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));
}
[[["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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 various versions of the network connectivity service, ranging from version 2.11.0 up to the latest release candidate, 2.37.0-rc.\u003c/p\u003e\n"],["\u003cp\u003eThe content demonstrates how to override default authentication credentials using \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, especially for cases where Application Default Credentials are not suitable.\u003c/p\u003e\n"],["\u003cp\u003eAn example is provided that details the explicit loading of a service account key file to override default authentication in order to gain a deeper understanding of the code.\u003c/p\u003e\n"],["\u003cp\u003eThe page directs users to the "Best practices for managing service account keys" guide for more comprehensive details on service account management.\u003c/p\u003e\n"],["\u003cp\u003eFurther information on creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects can be found in the linked "Authentication Components" documentation.\u003c/p\u003e\n"]]],[],null,[]]
