Support multiple trusted proxy ip addresses (#3639)

* Support multiple trusted proxy ip addresses

* correct coding style

config/environments/production.rb

@@ -38,7 +38,7 @@ Rails.application.configure do
   config.action_dispatch.x_sendfile_header = 'X-Accel-Redirect' # for NGINX
 
   # Allow to specify public IP of reverse proxy if it's needed
-  config.action_dispatch.trusted_proxies = [IPAddr.new(ENV['TRUSTED_PROXY_IP'])] unless ENV['TRUSTED_PROXY_IP'].blank?
+  config.action_dispatch.trusted_proxies = ENV['TRUSTED_PROXY_IP'].split.map { |item| IPAddr.new(item) } unless ENV['TRUSTED_PROXY_IP'].blank?
 
   # Use the lowest log level to ensure availability of diagnostic information
   # when problems arise.