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::pubsublite::AdminServiceClient(
google::cloud::pubsublite::MakeAdminServiceConnection(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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 document details how to override the default Application Default Credentials (ADC) for authenticating with Google Cloud Services, using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe latest available version is \u003ccode\u003e2.37.0-rc\u003c/code\u003e, with numerous prior versions listed, including the currently viewed \u003ccode\u003e2.26.0\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eA service account key file can be explicitly loaded to override default authentication, as demonstrated in the provided code example using \u003ccode\u003eMakeServiceAccountCredentials\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eExamples of overriding authentication are available for the \u003ccode\u003epubsublite::AdminServiceClient\u003c/code\u003e and \u003ccode\u003epubsublite::TopicStatsServiceClient\u003c/code\u003e classes.\u003c/p\u003e\n"],["\u003cp\u003eThe document references a guide on best practices for managing service account keys and provides a link for further information on authentication components.\u003c/p\u003e\n"]]],[],null,[]]
