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 version-specific documentation for the C++ Vision API, ranging from version 2.11.0 up to the release candidate 2.37.0-rc."],["The primary focus of this page is to demonstrate how to override the default authentication credentials by supplying a service account key file using the `UnifiedCredentialsOption`."],["The document references examples using the `ImageAnnotatorClient` and `ProductSearchClient` classes within the Vision API to exemplify how to use a service account for authentication."],["The use of `Application Default Credentials` is discussed, which works for most applications but can be overridden when needed, as detailed in the example and related documentation."],["It also recommends reviewing the `Best practices for managing service account keys` for more details on managing keys and provides a link to `Authentication Components` to understand how to create credentials."]]],[]]
