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."],[[["This page provides documentation for various versions of the Text-to-Speech C++ client library, ranging from version 2.11.0 up to the latest release candidate, 2.37.0-rc."],["The default authentication method for the client libraries is Application Default Credentials, but this can be overridden if necessary."],["Overriding the default authentication can be achieved by using the `UnifiedCredentialsOption` to provide an alternative set of credentials."],["The provided example demonstrates how to override authentication by explicitly loading a service account key file."],["There is a provided link to the [Best practices for managing service account keys](https://cloud.google.com/iam/docs/best-practices-for-managing-service-account-keys) guide, as well as a link to [Authentication Components](https://cloud.google.com/cpp/docs/reference/common/latest/group__guac.html) for more details."]]],[]]
