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::networkconnectivity_v1::HubServiceClient(
google::cloud::networkconnectivity_v1::MakeHubServiceConnection(
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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 document lists available versions of the Network Connectivity C++ client library, ranging from version 2.11.0 up to the latest release candidate 2.37.0-rc.\u003c/p\u003e\n"],["\u003cp\u003eThe latest non-release candidate version available is 2.36.0, while the current version detailed in this specific page is 2.28.0.\u003c/p\u003e\n"],["\u003cp\u003eThe documentation outlines how to override the default authentication method using \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e and provides a code example that loads a service account key file for authentication.\u003c/p\u003e\n"],["\u003cp\u003eLinks are provided for examples with \u003ccode\u003eHubServiceClient\u003c/code\u003e and \u003ccode\u003ePolicyBasedRoutingServiceClient\u003c/code\u003e classes, demonstrating how to implement service account authentication.\u003c/p\u003e\n"],["\u003cp\u003eThe documentation refers users to external documentation to understand the best practices for managing service account keys.\u003c/p\u003e\n"]]],[],null,[]]
