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::gkeconnect_gateway_v1::GatewayControlClient(
google::cloud::gkeconnect_gateway_v1::MakeGatewayControlConnection(
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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 document provides information on how to override the default authentication credentials used by client libraries when interacting with Google Cloud Services.\u003c/p\u003e\n"],["\u003cp\u003eThe client libraries typically use Application Default Credentials for authentication, but this can be overridden by using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eAn example is provided showing how to load a service account key file for explicit authentication.\u003c/p\u003e\n"],["\u003cp\u003eThe document references a guide for best practices in managing service account keys and further information on \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe different versions of the documentation, ranging from version 2.29.0 to 2.37.0-rc, are listed for reference.\u003c/p\u003e\n"]]],[],null,[]]
