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::serviceusage_v1::ServiceUsageClient(
google::cloud::serviceusage_v1::MakeServiceUsageConnection(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 2025-05-07 UTC."],[[["This webpage provides documentation for the Google Cloud C++ client library's Service Usage API, covering versions from 2.11.0 up to the release candidate 2.37.0-rc."],["The latest version of the Service Usage API that is not a release candidate is 2.36.0."],["The default authentication method is Application Default Credentials, but developers can override this by using the `UnifiedCredentialsOption`."],["The example code shows how to use `UnifiedCredentialsOption` to explicitly load a service account key file for authentication, in cases where the default Application Default Credentials are not sufficient."],["For more information about creating `google::cloud::Credentials` objects and best practices for managing service account keys, refer to the Authentication Components guide and the service account keys management guide."]]],[]]
