Class to help with generating OAuth2 tokens for app-to-app interactions

api.rake

namespace :api do
  task :create_client => :environment do
    raise "Requires name. id and secret are optional" unless ENV['name']
    
    @service ||= AuthServiceTools.new
    @service.create_client(ENV['name'], ENV['id'], ENV['secret'])

    puts @service.description
  end

  task :create_access_token => :environment do
    raise "Requires name. id and secret are optional" unless ENV['name']

    @service ||= AuthServiceTools.new
    @service.set_client_by_name(ENV['name']) unless @service.client
    @service.create_token

    puts @service.description
  end

  task :setup_access do
    raise "Requires name. id and secret are optional" unless ENV['name']

    @service ||= AuthServiceTools.new
    @service.create_client(ENV['name'], ENV['id'], ENV['secret'])
    @service.create_token

    puts @service.description
  end
end

auth_service_tools.rb

class AuthServiceTools
  attr_accessor :client, :token

  def create_client(name, id = nil, secret = nil)
    attrs = {name: name}
    attrs += {oauth_identifier: id, oauth_secret: secret} if id and secret
    @client = OAuth2::Provider.client_class.create!(attrs)
  end

  def set_client_by_name(name)
    @client = OAuth2::Provider.client_class.find_by_name!(name)
  end

  def create_token(resource_owner = nil, redirect_uri = '#')
    grant = client.authorizations.create!(resource_owner: resource_owner)
    code = grant.authorization_codes.create!(redirect_uri: redirect_uri)
    @token = client.authorization_codes.claim(code.code, code.redirect_uri)
  end

  def description
    output = []
    output << "Created OAuth client '#{client.name}'"
    output << "oauth_id:     #{client.oauth_identifier}"
    output << "oauth_secret: #{client.oauth_secret}"

    if token
      output << "access_token: #{token.access_token}"
      output << "refresh_token: #{token.refresh_token}"
    end

    output.join("\n")
  end
end

example_controller.rb

class ApiController < ApplicationController
  include OAuth2::Provider::Rails::ControllerAuthentication
  authenticate_with_oauth

  def index
    @allowed_posts = resource_owner.posts
  end

private
  def resource_owner
     request.env['oauth2'].resource_owner
  end
end