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\u003eThe latest release candidate version is 2.37.0-rc, and numerous previous versions are also documented, ranging down to 2.11.0.\u003c/p\u003e\n"],["\u003cp\u003eClient libraries typically use Application Default Credentials for Google Cloud service authentication, but this can be overridden.\u003c/p\u003e\n"],["\u003cp\u003eOverriding default credentials can be accomplished using \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, as demonstrated by explicitly loading a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eExamples for other \u003ccode\u003e*Client\u003c/code\u003e classes, specifically \u003ccode\u003eiap_v1::IdentityAwareProxyAdminServiceClient\u003c/code\u003e and \u003ccode\u003eiap_v1::IdentityAwareProxyOAuthServiceClient\u003c/code\u003e, are available through provided links.\u003c/p\u003e\n"],["\u003cp\u003eThe document points the user to the "Best practices for managing service account keys" and the "Authentication Components" pages for more details.\u003c/p\u003e\n"]]],[],null,["Version 2.21.0keyboard_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/2.21.0/iap_v1_1_1IdentityAwareProxyAdminServiceClient-service-account-snippet)\n- [`iap_v1::IdentityAwareProxyOAuthServiceClient`](/cpp/docs/reference/iap/2.21.0/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."]]