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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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\u003eThe latest version available is 2.37.0-rc, with numerous previous versions from 2.36.0 down to 2.11.0 also available for reference.\u003c/p\u003e\n"],["\u003cp\u003eClient libraries typically use Application Default Credentials for authentication, but you can override this with UnifiedCredentialsOption.\u003c/p\u003e\n"],["\u003cp\u003eOverriding default credentials can be done by explicitly loading a service account key file, as demonstrated in the provided code example.\u003c/p\u003e\n"],["\u003cp\u003eSpecific examples are available for \u003ccode\u003epubsublite::AdminServiceClient\u003c/code\u003e and \u003ccode\u003epubsublite::TopicStatsServiceClient\u003c/code\u003e to demonstrate the authentication override.\u003c/p\u003e\n"],["\u003cp\u003eFor details and best practice for managing service account keys, you can refer to the linked guide and for factory function details for \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects you can refer to the linked Authentication Components page.\u003c/p\u003e\n"]]],[],null,[]]
