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::channel_v1::CloudChannelServiceClient(
google::cloud::channel_v1::MakeCloudChannelServiceConnection(options));
}
[[["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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 webpage provides documentation for overriding default authentication credentials when using Google Cloud client libraries, specifically focusing on the \u003ccode\u003echannel-override-authentication\u003c/code\u003e within the C++ context.\u003c/p\u003e\n"],["\u003cp\u003eThe most recent version available is \u003ccode\u003e2.37.0-rc\u003c/code\u003e, with a historical list of versions extending down to \u003ccode\u003e2.11.0\u003c/code\u003e for the C++ documentation.\u003c/p\u003e\n"],["\u003cp\u003eUsers can override the default \u003ca href=\"https://cloud.google.com/docs/authentication#adc\"\u003eApplication Default Credentials\u003c/a\u003e by utilizing the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe documentation provides an example demonstrating how to load a service account key file and create a client with the overridden credentials.\u003c/p\u003e\n"],["\u003cp\u003eThe webpage also links to further information, including the \u003ccode\u003eBest practices for managing service account keys\u003c/code\u003e guide and the Authentication Components documentation.\u003c/p\u003e\n"]]],[],null,[]]
