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 the C++ client libraries.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e can be used to override the default credentials, such as explicitly loading a service account key file as demonstrated in the example.\u003c/p\u003e\n"],["\u003cp\u003eMultiple versions of documentation for monitoring services are available, ranging from version 2.11.0 up to the latest release candidate 2.37.0-rc.\u003c/p\u003e\n"],["\u003cp\u003eExamples are provided for various \u003ccode\u003e*Client\u003c/code\u003e classes, demonstrating how to implement the service account key override including \u003ccode\u003eDashboardsServiceClient\u003c/code\u003e, \u003ccode\u003eMetricsScopesClient\u003c/code\u003e, and others.\u003c/p\u003e\n"],["\u003cp\u003eRefer to the "Best practices for managing service account keys" guide for more advanced details on managing these keys and the "Authentication Components" page for more information on creating \u003ccode\u003eCredentials\u003c/code\u003e objects.\u003c/p\u003e\n"]]],[],null,["Version 2.28.0keyboard_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/2.28.0/monitoring_dashboard_v1_1_1DashboardsServiceClient-service-account-snippet)\n- [`monitoring_metricsscope_v1::MetricsScopesClient`](/cpp/docs/reference/monitoring/2.28.0/monitoring_metricsscope_v1_1_1MetricsScopesClient-service-account-snippet)\n- [`monitoring_v3::AlertPolicyServiceClient`](/cpp/docs/reference/monitoring/2.28.0/monitoring_v3_1_1AlertPolicyServiceClient-service-account-snippet)\n- [`monitoring_v3::GroupServiceClient`](/cpp/docs/reference/monitoring/2.28.0/monitoring_v3_1_1GroupServiceClient-service-account-snippet)\n- [`monitoring_v3::MetricServiceClient`](/cpp/docs/reference/monitoring/2.28.0/monitoring_v3_1_1MetricServiceClient-service-account-snippet)\n- [`monitoring_v3::NotificationChannelServiceClient`](/cpp/docs/reference/monitoring/2.28.0/monitoring_v3_1_1NotificationChannelServiceClient-service-account-snippet)\n- [`monitoring_v3::QueryServiceClient`](/cpp/docs/reference/monitoring/2.28.0/monitoring_v3_1_1QueryServiceClient-service-account-snippet)\n- [`monitoring_v3::ServiceMonitoringServiceClient`](/cpp/docs/reference/monitoring/2.28.0/monitoring_v3_1_1ServiceMonitoringServiceClient-service-account-snippet)\n- [`monitoring_v3::SnoozeServiceClient`](/cpp/docs/reference/monitoring/2.28.0/monitoring_v3_1_1SnoozeServiceClient-service-account-snippet)\n- [`monitoring_v3::UptimeCheckServiceClient`](/cpp/docs/reference/monitoring/2.28.0/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."]]