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::speech_v1::AdaptationClient(
google::cloud::speech_v1::MakeAdaptationConnection(options));
}
Follow these links to find examples for other *Client classes:
[[["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 2025-08-01 UTC."],[[["The latest version available is 2.37.0-rc, with numerous older versions like 2.36.0, 2.35.0, and going all the way back to version 2.11.0 also accessible."],["By default, client libraries use Application Default Credentials, however you can override them using the UnifiedCredentialsOption for specific scenarios."],["An example of overriding default credentials includes loading a service account key file, as shown in the provided code snippet."],["You can find similar examples on overriding credentials for other client classes such as `speech_v1::AdaptationClient`, `speech_v1::SpeechClient`, and `speech_v2::SpeechClient`."],["The Authentication Components documentation provides more detailed information about creating `google::cloud::Credentials` objects."]]],[]]
