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::servicemanagement_v1::ServiceManagerClient(
google::cloud::servicemanagement_v1::MakeServiceManagerConnection(
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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 focusing on C++ implementations.\u003c/p\u003e\n"],["\u003cp\u003eThe content covers a range of versions, from 2.11.0 up to the latest release candidate 2.37.0-rc, each providing links to their respective documentation.\u003c/p\u003e\n"],["\u003cp\u003eThe primary method for overriding credentials involves using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e and demonstrating how to load a service account key file, showing an easy to understand example.\u003c/p\u003e\n"],["\u003cp\u003eThe documentation advises users to refer to the "Best practices for managing service account keys" guide for secure handling of credentials.\u003c/p\u003e\n"],["\u003cp\u003eThe page also links to the "Authentication Components" section for further information on creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects.\u003c/p\u003e\n"]]],[],null,[]]
