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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 other versions from 2.36.0 down to 2.11.0 also being accessible.\u003c/p\u003e\n"],["\u003cp\u003eBy default, client libraries authenticate using Application Default Credentials, but this can be overridden for specific use cases.\u003c/p\u003e\n"],["\u003cp\u003eYou can override the default authentication by using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, such as explicitly loading a service account key file as provided in the examples.\u003c/p\u003e\n"],["\u003cp\u003eExamples of overriding authentication credentials are provided for \u003ccode\u003epubsublite::AdminServiceClient\u003c/code\u003e and \u003ccode\u003epubsublite::TopicStatsServiceClient\u003c/code\u003e classes.\u003c/p\u003e\n"],["\u003cp\u003eThe document recommends checking the "Best practices for managing service account keys" guide and also provides a link for "Authentication Components" for more details on authentication.\u003c/p\u003e\n"]]],[],null,[]]
