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::storagecontrol_v2::StorageControlClient(
google::cloud::storagecontrol_v2::MakeStorageControlConnection(
options));
}
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14 UTC."],[[["\u003cp\u003eThis page provides version-specific documentation for overriding authentication in the C++ Storage Control client library, with links to versions ranging from 2.21.0 to the latest release candidate, 2.37.0-rc.\u003c/p\u003e\n"],["\u003cp\u003eThe client libraries typically use Application Default Credentials for authentication, but this can be overridden when needed.\u003c/p\u003e\n"],["\u003cp\u003eAuthentication can be overridden by providing a UnifiedCredentialsOption, such as loading a service account key file explicitly.\u003c/p\u003e\n"],["\u003cp\u003eThe example provided details how to use the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e by loading a service account key file, which can be adapted for other \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e use cases.\u003c/p\u003e\n"],["\u003cp\u003eBest practices for managing service account keys and additional details on creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects are available through external links provided.\u003c/p\u003e\n"]]],[],null,[]]
