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::composer_v1::EnvironmentsClient(
google::cloud::composer_v1::MakeEnvironmentsConnection(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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 documents how to override the default authentication credentials for Google Cloud services, which typically use Application Default Credentials (ADC).\u003c/p\u003e\n"],["\u003cp\u003eUsers can override the default authentication by utilizing the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, as demonstrated with loading a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eThe examples provided showcase authentication credential overrides for \u003ccode\u003ecomposer_v1::EnvironmentsClient\u003c/code\u003e and \u003ccode\u003ecomposer_v1::ImageVersionsClient\u003c/code\u003e classes.\u003c/p\u003e\n"],["\u003cp\u003eThe content provides various documentation versions from 2.11.0 up to the latest version 2.37.0-rc, allowing access to documentation for specific releases.\u003c/p\u003e\n"],["\u003cp\u003eRefer to the "Best practices for managing service account keys" guide and "Authentication Components" for further information on service account key management and creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects.\u003c/p\u003e\n"]]],[],null,[]]
