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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 within the context of the Dataproc service.\u003c/p\u003e\n"],["\u003cp\u003eThe client libraries typically rely on Application Default Credentials (ADC) for authentication, but users can override this by utilizing the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eAn example is provided demonstrating how to explicitly load a service account key file to manage authentication.\u003c/p\u003e\n"],["\u003cp\u003eVersion specific documentation is available, ranging from the latest release candidate version \u003ccode\u003e2.37.0-rc\u003c/code\u003e down to version \u003ccode\u003e2.11.0\u003c/code\u003e, with version \u003ccode\u003e2.26.0\u003c/code\u003e being the version used for the examples on the page.\u003c/p\u003e\n"],["\u003cp\u003eThere are links provided to code snippets showing examples for several different \u003ccode\u003e*Client\u003c/code\u003e classes, all using version \u003ccode\u003e2.26.0\u003c/code\u003e, as well as a link to the best practices for managing service account keys and the authentication components.\u003c/p\u003e\n"]]],[],null,[]]
