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 client libraries."],["The most recent release candidate is version 2.37.0-rc, and the documentation covers versions down to 2.15.1, including a link to each version."],["Overriding default credentials can be achieved by providing the `UnifiedCredentialsOption`, such as loading a service account key file as shown in the provided code example."],["The default authentication method used by the client libraries is Application Default Credentials unless otherwise configured, meaning a manual override is necessary in some cases."],["For detailed information on creating `google::cloud::Credentials` objects, the \"Authentication Components\" link is provided, in addition to the \"Best practices for managing service account keys\" guide."]]],[]]
