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 provides version-specific references for overriding default authentication credentials in C++ client libraries when interacting with Google Cloud Services."],["The latest release candidate is version 2.37.0-rc, with the document listing versions from 2.37.0-rc down to 2.11.0."],["Overriding authentication can be accomplished by providing the `UnifiedCredentialsOption`, as demonstrated in the provided C++ code example which shows loading a service account key file."],["Examples for overriding credentials are provided for `iam_admin_v1::IAMClient`, `iam_credentials_v1::IAMCredentialsClient`, `iam_v1::IAMPolicyClient`, and `iam_v2::PoliciesClient` classes."],["Users are advised to consult the \"Best practices for managing service account keys\" guide for more information on service account key management."]]],[]]