Unless otherwise configured, the client libraries useApplication Default Credentialsto 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 theUnifiedCredentialsOptionThe 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*Clientclasses:
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-09-04 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,["Version 2.19.0keyboard_arrow_down\n\n- [2.42.0-rc (latest)](/cpp/docs/reference/monitoring/latest/monitoring-override-authentication)\n- [2.41.0](/cpp/docs/reference/monitoring/2.41.0/monitoring-override-authentication)\n- [2.40.0](/cpp/docs/reference/monitoring/2.40.0/monitoring-override-authentication)\n- [2.39.0](/cpp/docs/reference/monitoring/2.39.0/monitoring-override-authentication)\n- [2.38.0](/cpp/docs/reference/monitoring/2.38.0/monitoring-override-authentication)\n- [2.37.0](/cpp/docs/reference/monitoring/2.37.0/monitoring-override-authentication)\n- [2.36.0](/cpp/docs/reference/monitoring/2.36.0/monitoring-override-authentication)\n- [2.35.0](/cpp/docs/reference/monitoring/2.35.0/monitoring-override-authentication)\n- [2.34.0](/cpp/docs/reference/monitoring/2.34.0/monitoring-override-authentication)\n- [2.33.0](/cpp/docs/reference/monitoring/2.33.0/monitoring-override-authentication)\n- [2.32.0](/cpp/docs/reference/monitoring/2.32.0/monitoring-override-authentication)\n- [2.31.0](/cpp/docs/reference/monitoring/2.31.0/monitoring-override-authentication)\n- [2.30.0](/cpp/docs/reference/monitoring/2.30.0/monitoring-override-authentication)\n- [2.29.0](/cpp/docs/reference/monitoring/2.29.0/monitoring-override-authentication)\n- [2.28.0](/cpp/docs/reference/monitoring/2.28.0/monitoring-override-authentication)\n- [2.27.0](/cpp/docs/reference/monitoring/2.27.0/monitoring-override-authentication)\n- [2.26.0](/cpp/docs/reference/monitoring/2.26.0/monitoring-override-authentication)\n- [2.25.1](/cpp/docs/reference/monitoring/2.25.1/monitoring-override-authentication)\n- [2.24.0](/cpp/docs/reference/monitoring/2.24.0/monitoring-override-authentication)\n- [2.23.0](/cpp/docs/reference/monitoring/2.23.0/monitoring-override-authentication)\n- [2.22.1](/cpp/docs/reference/monitoring/2.22.1/monitoring-override-authentication)\n- [2.21.0](/cpp/docs/reference/monitoring/2.21.0/monitoring-override-authentication)\n- [2.20.0](/cpp/docs/reference/monitoring/2.20.0/monitoring-override-authentication)\n- [2.19.0](/cpp/docs/reference/monitoring/2.19.0/monitoring-override-authentication)\n- [2.18.0](/cpp/docs/reference/monitoring/2.18.0/monitoring-override-authentication)\n- [2.17.0](/cpp/docs/reference/monitoring/2.17.0/monitoring-override-authentication)\n- [2.16.0](/cpp/docs/reference/monitoring/2.16.0/monitoring-override-authentication)\n- [2.15.1](/cpp/docs/reference/monitoring/2.15.1/monitoring-override-authentication)\n- [2.14.0](/cpp/docs/reference/monitoring/2.14.0/monitoring-override-authentication)\n- [2.13.0](/cpp/docs/reference/monitoring/2.13.0/monitoring-override-authentication)\n- [2.12.0](/cpp/docs/reference/monitoring/2.12.0/monitoring-override-authentication)\n- [2.11.0](/cpp/docs/reference/monitoring/2.11.0/monitoring-override-authentication) \n\nHow to Override the Authentication Credentials\n==============================================\n\nUnless otherwise configured, the client libraries use [Application Default Credentials](https://cloud.google.com/docs/authentication#adc) 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](https://cloud.google.com/cpp/docs/reference/common/latest/structgoogle_1_1cloud_1_1UnifiedCredentialsOption.html) The following example shows how to explicitly load a service account key file: \n\n [](std::string const& keyfile) {\n auto is = std::ifstream(keyfile);\n is.exceptions(std::ios::badbit); // Minimal error handling in examples\n auto contents = std::string(std::istreambuf_iterator\u003cchar\u003e(is.rdbuf()), {});\n auto options =\n google::cloud::Options{}.set\u003cgoogle::cloud::UnifiedCredentialsOption\u003e(\n google::cloud::MakeServiceAccountCredentials(contents));\n return google::cloud::monitoring_dashboard_v1::DashboardsServiceClient(\n google::cloud::monitoring_dashboard_v1::MakeDashboardsServiceConnection(\n options));\n }\n\nFollow these links to find examples for other `*Client` classes:\n\n- [`monitoring_dashboard_v1::DashboardsServiceClient`](/cpp/docs/reference/monitoring/2.19.0/monitoring_dashboard_v1_1_1DashboardsServiceClient-service-account-snippet)\n- [`monitoring_metricsscope_v1::MetricsScopesClient`](/cpp/docs/reference/monitoring/2.19.0/monitoring_metricsscope_v1_1_1MetricsScopesClient-service-account-snippet)\n- [`monitoring_v3::AlertPolicyServiceClient`](/cpp/docs/reference/monitoring/2.19.0/monitoring_v3_1_1AlertPolicyServiceClient-service-account-snippet)\n- [`monitoring_v3::GroupServiceClient`](/cpp/docs/reference/monitoring/2.19.0/monitoring_v3_1_1GroupServiceClient-service-account-snippet)\n- [`monitoring_v3::MetricServiceClient`](/cpp/docs/reference/monitoring/2.19.0/monitoring_v3_1_1MetricServiceClient-service-account-snippet)\n- [`monitoring_v3::NotificationChannelServiceClient`](/cpp/docs/reference/monitoring/2.19.0/monitoring_v3_1_1NotificationChannelServiceClient-service-account-snippet)\n- [`monitoring_v3::QueryServiceClient`](/cpp/docs/reference/monitoring/2.19.0/monitoring_v3_1_1QueryServiceClient-service-account-snippet)\n- [`monitoring_v3::ServiceMonitoringServiceClient`](/cpp/docs/reference/monitoring/2.19.0/monitoring_v3_1_1ServiceMonitoringServiceClient-service-account-snippet)\n- [`monitoring_v3::SnoozeServiceClient`](/cpp/docs/reference/monitoring/2.19.0/monitoring_v3_1_1SnoozeServiceClient-service-account-snippet)\n- [`monitoring_v3::UptimeCheckServiceClient`](/cpp/docs/reference/monitoring/2.19.0/monitoring_v3_1_1UptimeCheckServiceClient-service-account-snippet)\n\nKeep in mind that we chose this as an example because it is relatively easy to understand. Consult the [Best practices for managing service account keys](https://cloud.google.com/iam/docs/best-practices-for-managing-service-account-keys) guide for more details.\n\n###### See Also\n\n[Authentication Components](https://cloud.google.com/cpp/docs/reference/common/latest/group__guac.html) - for more information on the factory functions to create [`google::cloud::Credentials`](https://cloud.google.com/cpp/docs/reference/common/latest/classgoogle_1_1cloud_1_1Credentials.html) objects."]]