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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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\u003eThis document provides information on how to override the default authentication credentials used by client libraries when interacting with Google Cloud Services.\u003c/p\u003e\n"],["\u003cp\u003eThe latest version available is \u003ccode\u003e2.37.0-rc\u003c/code\u003e, with a list of other versions ranging from \u003ccode\u003e2.36.0\u003c/code\u003e down to \u003ccode\u003e2.11.0\u003c/code\u003e, each linking to their respective documentation.\u003c/p\u003e\n"],["\u003cp\u003eUsers can override default credentials by providing the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, and an example is demonstrated using a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eExamples of overriding authentication for \u003ccode\u003etpu_v1::TpuClient\u003c/code\u003e and \u003ccode\u003etpu_v2::TpuClient\u003c/code\u003e classes are available via provided links.\u003c/p\u003e\n"],["\u003cp\u003eThe document references the \u003ccode\u003eBest practices for managing service account keys\u003c/code\u003e guide and the \u003ccode\u003eAuthentication Components\u003c/code\u003e for further information.\u003c/p\u003e\n"]]],[],null,[]]
