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::documentai_v1::DocumentProcessorServiceClient(
google::cloud::documentai_v1::MakeDocumentProcessorServiceConnection(
options));
}
[[["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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 a list of available versions for the Document AI C++ client library, ranging from version 2.11.0 to the latest release candidate 2.37.0-rc.\u003c/p\u003e\n"],["\u003cp\u003eThe default authentication method for the client libraries is Application Default Credentials, but you can override this by using the UnifiedCredentialsOption.\u003c/p\u003e\n"],["\u003cp\u003eThe provided example demonstrates how to explicitly load a service account key file to override the default credentials.\u003c/p\u003e\n"],["\u003cp\u003eFor further details on managing service account keys, refer to the "Best practices for managing service account keys" guide.\u003c/p\u003e\n"],["\u003cp\u003eYou can find additional information on creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects in the "Authentication Components" documentation.\u003c/p\u003e\n"]]],[],null,[]]
