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::iam_admin_v1::IAMClient(
google::cloud::iam_admin_v1::MakeIAMConnection(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 details how to override the default Application Default Credentials (ADC) used by Google Cloud client libraries for authentication."],["The `UnifiedCredentialsOption` can be used to override default credentials, as demonstrated in the example using a service account key file."],["The latest release of the documentation is version 2.37.0-rc, while the current document focuses on version 2.21.0."],["Examples for overriding authentication credentials can be found for several client classes, including `iam_admin_v1::IAMClient`, `iam_credentials_v1::IAMCredentialsClient`, `iam_v1::IAMPolicyClient`, and `iam_v2::PoliciesClient`."],["The documentation provides a link to best practices for managing service account keys and another for further information on authentication components."]]],[]]
