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::domains_v1::DomainsClient(
google::cloud::domains_v1::MakeDomainsConnection(options));
}
[[["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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 various versions of the C++ client library, ranging from version 2.12.0 to the latest release candidate 2.37.0-rc, for managing authentication in Google Cloud services.\u003c/p\u003e\n"],["\u003cp\u003eThe client libraries typically utilize Application Default Credentials for authentication, but users can override these defaults when required.\u003c/p\u003e\n"],["\u003cp\u003eThe process to override default authentication utilizes the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, and a detailed example demonstrates explicitly loading credentials from a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eUsers are advised to refer to the provided guide on managing service account keys for best practices when overriding default authentication methods.\u003c/p\u003e\n"],["\u003cp\u003eFurther information on creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects can be found in the linked "Authentication Components" section.\u003c/p\u003e\n"]]],[],null,[]]
