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::iap_v1::IdentityAwareProxyAdminServiceClient(
google::cloud::iap_v1::MakeIdentityAwareProxyAdminServiceConnection(
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 done by providing a \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe latest release candidate version for this content is 2.37.0-rc, while the stable, currently presented version is 2.15.1.\u003c/p\u003e\n"],["\u003cp\u003eAn example of overriding authentication using a service account key file is provided, demonstrating the use of \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, \u003ccode\u003eMakeServiceAccountCredentials\u003c/code\u003e, and how to load the keyfile contents.\u003c/p\u003e\n"],["\u003cp\u003eExamples for \u003ccode\u003eiap_v1::IdentityAwareProxyAdminServiceClient\u003c/code\u003e and \u003ccode\u003eiap_v1::IdentityAwareProxyOAuthServiceClient\u003c/code\u003e classes are linked, demonstrating the use of service accounts.\u003c/p\u003e\n"],["\u003cp\u003eThe documentation also provides a link to best practices for managing service account keys and a link to the Authentication Components guide for creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects.\u003c/p\u003e\n"]]],[],null,["Version 2.15.1keyboard_arrow_down\n\n- [2.42.0-rc (latest)](/cpp/docs/reference/iap/latest/iap-override-authentication)\n- [2.41.0](/cpp/docs/reference/iap/2.41.0/iap-override-authentication)\n- [2.40.0](/cpp/docs/reference/iap/2.40.0/iap-override-authentication)\n- [2.39.0](/cpp/docs/reference/iap/2.39.0/iap-override-authentication)\n- [2.38.0](/cpp/docs/reference/iap/2.38.0/iap-override-authentication)\n- [2.37.0](/cpp/docs/reference/iap/2.37.0/iap-override-authentication)\n- [2.36.0](/cpp/docs/reference/iap/2.36.0/iap-override-authentication)\n- [2.35.0](/cpp/docs/reference/iap/2.35.0/iap-override-authentication)\n- [2.34.0](/cpp/docs/reference/iap/2.34.0/iap-override-authentication)\n- [2.33.0](/cpp/docs/reference/iap/2.33.0/iap-override-authentication)\n- [2.32.0](/cpp/docs/reference/iap/2.32.0/iap-override-authentication)\n- [2.31.0](/cpp/docs/reference/iap/2.31.0/iap-override-authentication)\n- [2.30.0](/cpp/docs/reference/iap/2.30.0/iap-override-authentication)\n- [2.29.0](/cpp/docs/reference/iap/2.29.0/iap-override-authentication)\n- [2.28.0](/cpp/docs/reference/iap/2.28.0/iap-override-authentication)\n- [2.27.0](/cpp/docs/reference/iap/2.27.0/iap-override-authentication)\n- [2.26.0](/cpp/docs/reference/iap/2.26.0/iap-override-authentication)\n- [2.25.1](/cpp/docs/reference/iap/2.25.1/iap-override-authentication)\n- [2.24.0](/cpp/docs/reference/iap/2.24.0/iap-override-authentication)\n- [2.23.0](/cpp/docs/reference/iap/2.23.0/iap-override-authentication)\n- [2.22.1](/cpp/docs/reference/iap/2.22.1/iap-override-authentication)\n- [2.21.0](/cpp/docs/reference/iap/2.21.0/iap-override-authentication)\n- [2.20.0](/cpp/docs/reference/iap/2.20.0/iap-override-authentication)\n- [2.19.0](/cpp/docs/reference/iap/2.19.0/iap-override-authentication)\n- [2.18.0](/cpp/docs/reference/iap/2.18.0/iap-override-authentication)\n- [2.17.0](/cpp/docs/reference/iap/2.17.0/iap-override-authentication)\n- [2.16.0](/cpp/docs/reference/iap/2.16.0/iap-override-authentication)\n- [2.15.1](/cpp/docs/reference/iap/2.15.1/iap-override-authentication)\n- [2.14.0](/cpp/docs/reference/iap/2.14.0/iap-override-authentication)\n- [2.13.0](/cpp/docs/reference/iap/2.13.0/iap-override-authentication)\n- [2.12.0](/cpp/docs/reference/iap/2.12.0/iap-override-authentication)\n- [2.11.0](/cpp/docs/reference/iap/2.11.0/iap-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::iap_v1::IdentityAwareProxyAdminServiceClient(\n google::cloud::iap_v1::MakeIdentityAwareProxyAdminServiceConnection(\n options));\n }\n\nFollow these links to find examples for other `*Client` classes:\n\n- [`iap_v1::IdentityAwareProxyAdminServiceClient`](/cpp/docs/reference/iap/2.15.1/iap_v1_1_1IdentityAwareProxyAdminServiceClient-service-account-snippet)\n- [`iap_v1::IdentityAwareProxyOAuthServiceClient`](/cpp/docs/reference/iap/2.15.1/iap_v1_1_1IdentityAwareProxyOAuthServiceClient-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."]]