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::config_v1::ConfigClient(
google::cloud::config_v1::MakeConfigConnection(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."],[[["This page details how to override the default authentication credentials used by client libraries when interacting with Google Cloud Services."],["The default authentication uses Application Default Credentials, but you can override this by using the `UnifiedCredentialsOption`."],["A service account key file can be explicitly loaded to override default credentials, as demonstrated in the provided example."],["The latest version of documentation provided on this webpage is 2.37.0-rc, but many prior versions of documentation are available such as 2.36.0 all the way back to 2.16.0."],["For more information on the factory functions to create `google::cloud::Credentials` objects, you can refer to the \"Authentication Components\" page."]]],[]]
