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::functions_v1::CloudFunctionsServiceClient(
google::cloud::functions_v1::MakeCloudFunctionsServiceConnection(
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 versioned documentation for overriding authentication credentials in Google Cloud C++ client libraries, with the latest version being 2.37.0-rc."],["The libraries typically use Application Default Credentials, but this can be overridden by using the `UnifiedCredentialsOption`."],["A service account key file can be loaded to override the default credentials, as demonstrated in the example provided using `MakeServiceAccountCredentials`."],["Examples for overriding credentials in other `*Client` classes, such as `functions_v1::CloudFunctionsServiceClient` and `functions_v2::FunctionServiceClient`, are available via provided links."],["Refer to the \"Best practices for managing service account keys\" guide and \"Authentication Components\" for more detailed information on managing credentials and creating `google::cloud::Credentials` objects."]]],[]]
