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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 services, covering versions from 2.11.0 to 2.37.0-rc.\u003c/p\u003e\n"],["\u003cp\u003eThe latest release candidate for logging service authentication override is version 2.37.0-rc.\u003c/p\u003e\n"],["\u003cp\u003eBy default, Google Cloud C++ client libraries use Application Default Credentials (ADC), but this can be overridden by providing a \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, such as loading a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eExamples of overriding credentials for specific logging client classes like \u003ccode\u003eConfigServiceV2Client\u003c/code\u003e, \u003ccode\u003eLoggingServiceV2Client\u003c/code\u003e, and \u003ccode\u003eMetricsServiceV2Client\u003c/code\u003e are available.\u003c/p\u003e\n"],["\u003cp\u003eFor best practices for service account key management, and more information on authentication components you can refer to the linked external resources.\u003c/p\u003e\n"]]],[],null,[]]
