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::managedidentities_v1::ManagedIdentitiesServiceClient(
google::cloud::managedidentities_v1::
MakeManagedIdentitiesServiceConnection(options));
}
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-03-14 UTC."],[[["This page provides documentation for overriding default authentication credentials when using Google Cloud C++ client libraries for Managed Identities."],["The latest release is version 2.37.0-rc, and the page contains links to previous versions, starting from 2.36.0 down to 2.11.0 of this library."],["Client libraries typically use Application Default Credentials (ADC), but users can override this by providing the `UnifiedCredentialsOption`, such as loading a service account key file."],["The example demonstrates how to load service account credentials from a key file using `MakeServiceAccountCredentials`, but users are encouraged to refer to the best practices guide for managing service account keys."],["The Authentication Components section is referenced for more information on creating `google::cloud::Credentials` objects using factory functions."]]],[]]