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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-07-09 UTC."],[[["This page provides documentation for overriding default authentication credentials when using Google Cloud client libraries, specifically within the context of the Dataproc service."],["The client libraries typically use Application Default Credentials, but you can override this by utilizing the `UnifiedCredentialsOption` and providing your own credentials, such as a service account key file."],["The latest release candidate for the Dataproc C++ library is version 2.37.0-rc, with many other previous versions listed ranging back to 2.11.0, all related to Dataproc authentication."],["Examples are provided to demonstrate how to explicitly load service account key files for various `*Client` classes, such as `AutoscalingPolicyServiceClient` and `BatchControllerClient`."],["For further details and best practices regarding service account key management, refer to the linked \"Best practices for managing service account keys\" guide, as well as the authentication components documentation for the creation of `google::cloud::Credentials` objects."]]],[]]
