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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 page provides documentation for overriding default authentication credentials in Google Cloud C++ client libraries for logging.\u003c/p\u003e\n"],["\u003cp\u003eThe latest release candidate version for C++ logging documentation is 2.37.0-rc, and multiple other versions are listed, ranging from 2.36.0 to 2.11.0.\u003c/p\u003e\n"],["\u003cp\u003eYou can override the default credentials by providing a \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, for example, by explicitly loading a service account key file using \u003ccode\u003eMakeServiceAccountCredentials\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eSpecific examples for overriding authentication are provided for \u003ccode\u003eConfigServiceV2Client\u003c/code\u003e, \u003ccode\u003eLoggingServiceV2Client\u003c/code\u003e, and \u003ccode\u003eMetricsServiceV2Client\u003c/code\u003e classes within the \u003ccode\u003elogging_v2\u003c/code\u003e namespace.\u003c/p\u003e\n"],["\u003cp\u003eFor detailed information on creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects and managing service account keys, consult the "Authentication Components" and the "Best practices for managing service account keys" guides.\u003c/p\u003e\n"]]],[],null,[]]
