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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 authentication credentials when using Google Cloud client libraries, specifically for the Service Management API.\u003c/p\u003e\n"],["\u003cp\u003eThe latest version of the documentation available is 2.37.0-rc, and a history of previous versions is listed, ranging from 2.36.0 down to 2.11.0.\u003c/p\u003e\n"],["\u003cp\u003eClient libraries generally use Application Default Credentials, but this can be overridden using \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, as shown in an example using a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eThe example demonstrates how to load service account credentials from a key file and set them within the \u003ccode\u003egoogle::cloud::Options\u003c/code\u003e object for the \u003ccode\u003eServiceManagerClient\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eFor further information, the guide recommends referring to the "Best practices for managing service account keys" and the "Authentication Components" documentation.\u003c/p\u003e\n"]]],[],null,[]]
