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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 page details how to override the default authentication credentials used by the client libraries when interacting with Google Cloud Services, specifically within the context of the provided C++ library versions.\u003c/p\u003e\n"],["\u003cp\u003eThe latest version of the C++ library for Pub/Sub Lite is 2.37.0-rc, with a range of previous versions from 2.36.0 down to 2.11.0 also listed, alongside their corresponding documentation links.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e can be used to override the default \u003ca href=\"https://cloud.google.com/docs/authentication#adc\"\u003eApplication Default Credentials\u003c/a\u003e, as demonstrated in the example code that loads a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eExamples on overriding credentials can also be found for \u003ccode\u003epubsublite::AdminServiceClient\u003c/code\u003e and \u003ccode\u003epubsublite::TopicStatsServiceClient\u003c/code\u003e classes, with links to relevant documentation for version 2.33.0 provided.\u003c/p\u003e\n"],["\u003cp\u003eRefer to the documentation on \u003ca href=\"https://cloud.google.com/cpp/docs/reference/common/latest/group__guac.html\"\u003eAuthentication Components\u003c/a\u003e and the \u003ca href=\"https://cloud.google.com/iam/docs/best-practices-for-managing-service-account-keys\"\u003eBest practices for managing service account keys\u003c/a\u003e guide for more information.\u003c/p\u003e\n"]]],[],null,[]]
