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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-07-26 UTC."],[[["This page provides documentation for overriding default authentication credentials in Google Cloud C++ client libraries for the Resource Manager, starting from version 2.11.0 to the latest version 2.37.0-rc."],["Client libraries typically use Application Default Credentials (ADC) for authentication, but users can override this behavior using the `UnifiedCredentialsOption`."],["The provided example shows how to override the default credentials by loading a service account key file."],["Links are provided to examples for `FoldersClient`, `OrganizationsClient`, `ProjectsClient`, `TagBindingsClient`, `TagHoldsClient`, `TagKeysClient`, and `TagValuesClient` classes."],["For more details on the management of service accounts consult the \"Best practices for managing service account keys\" guide."]]],[]]
