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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 documents various versions of the C++ client library, specifically related to overriding authentication, with the latest version being 2.37.0-rc.\u003c/p\u003e\n"],["\u003cp\u003eThe library versions range from 2.11.0 up to the latest release candidate, 2.37.0-rc, and provide documentation on how to override default authentication credentials.\u003c/p\u003e\n"],["\u003cp\u003eOverriding default authentication is achieved by providing the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, allowing you to load a service account key file explicitly.\u003c/p\u003e\n"],["\u003cp\u003eExamples are available for \u003ccode\u003esupport_v2::CaseAttachmentServiceClient\u003c/code\u003e, \u003ccode\u003esupport_v2::CaseServiceClient\u003c/code\u003e, and \u003ccode\u003esupport_v2::CommentServiceClient\u003c/code\u003e, demonstrating how to use service account keys with different client classes.\u003c/p\u003e\n"],["\u003cp\u003eDefault authentication typically uses Application Default Credentials, and more information about authentication components, including factory functions for creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects, can be found in the Authentication Components section.\u003c/p\u003e\n"]]],[],null,[]]
