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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 details 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 using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, demonstrated here with an example of loading a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eThe document provides links to examples demonstrating credential overriding for various \u003ccode\u003e*Client\u003c/code\u003e classes such as \u003ccode\u003eAutoscalingPolicyServiceClient\u003c/code\u003e, \u003ccode\u003eBatchControllerClient\u003c/code\u003e, and \u003ccode\u003eClusterControllerClient\u003c/code\u003e, all within the dataproc_v1 namespace.\u003c/p\u003e\n"],["\u003cp\u003eIt is recommended to look over the best practices guide for managing service account keys for more information on this topic, and check out the Authentication Components page for further insight on the factory functions.\u003c/p\u003e\n"],["\u003cp\u003eThe content includes a list of the available versions for the content ranging from version 2.11.0 to 2.37.0-rc.\u003c/p\u003e\n"]]],[],null,[]]
