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::texttospeech_v1::TextToSpeechClient(
google::cloud::texttospeech_v1::MakeTextToSpeechConnection(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 2025-04-17 UTC."],[[["The latest release candidate version for the C++ Text-to-Speech library is 2.37.0-rc, with a variety of previous stable versions available, ranging from 2.36.0 down to 2.11.0."],["By default, the client libraries use Application Default Credentials (ADC) for authenticating with Google Cloud Services, but this default can be overridden."],["You can override the default authentication by using `UnifiedCredentialsOption` and, for example, loading a service account key file, and this key file should follow the best practices for managing service account keys."],["The `Authentication Components` section provides additional information for creating `google::cloud::Credentials` objects."]]],[]]
