The OmniAuth LTI gem provides a way for applications to authenticate users using LTI 1.1 specification.

It relies on ims-lti gem for validating LTI data.

Add the gem in your Gemfile:

gem 'omniauth-lti'

And install it using bundle

bundle install

Add the provider to your OmniAuth stack, giving the tool_consumer credentials:

Rails.application.config.middleware.use OmniAuth::Builder do
  provider :lti, :oauth_credentials => {:test => 'secret'}
end

Include Omniauth::Lti::Context in your application_controller:

class ApplicationController < ActionController::Base
  ...
  include Omniauth::Lti::Context
  ...
end

When you create the session in your sessions\_controller, call to save_lti_context for saving LTI context through all the application

For accessing the context anywhere in your application, just call the helper method lti_tool_provider. For instance, to show the title of the resource that call your application just put in your haml view:

=lti_tool_provider.resource_link_title

You can find an example web application in omniauth-lti-example-webapp

lti_tool_provider gives you the full IMS::LTI::ToolProvider class. Please refer to (https://github.com/instructure/ims-lti#returning-results-of-a-quizassignment) to see how to do outcomes with this class