README.md

OAuth2 Access Token Generation Library

This library contains helpers to create OAuth2 access tokens. This may be useful when trying to access customer services deployed to Cloud Run, or when using Google APIs that lack a client library in google-cloud-cpp.

While this library is GA, please note that the Google Cloud C++ client libraries do not follow Semantic Versioning.

Quickstart

The quickstart/ directory contains a minimal environment to get started using this client library in a larger project. The following "Hello World" program is used in this quickstart, and should give you a taste of this library.

For detailed instructions on how to build and install this library, see the top-level README.

#include "google/cloud/oauth2/access_token_generator.h"
#include <iostream>

int main(int argc, char* argv[]) try {
  if (argc != 1) {
    std::cerr << "Usage: " << argv[0] << "\n";
    return 1;
  }

  // Use Application Default Credentials to initialize an AccessTokenGenerator
  // retrieve the access token.
  auto credentials = google::cloud::MakeGoogleDefaultCredentials();
  auto generator =
      google::cloud::oauth2::MakeAccessTokenGenerator(*credentials);
  auto token = generator->GetToken();
  if (!token) throw std::move(token).status();
  // Only print the first few characters to avoid leaking tokens in test logs.
  std::cout << "The access token starts with " << token->token.substr(0, 16)
            << "\n";

  return 0;
} catch (google::cloud::Status const& status) {
  std::cerr << "google::cloud::Status thrown: " << status << "\n";
  return 1;
}

More Information

• Using OAuth 2.0 to Access Google APIs: for general information around OAuth2 and their use in Google APIs.
• Reference doxygen documentation for each release of this client library
• Detailed header comments in our public .h files