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, with available versions ranging from 2.15.1 to the latest release candidate 2.37.0-rc."],["By default, client libraries use Application Default Credentials (ADC) for authentication, but users can override this using the `UnifiedCredentialsOption`."],["The documentation includes a code example demonstrating how to load a service account key file to explicitly override authentication."],["Users are advised to consult the \"Best practices for managing service account keys\" guide for detailed information on managing service account keys."],["The \"Authentication Components\" documentation is available for further information on creating `google::cloud::Credentials` objects."]]],[]]
