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::language_v1::LanguageServiceClient(
google::cloud::language_v1::MakeLanguageServiceConnection(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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 the default Application Default Credentials (ADC) for authenticating with Google Cloud Services.\u003c/p\u003e\n"],["\u003cp\u003eThe latest release candidate version is 2.37.0-rc, and the content lists all versions from this to 2.11.0.\u003c/p\u003e\n"],["\u003cp\u003eUsers can override the default authentication by using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e and loading a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eExamples for overriding credentials using service account key files are available for \u003ccode\u003elanguage_v1::LanguageServiceClient\u003c/code\u003e and \u003ccode\u003elanguage_v2::LanguageServiceClient\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eFor more information on managing service account keys and creating credentials objects, the page provides links to the best practices guide and the Authentication Components documentation, respectively.\u003c/p\u003e\n"]]],[],null,[]]
