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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 documents how to override the default Application Default Credentials (ADC) used by the client libraries for authenticating with Google Cloud Services.\u003c/p\u003e\n"],["\u003cp\u003eYou can override the default credentials by providing the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e and using a service account key file, as demonstrated in the provided example.\u003c/p\u003e\n"],["\u003cp\u003eThe latest release candidate for the Dataproc library is version 2.37.0-rc, and numerous prior versions are available, with the earliest documented being version 2.11.0.\u003c/p\u003e\n"],["\u003cp\u003eExamples are provided for various \u003ccode\u003e*Client\u003c/code\u003e classes within the \u003ccode\u003edataproc_v1\u003c/code\u003e namespace, including \u003ccode\u003eAutoscalingPolicyServiceClient\u003c/code\u003e, \u003ccode\u003eBatchControllerClient\u003c/code\u003e, and \u003ccode\u003eClusterControllerClient\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe provided links reference the guide for managing service account keys as well as the authentication component for more information on creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects.\u003c/p\u003e\n"]]],[],null,[]]
