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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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\u003eThe webpage provides documentation for various versions of the Document AI C++ client library, ranging from version 2.11.0 to 2.37.0-rc, with links to each version's documentation.\u003c/p\u003e\n"],["\u003cp\u003eThe latest release candidate version of the Document AI C++ client library is 2.37.0-rc.\u003c/p\u003e\n"],["\u003cp\u003eThe client libraries primarily utilize Application Default Credentials for authentication with Google Cloud Services, but offer methods to override these defaults.\u003c/p\u003e\n"],["\u003cp\u003eOverriding default credentials can be achieved using \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, such as by explicitly loading a service account key file, as demonstrated in the example code.\u003c/p\u003e\n"],["\u003cp\u003eUsers can find additional information on authentication components and managing service account keys by following the provided links to Authentication Components and the Best practices for managing service account keys.\u003c/p\u003e\n"]]],[],null,[]]
