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 page details how to override the default Application Default Credentials (ADC) for authenticating with Google Cloud Services, which is done by providing a `UnifiedCredentialsOption`."],["The content provides a code example demonstrating how to explicitly load a service account key file using `google::cloud::UnifiedCredentialsOption` and `MakeServiceAccountCredentials`."],["Links are provided to specific examples for different `*Client` classes, including `iam_admin_v1::IAMClient`, `iam_credentials_v1::IAMCredentialsClient`, `iam_v1::IAMPolicyClient`, and `iam_v2::PoliciesClient`."],["The page includes a reference to best practices for managing service account keys, as well as a link to more information on authentication components."],["This page lists the different version releases of the CPP documentation, with the latest release being 2.37.0-rc, all the way back to 2.11.0, and links for each to documentation about overriding authentication."]]],[]]