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::cloudbuild_v1::CloudBuildClient(
google::cloud::cloudbuild_v1::MakeCloudBuildConnection(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 provides documentation for overriding default authentication credentials when using Google Cloud client libraries, specifically focusing on how to load a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eThe latest version of the documentation available is 2.37.0-rc, and there are multiple previous versions including 2.19.0, 2.15.1, and 2.11.0.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e allows users to override the default authentication, as shown in the provided example where a service account key file is explicitly loaded.\u003c/p\u003e\n"],["\u003cp\u003eExamples are provided for \u003ccode\u003ecloudbuild_v1::CloudBuildClient\u003c/code\u003e and \u003ccode\u003ecloudbuild_v2::RepositoryManagerClient\u003c/code\u003e classes to help with implementing authentication overrides.\u003c/p\u003e\n"],["\u003cp\u003eThe documentation advises consulting the "Best practices for managing service account keys" guide for more detailed information on managing service account keys.\u003c/p\u003e\n"]]],[],null,["Version 2.19.0keyboard_arrow_down\n\n- [2.42.0-rc (latest)](/cpp/docs/reference/cloudbuild/latest/cloudbuild-override-authentication)\n- [2.41.0](/cpp/docs/reference/cloudbuild/2.41.0/cloudbuild-override-authentication)\n- [2.40.0](/cpp/docs/reference/cloudbuild/2.40.0/cloudbuild-override-authentication)\n- [2.39.0](/cpp/docs/reference/cloudbuild/2.39.0/cloudbuild-override-authentication)\n- [2.38.0](/cpp/docs/reference/cloudbuild/2.38.0/cloudbuild-override-authentication)\n- [2.37.0](/cpp/docs/reference/cloudbuild/2.37.0/cloudbuild-override-authentication)\n- [2.36.0](/cpp/docs/reference/cloudbuild/2.36.0/cloudbuild-override-authentication)\n- [2.35.0](/cpp/docs/reference/cloudbuild/2.35.0/cloudbuild-override-authentication)\n- [2.34.0](/cpp/docs/reference/cloudbuild/2.34.0/cloudbuild-override-authentication)\n- [2.33.0](/cpp/docs/reference/cloudbuild/2.33.0/cloudbuild-override-authentication)\n- [2.32.0](/cpp/docs/reference/cloudbuild/2.32.0/cloudbuild-override-authentication)\n- [2.31.0](/cpp/docs/reference/cloudbuild/2.31.0/cloudbuild-override-authentication)\n- [2.30.0](/cpp/docs/reference/cloudbuild/2.30.0/cloudbuild-override-authentication)\n- [2.29.0](/cpp/docs/reference/cloudbuild/2.29.0/cloudbuild-override-authentication)\n- [2.28.0](/cpp/docs/reference/cloudbuild/2.28.0/cloudbuild-override-authentication)\n- [2.27.0](/cpp/docs/reference/cloudbuild/2.27.0/cloudbuild-override-authentication)\n- [2.26.0](/cpp/docs/reference/cloudbuild/2.26.0/cloudbuild-override-authentication)\n- [2.25.1](/cpp/docs/reference/cloudbuild/2.25.1/cloudbuild-override-authentication)\n- [2.24.0](/cpp/docs/reference/cloudbuild/2.24.0/cloudbuild-override-authentication)\n- [2.23.0](/cpp/docs/reference/cloudbuild/2.23.0/cloudbuild-override-authentication)\n- [2.22.1](/cpp/docs/reference/cloudbuild/2.22.1/cloudbuild-override-authentication)\n- [2.21.0](/cpp/docs/reference/cloudbuild/2.21.0/cloudbuild-override-authentication)\n- [2.20.0](/cpp/docs/reference/cloudbuild/2.20.0/cloudbuild-override-authentication)\n- [2.19.0](/cpp/docs/reference/cloudbuild/2.19.0/cloudbuild-override-authentication)\n- [2.18.0](/cpp/docs/reference/cloudbuild/2.18.0/cloudbuild-override-authentication)\n- [2.17.0](/cpp/docs/reference/cloudbuild/2.17.0/cloudbuild-override-authentication)\n- [2.16.0](/cpp/docs/reference/cloudbuild/2.16.0/cloudbuild-override-authentication)\n- [2.15.1](/cpp/docs/reference/cloudbuild/2.15.1/cloudbuild-override-authentication)\n- [2.14.0](/cpp/docs/reference/cloudbuild/2.14.0/cloudbuild-override-authentication)\n- [2.13.0](/cpp/docs/reference/cloudbuild/2.13.0/cloudbuild-override-authentication)\n- [2.12.0](/cpp/docs/reference/cloudbuild/2.12.0/cloudbuild-override-authentication)\n- [2.11.0](/cpp/docs/reference/cloudbuild/2.11.0/cloudbuild-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::cloudbuild_v1::CloudBuildClient(\n google::cloud::cloudbuild_v1::MakeCloudBuildConnection(options));\n }\n\nFollow these links to find examples for other `*Client` classes:\n\n- [`cloudbuild_v1::CloudBuildClient`](/cpp/docs/reference/cloudbuild/2.19.0/cloudbuild_v1_1_1CloudBuildClient-service-account-snippet)\n- [`cloudbuild_v2::RepositoryManagerClient`](/cpp/docs/reference/cloudbuild/2.19.0/cloudbuild_v2_1_1RepositoryManagerClient-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."]]