This is a fork of Microsoft's official ruby gem for Azure Active Directory as an omniauth provider, now made availbale as its own repository and ruby gem. Most of this README is taken from Microsoft's original gem, found here, with additions to make it compatible with other providers.

OmniAuth strategy to authenticate to Azure Active Directory via OpenId Connect.

Before starting, set up a tenant and register a Web Application at https://manage.windowsazure.com. Note your client id and tenant for later.

While Microsoft's original gem still works, when Azure AD is being used as the only provider for omniauth, it hasn't been updated in a significant amount of time. When trying to implement this gem in my own projects, I faced the issue of having many runtime dependency conflicts, meaning I either needed to use older versions of other provider gems (not always possible), or update this gem for myself. This repo is the result of deciding on the latter.

Find Microsoft's examples here to help you get started with learning the Azure Identity system. This includes tutorials for native clients such as Windows, Windows Phone, iOS, OSX, Android, and Linux. There you can also find full walkthroughs for authentication flows such as OAuth2, OpenID Connect, Graph API, and other features provided by Microsoft.

Add to your Gemfile:

gem 'omniauth-activedirectory'

If you are already using OmniAuth, adding AzureAD is as simple as adding a new provider to your OmniAuth::Builder. The provider requires your AzureAD client id and your AzureAD tenant.

For example, in Rails you would add this in config/initializers/omniauth.rb:

Rails.application.config.middleware.use OmniAuth::Builder do
  provider :activedirectory, ENV['AAD_CLIENT_ID'], ENV['AAD_TENANT']
  # other providers here
end

When you want to authenticate the user, simply redirect them to /auth/activedirectory. From there, OmniAuth will takeover. Once the user authenticates (or fails to authenticate), they will be redirected to /auth/activedirectory/callback. The authentication result is available in request.env['omniauth.auth'].

Rails' built-in CSRF protection can cause some hassles with omniauth, since a POST request is being made to your application by the provider, without an anti forgery token from you application. We need to tells Rails not to perform this check on the specific action being used for authentication with omniauth. Typically, your callback will be routed to the #create action in the Sessions controller. If this is the case for your app, app the following line in the beggining of the sessions controller:

skip_before_action :verify_authenticity_token, only: :create

Make sure that nothing sensitive is happening in this action that could expose your app to CSRF attacks. It should pretty much just get the data in the POST request and use it to create a new session.

OmniAuth AzureAD tries to be consistent with the auth hash schema recommended by OmniAuth. https://github.com/intridea/omniauth/wiki/Auth-Hash-Schema.

Here's an example of an authentication hash available in the callback. You can access this hash as request.env['omniauth.auth'].

  :provider => "azureactivedirectory",
  :uid => "123456abcdef",
  :info => {
    :name => "John Smith",
    :email => "jsmith@contoso.net",
    :first_name => "John",
    :last_name => "Smith"
  },
  :credentials => {
    :code => "ffdsjap9fdjw893-rt2wj8r9r32jnkdsflaofdsa9"
  },
  :extra => {
    :session_state => '532fgdsgtfera32',
    :raw_info => {
      :id_token => "fjeri9wqrfe98r23.fdsaf121435rt.f42qfdsaf",
      :id_token_claims => {
        "aud" => "fdsafdsa-fdsafd-fdsa-sfdasfds",
        "iss" => "https://sts.windows.net/fdsafdsa-fdsafdsa/",
        "iat" => 53315113,
        "nbf" => 53143215,
        "exp" => 53425123,
        "ver" => "1.0",
        "tid" => "5ffdsa2f-dsafds-sda-sds",
        "oid" => "fdsafdsaafdsa",
        "upn" => "jsmith@contoso.com",
        "sub" => "123456abcdef",
        "nonce" => "fdsaf342rfdsafdsafsads"
      },
      :id_token_header => {
        "typ" => "JWT",
        "alg" => "RS256",
        "x5t" => "fdsafdsafdsafdsa4t4er32",
        "kid" => "tjiofpjd8ap9fgdsa44"
      }
    }
  }