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::domains_v1::DomainsClient(
google::cloud::domains_v1::MakeDomainsConnection(options));
}
[[["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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-07-26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 details how to override default authentication credentials for Google Cloud Services, which typically rely on Application Default Credentials."],["You can override the default credentials by using the `UnifiedCredentialsOption`, as demonstrated in the example with the service account key file."],["The provided example demonstrates overriding authentication by loading a service account key file using the `MakeServiceAccountCredentials` function within the `UnifiedCredentialsOption`."],["The page also lists available versions of the content, from version 2.12.0 up to the latest release candidate 2.37.0-rc."],["Consult the 'Best practices for managing service account keys' guide for more details on how to manage your service account keys securely, as this example provides the basics."]]],[]]
