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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 available version is 2.37.0-rc, with numerous other versions, including the current version 2.21.0, also available for reference.\u003c/p\u003e\n"],["\u003cp\u003eThe default authentication for client libraries uses Application Default Credentials, but this can be overridden when necessary.\u003c/p\u003e\n"],["\u003cp\u003eYou can override the default credentials using \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, such as explicitly loading a service account key file, as demonstrated in the provided code example.\u003c/p\u003e\n"],["\u003cp\u003eFor detailed information on creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects, you can refer to the Authentication Components documentation.\u003c/p\u003e\n"],["\u003cp\u003eService account key management is vital, and you can consult the best practices guide for service account keys for more information on this.\u003c/p\u003e\n"]]],[],null,[]]
