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, which is sometimes necessary.\u003c/p\u003e\n"],["\u003cp\u003eYou can override the default credentials by providing the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e and an example is shown on how to load a service account key file, as well as its implementations.\u003c/p\u003e\n"],["\u003cp\u003eLinks are provided to examples for various \u003ccode\u003e*Client\u003c/code\u003e classes such as \u003ccode\u003eDashboardsServiceClient\u003c/code\u003e, \u003ccode\u003eMetricsScopesClient\u003c/code\u003e, and others for version \u003ccode\u003e2.11.0\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe latest release candidate is version \u003ccode\u003e2.37.0-rc\u003c/code\u003e, and all of the listed version numbers range from \u003ccode\u003e2.11.0\u003c/code\u003e to \u003ccode\u003e2.36.0\u003c/code\u003e, providing support for various versions.\u003c/p\u003e\n"],["\u003cp\u003eThe provided method for overriding authentication is a simple example, and users are encouraged to consult the best practices guide for managing service account keys for more complex usage.\u003c/p\u003e\n"]]],[],null,["Version 2.11.0keyboard_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/2.11.0/monitoring_dashboard_v1_1_1DashboardsServiceClient-service-account-snippet)\n- [`monitoring_metricsscope_v1::MetricsScopesClient`](/cpp/docs/reference/monitoring/2.11.0/monitoring_metricsscope_v1_1_1MetricsScopesClient-service-account-snippet)\n- [`monitoring_v3::AlertPolicyServiceClient`](/cpp/docs/reference/monitoring/2.11.0/monitoring_v3_1_1AlertPolicyServiceClient-service-account-snippet)\n- [`monitoring_v3::GroupServiceClient`](/cpp/docs/reference/monitoring/2.11.0/monitoring_v3_1_1GroupServiceClient-service-account-snippet)\n- [`monitoring_v3::MetricServiceClient`](/cpp/docs/reference/monitoring/2.11.0/monitoring_v3_1_1MetricServiceClient-service-account-snippet)\n- [`monitoring_v3::NotificationChannelServiceClient`](/cpp/docs/reference/monitoring/2.11.0/monitoring_v3_1_1NotificationChannelServiceClient-service-account-snippet)\n- [`monitoring_v3::QueryServiceClient`](/cpp/docs/reference/monitoring/2.11.0/monitoring_v3_1_1QueryServiceClient-service-account-snippet)\n- [`monitoring_v3::ServiceMonitoringServiceClient`](/cpp/docs/reference/monitoring/2.11.0/monitoring_v3_1_1ServiceMonitoringServiceClient-service-account-snippet)\n- [`monitoring_v3::UptimeCheckServiceClient`](/cpp/docs/reference/monitoring/2.11.0/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."]]