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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 provides documentation for overriding default authentication credentials when using Google Cloud client libraries, specifically for the Composer service.\u003c/p\u003e\n"],["\u003cp\u003eThe latest version documentation available is 2.37.0-rc, and this document includes documentation for versions from 2.11.0 up to 2.37.0-rc, including multiple minor version releases.\u003c/p\u003e\n"],["\u003cp\u003eOverriding authentication can be done by providing the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, exemplified by loading a service account key file via the \u003ccode\u003eMakeServiceAccountCredentials\u003c/code\u003e function.\u003c/p\u003e\n"],["\u003cp\u003eExamples for \u003ccode\u003eEnvironmentsClient\u003c/code\u003e and \u003ccode\u003eImageVersionsClient\u003c/code\u003e classes are provided to demonstrate overriding authentication in specific client contexts.\u003c/p\u003e\n"],["\u003cp\u003eThe documentation links to the "Best practices for managing service account keys" guide and the "Authentication Components" for further details on managing service account keys and creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects.\u003c/p\u003e\n"]]],[],null,[]]
