fix production LDAP routing

config/initializers/omniauth.rb

@@ -25,3 +25,30 @@ end
 OmniAuth.config.on_failure = Proc.new { |env|
   OmniAuth::FailureEndpoint.new(env).redirect_to_failure
 }
+
+# Work around beacuse callback_url option causes
+# omniauth.auth to be nil in the authhash when
+# authenticating with LDAP.
+
+module OmniAuthLDAPExt
+    def request_phase
+      
+        rel_root = ENV['RELATIVE_URL_ROOT'].present? ? ENV['RELATIVE_URL_ROOT'] : '/b'
+        rel_root = '' if Rails.env == 'development'
+      
+        @callback_path = nil
+        path = options[:callback_path]
+        options[:callback_path] = "#{rel_root}/auth/ldap/callback"
+        form = super
+        options[:callback_path] = path
+        form
+    end
+end
+
+module OmniAuth
+    module Strategies
+        class LDAP
+            prepend OmniAuthLDAPExt
+        end
+    end
+end