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::automl_v1::AutoMlClient(
google::cloud::automl_v1::MakeAutoMlConnection(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"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14 UTC."],[[["\u003cp\u003eThis page details how to override default authentication credentials when using Google Cloud client libraries, particularly focusing on \u003ccode\u003eAutoMlClient\u003c/code\u003e and \u003ccode\u003ePredictionServiceClient\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe latest available version is \u003ccode\u003e2.37.0-rc\u003c/code\u003e, with multiple previous versions listed, ranging from \u003ccode\u003e2.36.0\u003c/code\u003e down to \u003ccode\u003e2.11.0\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eAuthentication can be overridden using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, as demonstrated with an example of loading a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eThe guide recommends using the \u003ca href=\"https://cloud.google.com/docs/authentication#adc\"\u003eApplication Default Credentials\u003c/a\u003e method, but also provides options on how to override this default if needed.\u003c/p\u003e\n"],["\u003cp\u003eAdditional resources, including "Best practices for managing service account keys" and "Authentication Components," are linked for more comprehensive information.\u003c/p\u003e\n"]]],[],null,[]]