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::tpu_v1::TpuClient(
google::cloud::tpu_v1::MakeTpuConnection(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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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\u003eThe page provides documentation for overriding default authentication credentials when using Google Cloud client libraries, which normally use Application Default Credentials.\u003c/p\u003e\n"],["\u003cp\u003eThe most recent version available for the TPU override authentication documentation is 2.37.0-rc, while version 2.12.0 is shown on the page.\u003c/p\u003e\n"],["\u003cp\u003eThe documentation explains how to explicitly load a service account key file using \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e and \u003ccode\u003eMakeServiceAccountCredentials\u003c/code\u003e, demonstrated with sample code.\u003c/p\u003e\n"],["\u003cp\u003eExamples are provided for both \u003ccode\u003etpu_v1::TpuClient\u003c/code\u003e and \u003ccode\u003etpu_v2::TpuClient\u003c/code\u003e classes to illustrate the override process with service account snippets.\u003c/p\u003e\n"],["\u003cp\u003eThe documentation refers users to additional information, such as best practices for managing service account keys and a guide for authentication components.\u003c/p\u003e\n"]]],[],null,[]]
