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::logging_v2::ConfigServiceV2Client(
google::cloud::logging_v2::MakeConfigServiceV2Connection(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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 version-specific details and examples on how to override default authentication credentials when using Google Cloud client libraries.\u003c/p\u003e\n"],["\u003cp\u003eThe latest release candidate version available is 2.37.0-rc, and multiple prior versions are documented, ranging down to version 2.11.0.\u003c/p\u003e\n"],["\u003cp\u003eThe document demonstrates overriding authentication by providing a service account key file to the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e in the client library.\u003c/p\u003e\n"],["\u003cp\u003eThe examples illustrate overriding credentials for \u003ccode\u003elogging_v2::ConfigServiceV2Client\u003c/code\u003e, \u003ccode\u003elogging_v2::LoggingServiceV2Client\u003c/code\u003e, and \u003ccode\u003elogging_v2::MetricsServiceV2Client\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eIt recommends users to refer to the "Best practices for managing service account keys" guide and the "Authentication Components" for more in-depth details and best practices.\u003c/p\u003e\n"]]],[],null,[]]
