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::run_v2::ExecutionsClient(
google::cloud::run_v2::MakeExecutionsConnection(options));
}
Follow these links to find examples for other *Client classes:
[[["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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-07-02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 document provides a version history, from 2.11.0 to 2.37.0-rc, for overriding authentication in Google Cloud C++ client libraries."],["The latest version for overriding authentication is 2.37.0-rc, as per the provided documentation."],["Client libraries use Application Default Credentials for authentication, but users can override this using `UnifiedCredentialsOption`."],["Overriding authentication can be achieved by explicitly loading a service account key file, as demonstrated in the provided example."],["There are examples provided for multiple `*Client` classes, including `run_v2::ExecutionsClient`, `run_v2::JobsClient`, `run_v2::RevisionsClient`, `run_v2::ServicesClient`, and `run_v2::TasksClient`."]]],[]]