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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 using Google Cloud client libraries, which typically rely on Application Default Credentials.\u003c/p\u003e\n"],["\u003cp\u003eUsers can override the default authentication by providing the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, such as explicitly loading a service account key file as demonstrated in the example code.\u003c/p\u003e\n"],["\u003cp\u003eThe document lists several \u003ccode\u003e*Client\u003c/code\u003e classes with links to examples showing how to use service account keys for each client, including \u003ccode\u003eDashboardsServiceClient\u003c/code\u003e, \u003ccode\u003eMetricsScopesClient\u003c/code\u003e, and various \u003ccode\u003emonitoring_v3\u003c/code\u003e clients.\u003c/p\u003e\n"],["\u003cp\u003eThe provided example illustrates the procedure to override authentication by reading a service account key file's contents and setting it in the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, allowing for the creation of authenticated client objects.\u003c/p\u003e\n"],["\u003cp\u003eThe content on this page is available in multiple versions, starting from \u003ccode\u003e2.11.0\u003c/code\u003e to the latest release candidate \u003ccode\u003e2.37.0-rc\u003c/code\u003e.\u003c/p\u003e\n"]]],[],null,[]]
