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::resourcemanager_v3::FoldersClient(
google::cloud::resourcemanager_v3::MakeFoldersConnection(options));
}
Follow these links to find examples for other *Client classes:
[[["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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-07-09 UTC."],[[["The latest version of the resource manager is 2.37.0-rc, with version 2.27.0 also highlighted."],["The documentation provides a guide on how to override default authentication credentials for Google Cloud Services, which typically use Application Default Credentials."],["Overriding authentication can be achieved by providing a `UnifiedCredentialsOption`, as demonstrated by explicitly loading a service account key file."],["Examples are available for various `*Client` classes, including `FoldersClient`, `OrganizationsClient`, `ProjectsClient`, `TagBindingsClient`, `TagHoldsClient`, `TagKeysClient`, and `TagValuesClient`."],["Best practices for managing service account keys are linked, alongside a reference to authentication components for creating `google::cloud::Credentials` objects."]]],[]]
