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::vision_v1::ImageAnnotatorClient(
google::cloud::vision_v1::MakeImageAnnotatorConnection(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"]],[["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 2025-03-14 UTC."],[[["This document provides guidance on overriding default authentication credentials when interacting with Google Cloud Services using C++ client libraries."],["The latest version of the C++ library is 2.37.0-rc, and a comprehensive list of prior versions, down to 2.11.0, is available for reference."],["The `UnifiedCredentialsOption` allows developers to override Application Default Credentials, and an example is provided demonstrating how to load a service account key file."],["Examples for other client classes like `vision_v1::ImageAnnotatorClient` and `vision_v1::ProductSearchClient` are linked for further exploration."],["The document links to additional resources on managing service account keys and the authentication components for creating `google::cloud::Credentials` objects."]]],[]]