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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 documented is 2.37.0-rc, with versions dating back to 2.11.0, all available in the documentation.\u003c/p\u003e\n"],["\u003cp\u003eThe example code provided demonstrates how to load a service account key file and utilize the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e to override the default Application Default Credentials (ADC) authentication.\u003c/p\u003e\n"],["\u003cp\u003eLinks to examples for various \u003ccode\u003e*Client\u003c/code\u003e classes within the \u003ccode\u003edataproc_v1\u003c/code\u003e namespace, such as \u003ccode\u003eAutoscalingPolicyServiceClient\u003c/code\u003e, \u003ccode\u003eBatchControllerClient\u003c/code\u003e, and others, are listed for version 2.19.0.\u003c/p\u003e\n"],["\u003cp\u003eThe best practices guide for managing service account keys is linked, along with a link to the Authentication Components for more details on creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects.\u003c/p\u003e\n"]]],[],null,[]]
