oldest documented version is 2.11.0, and there are multiple versions between those, all with examples of authentication override.\u003c/p\u003e\n"],["\u003cp\u003eThe default authentication mechanism for client libraries is Application Default Credentials, which can be overridden by using the provided example code which demonstrates loading a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eExamples for overriding authentication credentials are provided for various \u003ccode\u003e*Client\u003c/code\u003e classes, including \u003ccode\u003eDashboardsServiceClient\u003c/code\u003e, \u003ccode\u003eMetricsScopesClient\u003c/code\u003e, \u003ccode\u003eAlertPolicyServiceClient\u003c/code\u003e, and others, all found within version 2.17.0.\u003c/p\u003e\n"],["\u003cp\u003eFor further details and best practices regarding service account keys, refer to the linked guide on managing service account keys and for more information on the factory functions to create credentials, refer to the Authentication Components page.\u003c/p\u003e\n"]]],[],null,[]]
