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::iot_v1::DeviceManagerClient(
google::cloud::iot_v1::MakeDeviceManagerConnection(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 2025-03-21 UTC."],[[["The client libraries default to using Application Default Credentials for authentication with Google Cloud Services, but this can be overridden when needed."],["Authentication credentials can be overridden by providing the `UnifiedCredentialsOption`, as demonstrated through loading a service account key file."],["The example given in the webpage showcases how to explicitly load a service account key file, which was chosen for its relative ease of comprehension."],["There are multiple versions of the documentation for reference, with `2.15.0-rc` being the latest version."],["The factory functions for creating `google::cloud::Credentials` objects are detailed in the Authentication Components section."]]],[]]
