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::secretmanager_v1::SecretManagerServiceClient(
google::cloud::secretmanager_v1::MakeSecretManagerServiceConnection(
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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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\u003eThis page details how to override the default authentication credentials used by client libraries when interacting with Google Cloud Services.\u003c/p\u003e\n"],["\u003cp\u003eThe latest version of the documentation available on this page is 2.37.0-rc, while the oldest available version is 2.10.1.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e allows users to customize authentication, such as explicitly loading a service account key file as demonstrated in the provided example code.\u003c/p\u003e\n"],["\u003cp\u003eUsers can find more information about factory functions for creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects in the Authentication Components section.\u003c/p\u003e\n"],["\u003cp\u003eThe default authentication method is Application Default Credentials, and the provided method is an override, with users needing to refer to best practices to properly manage these service account keys.\u003c/p\u003e\n"]]],[],null,[]]
