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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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\u003eThe latest release candidate version is 2.37.0-rc, and numerous other versions from 2.36.0 down to 2.11.0 are also available for the networkconnectivity override authentication.\u003c/p\u003e\n"],["\u003cp\u003eClient libraries typically use Application Default Credentials for authentication, but this can be overridden if required for a specific use case.\u003c/p\u003e\n"],["\u003cp\u003eTo override the default credentials, you can use the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e and, as demonstrated, explicitly load a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eThe provided code example demonstrates loading a service account key file, but refer to the "Best practices for managing service account keys" guide for more comprehensive information on managing such keys.\u003c/p\u003e\n"],["\u003cp\u003eThe "Authentication Components" documentation offers details on creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects.\u003c/p\u003e\n"]]],[],null,[]]
