Unless otherwise configured, the client libraries use Application Default Credentials 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 The 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::dataproc_v1::AutoscalingPolicyServiceClient(
google::cloud::dataproc_v1::MakeAutoscalingPolicyServiceConnection(
options));
}
Follow these links to find examples for other *Client classes:
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14 UTC."],[[["\u003cp\u003eThis page provides documentation for overriding default authentication credentials when using Google Cloud client libraries, specifically focusing on the Dataproc service.\u003c/p\u003e\n"],["\u003cp\u003eThe latest version of the documentation is 2.37.0-rc, but the page includes a comprehensive list of versions from 2.11.0 up to the latest, with each version having its own set of documentation pages.\u003c/p\u003e\n"],["\u003cp\u003eThe documentation details how to override the default authentication using \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e by loading a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eExamples are provided for several Dataproc \u003ccode\u003e*Client\u003c/code\u003e classes, including \u003ccode\u003eAutoscalingPolicyServiceClient\u003c/code\u003e, \u003ccode\u003eBatchControllerClient\u003c/code\u003e, \u003ccode\u003eClusterControllerClient\u003c/code\u003e, \u003ccode\u003eJobControllerClient\u003c/code\u003e, and \u003ccode\u003eWorkflowTemplateServiceClient\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe page includes a link to the "Best practices for managing service account keys" guide and the "Authentication Components" documentation for further information on authentication and credentials.\u003c/p\u003e\n"]]],[],null,[]]
