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::networkmanagement_v1::ReachabilityServiceClient(
google::cloud::networkmanagement_v1::MakeReachabilityServiceConnection(
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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 version of the documentation for network management is version 2.37.0-rc.\u003c/p\u003e\n"],["\u003cp\u003eThis page provides versioned documentation for the network management service, ranging from version 2.11.0 up to the latest release candidate, 2.37.0-rc.\u003c/p\u003e\n"],["\u003cp\u003eBy using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, you can override the default Application Default Credentials used to authenticate with Google Cloud Services.\u003c/p\u003e\n"],["\u003cp\u003eService account keys can be loaded explicitly, as demonstrated by the provided code example, for overriding default credentials.\u003c/p\u003e\n"],["\u003cp\u003eFor further details on creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects and managing service account keys, refer to the Authentication Components and Best practices for managing service account keys guide.\u003c/p\u003e\n"]]],[],null,[]]
