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::optimization_v1::FleetRoutingClient(
google::cloud::optimization_v1::MakeFleetRoutingConnection(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 2025-04-02 UTC."],[[["This page provides documentation for overriding default authentication credentials when using Google Cloud C++ client libraries, with a focus on the `optimization` component."],["The latest release candidate version is 2.37.0-rc, and the page lists previous versions down to 2.11.0, with links for each version to the relevant documentation."],["Overriding default credentials can be achieved by using the `UnifiedCredentialsOption`, which allows you to explicitly load credentials, such as a service account key file, with an example in code."],["The user is recommended to use the link provided to the best practice guide for managing service account keys, as this is only an example of how you could do this."],["The user is also referred to the Authentication Components page, which provides further information on factory functions to create `google::cloud::Credentials` objects."]]],[]]
