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::storagecontrol_v2::StorageControlClient(
google::cloud::storagecontrol_v2::MakeStorageControlConnection(
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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 multiple older versions available dating back to 2.21.0.\u003c/p\u003e\n"],["\u003cp\u003eThe client libraries default to using Application Default Credentials (ADC) for authentication with Google Cloud Services.\u003c/p\u003e\n"],["\u003cp\u003eYou can override the default authentication by providing a \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, such as loading a service account key file, using \u003ccode\u003eMakeServiceAccountCredentials\u003c/code\u003e.\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,[]]
