TCPSocket based implementation of ServerRenderingPool for react-on-rails, with safe error handling and auto-reconnect

README.md

This is an implementation of ServerRenderingPool for react-on-rails that connects to NodeJS process over a TCP socket, instead of a UNIX socket.

The code handles socket disconnections, and attempts to reestablish connection to NodeJS server process in these cases. Also, if a connection-related exception was caught, it will not raise an exception in Rails server, but report it to Airbrake and return empty result - to let standard front-end code deal run its course.

The should be placed into an initializer (e.g. config/initializers/react_on_rails.rb), and its configuration block expanded with your usual configuration.

react-on-rails.rb

module ReactOnRails
  class Configuration
    attr_accessor :server_addr, :server_port
  end

  module ServerRenderingPool
    class << self
      # Let configuration specify a server render method class itself,
      # instead of its symbolic name
      def pool
        ReactOnRails.configuration.server_render_method
      end
    end

    class NodeTCP < Node
      def self.server_render_js_with_console_logging(*args)
        super(*args)
      rescue SystemCallError, JSON::ParserError => e
        # If JS evaluation failed - reset the connection pool, expecting
        # a system call error or a malformed response only when
        # when there's a problem with NodeJS process connection
        reset_pool
        Airbrake.notify_or_ignore e
        { 'html' => '',
          'consoleReplayScript' => "<script>console.log('#{e}')</script>" }
      end

      class << self
        private

        # TCPSocket based js context connection
        def create_js_context
          cfg = ReactOnRails.configuration
          TCPSocket.new(cfg.server_addr, cfg.server_port).tap do |c|
            c.setsockopt(Socket::SOL_SOCKET, Socket::SO_KEEPALIVE, true)
          end
        end
      end
    end
  end
end

ReactOnRails.configure do |config|
  # NodeTCP pool parameters
  config.server_render_method = ReactOnRails::ServerRenderingPool::NodeTCP
  config.server_addr = '127.0.0.1'
  config.server_port = ENV['NODE_RENDER_PORT'].to_i
end