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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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.\u003c/p\u003e\n"],["\u003cp\u003eThe latest release candidate is version 2.37.0-rc, and the documentation covers a range of versions from 2.11.0 up to 2.37.0-rc for logging.\u003c/p\u003e\n"],["\u003cp\u003eThe client libraries typically use Application Default Credentials (ADC), but the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e can be used to explicitly set authentication, such as with a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eExamples are provided for how to override credentials with service account keys 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\u003eThe documentation links to further information on authentication components and best practices for managing service account keys.\u003c/p\u003e\n"]]],[],null,[]]
