Raise an error in production env if host_names is using production.localhost

config/initializers/verify_config.rb

@@ -0,0 +1,15 @@
+# Check that the app is configured correctly. Raise some helpful errors if something is wrong.
+
+if Rails.env.production? and ['localhost', 'production.localhost'].include?(Discourse.current_hostname)
+  puts <<END
+
+    Discourse.current_hostname = '#{Discourse.current_hostname}'
+
+    Please update the host_names property in config/database.yml
+    so that it uses the hostname of your site. Otherwise you will 
+    experience problems, like links in emails using #{Discourse.current_hostname}.
+
+END
+
+  raise "Invalid host_names in database.yml"
+end