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::support_v2::CaseAttachmentServiceClient(
google::cloud::support_v2::MakeCaseAttachmentServiceConnection(
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"]],[["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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 details how to override default authentication credentials using \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e in Google Cloud C++ client libraries, specifically in the context of versions 2.12.0 through 2.37.0-rc.\u003c/p\u003e\n"],["\u003cp\u003eThe latest version available is 2.37.0-rc, with multiple prior releases listed, all the way back to version 2.12.0.\u003c/p\u003e\n"],["\u003cp\u003eThe example demonstrates loading a service account key file to override the default Application Default Credentials for authentication with Google Cloud Services.\u003c/p\u003e\n"],["\u003cp\u003eLinks to examples for other \u003ccode\u003e*Client\u003c/code\u003e classes like \u003ccode\u003eCaseAttachmentServiceClient\u003c/code\u003e, \u003ccode\u003eCaseServiceClient\u003c/code\u003e, and \u003ccode\u003eCommentServiceClient\u003c/code\u003e are provided for reference.\u003c/p\u003e\n"],["\u003cp\u003eIt's crucial to review the "Best practices for managing service account keys" guide to ensure secure credential management.\u003c/p\u003e\n"]]],[],null,[]]
