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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 provides documentation for overriding default authentication credentials when using Google Cloud C++ client libraries.\u003c/p\u003e\n"],["\u003cp\u003eThe latest release candidate version is 2.37.0-rc, with a range of versions from 2.11.0 up to 2.36.0 also available.\u003c/p\u003e\n"],["\u003cp\u003eAuthentication override can be achieved by providing the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, such as explicitly loading a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eExamples for \u003ccode\u003eautoml_v1::AutoMlClient\u003c/code\u003e and \u003ccode\u003eautoml_v1::PredictionServiceClient\u003c/code\u003e classes are available to demonstrate this override.\u003c/p\u003e\n"],["\u003cp\u003eThe best practices for service account key management are linked for more in depth knowledge on this topic, as is a link to authentication components.\u003c/p\u003e\n"]]],[],null,[]]
