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::apikeys_v2::ApiKeysClient(
google::cloud::apikeys_v2::MakeApiKeysConnection(options));
}
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14 UTC."],[[["\u003cp\u003eThe latest version available is 2.37.0-rc, with several other previous versions listed, ranging down to version 2.11.0.\u003c/p\u003e\n"],["\u003cp\u003eClient libraries use Application Default Credentials for authentication, but this can be overridden as needed.\u003c/p\u003e\n"],["\u003cp\u003eYou can override default authentication by utilizing \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e and explicitly loading a service account key file, as demonstrated in the provided example.\u003c/p\u003e\n"],["\u003cp\u003eThe example shown provides a simple way to load credentials, but the \u003ca href=\"https://cloud.google.com/iam/docs/best-practices-for-managing-service-account-keys\"\u003eBest practices for managing service account keys\u003c/a\u003e guide should be consulted for more complex implementations.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ca href=\"https://cloud.google.com/cpp/docs/reference/common/latest/group__guac.html\"\u003eAuthentication Components\u003c/a\u003e link gives further information on creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects.\u003c/p\u003e\n"]]],[],null,[]]
