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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 provides documentation for overriding default authentication credentials when using Google Cloud client libraries, specifically for the Secret Manager service.\u003c/p\u003e\n"],["\u003cp\u003eThe most recent release candidate is version 2.37.0-rc, with the page also listing numerous prior versions down to 2.10.1.\u003c/p\u003e\n"],["\u003cp\u003eAuthentication can be overridden using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, as illustrated by an example of loading a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eThe provided code sample shows the process of manually loading a service account key file for authentication, using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e and \u003ccode\u003eMakeServiceAccountCredentials\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eFor additional details on creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects and best practices for managing service account keys, users are encouraged to see the linked documents.\u003c/p\u003e\n"]]],[],null,[]]
