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::policysimulator_v1::SimulatorClient(
google::cloud::policysimulator_v1::MakeSimulatorConnection(options));
}
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-03-21 UTC."],[[["This page provides documentation for the Policy Simulator, specifically detailing how to override default authentication credentials when using the C++ client libraries."],["The latest version available is 2.37.0-rc, and documentation spans back to version 2.15.1, with a variety of versions in between."],["The default authentication method is Application Default Credentials, but you can use the `UnifiedCredentialsOption` to override it."],["A practical code example demonstrates how to load and utilize a service account key file to authenticate, suggesting you refer to the best practices guide for managing service account keys."],["The page provides a link to the Authentication Components for more information on creating `google::cloud::Credentials` objects."]]],[]]
