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::shell_v1::CloudShellServiceClient(
google::cloud::shell_v1::MakeCloudShellServiceConnection(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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-07-02 UTC."],[[["This page provides documentation for overriding default authentication credentials when using Google Cloud client libraries."],["The most current version available is 2.37.0-rc, with a full list of previous versions ranging back to 2.11.0 also available."],["You can override the default Application Default Credentials (ADC) by using the `UnifiedCredentialsOption`, and the page demonstrates loading a service account key file as an example."],["Refer to the \"Best practices for managing service account keys\" guide for more details on managing these keys, as well as the \"Authentication Components\" section for more information on `google::cloud::Credentials` objects."]]],[]]
