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 authentication credentials for Google Cloud services, which typically use Application Default Credentials.\u003c/p\u003e\n"],["\u003cp\u003eThe latest release available is version 2.37.0-rc, and the content also covers versions ranging from 2.11.0 to 2.36.0, including 2.14.0 which is used as reference.\u003c/p\u003e\n"],["\u003cp\u003eOverriding authentication can be achieved by using \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, and the example provided shows how to load a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eThe code snippets linked provide examples of overriding authentication for \u003ccode\u003eiap_v1::IdentityAwareProxyAdminServiceClient\u003c/code\u003e and \u003ccode\u003eiap_v1::IdentityAwareProxyOAuthServiceClient\u003c/code\u003e in the 2.14.0 version.\u003c/p\u003e\n"],["\u003cp\u003eUsers are encouraged to review best practices for managing service account keys and to consult the Authentication Components documentation for further details on creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects.\u003c/p\u003e\n"]]],[],null,["Version 2.14.0keyboard_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/2.14.0/iap_v1_1_1IdentityAwareProxyAdminServiceClient-service-account-snippet)\n- [`iap_v1::IdentityAwareProxyOAuthServiceClient`](/cpp/docs/reference/iap/2.14.0/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."]]