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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-07-09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."],[[["This page provides documentation for overriding default authentication credentials in Google Cloud C++ client libraries for the `resourcemanager` service."],["The most recent release candidate version is `2.37.0-rc`, and a list of previous versions from `2.36.0` down to `2.11.0` are available for reference and navigation."],["Authentication can be overridden by using the `UnifiedCredentialsOption`, demonstrated through loading a service account key file in the provided example code."],["Examples of overriding the default authentication credentials are provided for various `*Client` classes, such as `FoldersClient`, `OrganizationsClient`, `ProjectsClient`, `TagBindingsClient`, and others."],["The page highlights the use of Application Default Credentials as a default authentication mechanism and recommends the \"Best practices for managing service account keys\" guide for more details on service account key management."]]],[]]
