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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 in the client libraries, which typically use Application Default Credentials (ADC).\u003c/p\u003e\n"],["\u003cp\u003eThe most recent version available for reference is \u003ccode\u003e2.37.0-rc\u003c/code\u003e, but many previous versions from \u003ccode\u003e2.36.0\u003c/code\u003e to \u003ccode\u003e2.11.0\u003c/code\u003e are documented as well.\u003c/p\u003e\n"],["\u003cp\u003eYou can override the default by providing a \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, specifically demonstrated with loading a service account key file, using \u003ccode\u003egoogle::cloud::MakeServiceAccountCredentials\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eExamples are provided for \u003ccode\u003esupport_v2::CaseAttachmentServiceClient\u003c/code\u003e, \u003ccode\u003esupport_v2::CaseServiceClient\u003c/code\u003e, and \u003ccode\u003esupport_v2::CommentServiceClient\u003c/code\u003e to show implementation.\u003c/p\u003e\n"],["\u003cp\u003eIt is recommended to reference the 'Best practices for managing service account keys' and 'Authentication Components' for more information on managing credentials.\u003c/p\u003e\n"]]],[],null,[]]
