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 in Google Cloud C++ client libraries for various versions, starting from version 2.11.0 up to the latest release candidate 2.37.0-rc."],["The client libraries typically use Application Default Credentials (ADC), but users can override this by utilizing `UnifiedCredentialsOption` to specify alternative credentials."],["The example illustrates overriding with a service account key file, showing how to read the key file content and create a `ManagedIdentitiesServiceClient` with custom credentials."],["For more details and best practices on managing service account keys, users should refer to the provided documentation link."],["Further information on creating `google::cloud::Credentials` objects can be found in the \"Authentication Components\" section of the documentation."]]],[]]
