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::workflows_executions_v1::ExecutionsClient(
google::cloud::workflows_executions_v1::MakeExecutionsConnection(
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 document details how to override the default Application Default Credentials (ADC) used by client libraries for authenticating with Google Cloud Services.\u003c/p\u003e\n"],["\u003cp\u003eYou can override the default credentials by using \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, and an example of loading a service account key file is provided.\u003c/p\u003e\n"],["\u003cp\u003eThe latest version is 2.37.0-rc, and the document provides versioned documentation from version 2.11.0 up to 2.37.0-rc, each with examples of overriding authentication.\u003c/p\u003e\n"],["\u003cp\u003eExamples for overriding authentication credentials can be found for \u003ccode\u003eworkflows_executions_v1::ExecutionsClient\u003c/code\u003e and \u003ccode\u003eworkflows_v1::WorkflowsClient\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe document directs the reader to an external document for best practices on managing service account keys.\u003c/p\u003e\n"]]],[],null,["Version 2.23.0keyboard_arrow_down\n\n- [2.42.0-rc (latest)](/cpp/docs/reference/workflows/latest/workflows-override-authentication)\n- [2.41.0](/cpp/docs/reference/workflows/2.41.0/workflows-override-authentication)\n- [2.40.0](/cpp/docs/reference/workflows/2.40.0/workflows-override-authentication)\n- [2.39.0](/cpp/docs/reference/workflows/2.39.0/workflows-override-authentication)\n- [2.38.0](/cpp/docs/reference/workflows/2.38.0/workflows-override-authentication)\n- [2.37.0](/cpp/docs/reference/workflows/2.37.0/workflows-override-authentication)\n- [2.36.0](/cpp/docs/reference/workflows/2.36.0/workflows-override-authentication)\n- [2.35.0](/cpp/docs/reference/workflows/2.35.0/workflows-override-authentication)\n- [2.34.0](/cpp/docs/reference/workflows/2.34.0/workflows-override-authentication)\n- [2.33.0](/cpp/docs/reference/workflows/2.33.0/workflows-override-authentication)\n- [2.32.0](/cpp/docs/reference/workflows/2.32.0/workflows-override-authentication)\n- [2.31.0](/cpp/docs/reference/workflows/2.31.0/workflows-override-authentication)\n- [2.30.0](/cpp/docs/reference/workflows/2.30.0/workflows-override-authentication)\n- [2.29.0](/cpp/docs/reference/workflows/2.29.0/workflows-override-authentication)\n- [2.28.0](/cpp/docs/reference/workflows/2.28.0/workflows-override-authentication)\n- [2.27.0](/cpp/docs/reference/workflows/2.27.0/workflows-override-authentication)\n- [2.26.0](/cpp/docs/reference/workflows/2.26.0/workflows-override-authentication)\n- [2.25.1](/cpp/docs/reference/workflows/2.25.1/workflows-override-authentication)\n- [2.24.0](/cpp/docs/reference/workflows/2.24.0/workflows-override-authentication)\n- [2.23.0](/cpp/docs/reference/workflows/2.23.0/workflows-override-authentication)\n- [2.22.1](/cpp/docs/reference/workflows/2.22.1/workflows-override-authentication)\n- [2.21.0](/cpp/docs/reference/workflows/2.21.0/workflows-override-authentication)\n- [2.20.0](/cpp/docs/reference/workflows/2.20.0/workflows-override-authentication)\n- [2.19.0](/cpp/docs/reference/workflows/2.19.0/workflows-override-authentication)\n- [2.18.0](/cpp/docs/reference/workflows/2.18.0/workflows-override-authentication)\n- [2.17.0](/cpp/docs/reference/workflows/2.17.0/workflows-override-authentication)\n- [2.16.0](/cpp/docs/reference/workflows/2.16.0/workflows-override-authentication)\n- [2.15.1](/cpp/docs/reference/workflows/2.15.1/workflows-override-authentication)\n- [2.14.0](/cpp/docs/reference/workflows/2.14.0/workflows-override-authentication)\n- [2.13.0](/cpp/docs/reference/workflows/2.13.0/workflows-override-authentication)\n- [2.12.0](/cpp/docs/reference/workflows/2.12.0/workflows-override-authentication)\n- [2.11.0](/cpp/docs/reference/workflows/2.11.0/workflows-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::workflows_executions_v1::ExecutionsClient(\n google::cloud::workflows_executions_v1::MakeExecutionsConnection(\n options));\n }\n\nFollow these links to find examples for other `*Client` classes:\n\n- [`workflows_executions_v1::ExecutionsClient`](/cpp/docs/reference/workflows/2.23.0/workflows_executions_v1_1_1ExecutionsClient-service-account-snippet)\n- [`workflows_v1::WorkflowsClient`](/cpp/docs/reference/workflows/2.23.0/workflows_v1_1_1WorkflowsClient-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."]]