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::batch_v1::BatchServiceClient(
google::cloud::batch_v1::MakeBatchServiceConnection(options));
}
[[["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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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\u003eThe latest version available is 2.37.0-rc, with a history of versions back to 2.11.0, all related to batch authentication overrides.\u003c/p\u003e\n"],["\u003cp\u003eBy default, the client libraries utilize Application Default Credentials for Google Cloud Services authentication, but this can be overridden.\u003c/p\u003e\n"],["\u003cp\u003eYou can override default authentication by supplying the UnifiedCredentialsOption, like explicitly loading a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eFor best practices on managing service account keys, refer to the provided guide.\u003c/p\u003e\n"],["\u003cp\u003eMore information about creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects can be found in the Authentication Components documentation.\u003c/p\u003e\n"]]],[],null,[]]
