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::storagetransfer_v1::StorageTransferServiceClient(
google::cloud::storagetransfer_v1::MakeStorageTransferServiceConnection(
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 2025-04-02 UTC."],[[["The latest version available is 2.37.0-rc, with numerous other versions, starting at 2.11.0, also listed for reference."],["By default, the client libraries employ Application Default Credentials for authentication with Google Cloud Services."],["You can override the default authentication by using the UnifiedCredentialsOption, which allows for the explicit loading of credentials like a service account key file."],["The provided code example demonstrates how to override authentication by loading a service account key file, using the `google::cloud::UnifiedCredentialsOption`."],["For comprehensive details on creating `google::cloud::Credentials` objects, refer to the \"Authentication Components\" section, and consult the service key best practices for further information."]]],[]]