About HttpForwarder

HttpForwarder is a gem that lets you easily forward a request from your app to a specified target. It also enables you to transform the request before doing so. For example, it is very handy when it comes to service communications in a microservices architecture.

Installation

Add this line to your application's Gemfile:

gem 'http_forwarder', github: 'leikir/http_forwarder'

And then execute:

$ bundle

Or install it yourself as:

$ gem install http_forwarder

Usage

Setup

Once you installed the gem, you have to include it in the controller you want to use it in:

  include HttpForwarder::Forwarder

Then you need to set up your routes in a new file config/initializers/forwarder.rb like this:

HttpForwarder::Forwarder.configure do |config|
  config.router.forward(:dogs).on(:create).to('http://doggy.woof')
  config.router.forward(:dogs).on(:index).to('http://doggos.woof')
  config.router.forward(:cats).to('http://kittykitty.miaw')
end

The argument of the method forward()is your controller name, the argument of the method on() is your method name and the argument of the method to() is the target you want to forward to. For example, in the example above, the method create of the dogs controller redirects the request to http://doggy.woof. It is mandatory to specify the controller and the target, whereas if you don't specify the action it will assume that all your controller methods redirect to the same url. In the example above, all the cats controller actions will redirect to http://kittykitty.miaw.

Headers whitelist

You can whitelist the headers you want to forward.

config.headers.allow(%w[Accept Content-Type])

Forwarding

Forwarding without modification

If you want to forward the request and render the response without any modification whatsoever, simply user the forward_and_render method:

def index
  forward_and_render
end

It will forward to your configured domain, with the same path as in input.

Examples:

• :get, http://my-dogs.mine/4 => :get, http://doggy.woof/4
• :post, http://my-cats.meow => :post, http://kittykitty.miaw

Modification is still possible, see below section.

Forwarding with response modification

If you want to manipulate the response, simply use the forward method, then manipulate the response object :

def update
  response = forward
  parsed_response = JSON.parse(response.body)
  parsed_response['data']['name'] = 'droopy'
  render json: parsed_response, status: response.status
end

Modifying the request before forwarding

Sometimes you might want to change the arriving request before forwarding it. To do so, you can pass a proc to our forward method to make the changes you want :

class DogsController < ApplicationController

  include HttpForwarder::Forwarder

  def create
    response_from_other_api = forward do |body, _path, _headers|
      body = JSON.parse(body)
      body['data']['name'] = 'rex'
      @body = body.to_json
    end
    render_response(response_from_other_api)
  end
end

In the example above we updated a json body to alter a key inside it. We didn't modify the path or headers so we could have went for:

  # modify only body
  forward do |body|
  ...
  # modify only path
  forward do |_body, path|
  ...
  # modify only body and headers
  forward do |body, _path, headers|
end

To effectively modify the variable inside the block you must assign value to the instance variable

  @body = body.to_json

  @body = ''

  @body = 'nil'

  @path = '/api/another/path'

  @headers = headers.select { |header| header == 'Content-Type'}

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/leikir/http_forwarder.