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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 documentation for various versions of the Document AI C++ client library, ranging from version 2.11.0 to 2.37.0-rc, with 2.37.0-rc being the latest release candidate.\u003c/p\u003e\n"],["\u003cp\u003eThe client libraries generally use Application Default Credentials for authentication with Google Cloud Services, but this can be overridden if necessary.\u003c/p\u003e\n"],["\u003cp\u003eYou can override the default authentication by providing a \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, as demonstrated in the example code using a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eThe provided example demonstrates how to explicitly load a service account key file to override the authentication credentials for the Document AI service.\u003c/p\u003e\n"],["\u003cp\u003eFor comprehensive details on creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects, refer to the Authentication Components section of the documentation.\u003c/p\u003e\n"]]],[],null,[]]
