LINE Bot API Proxy

app.rb

require 'sinatra'
require 'httpclient'

CALLBACK_URI = URI.parse('http://example.com/callback')

configure do
  set :httpclient, HTTPClient.new
end

post '/callback' do
  settings.httpclient.post_async(
    CALLBACK_URI,
    request.body.read,
    {
      'Content-Type' => 'application/json; charset=UTF-8',
      'X-LINE-ChannelSignature' => request.env['X-LINE-ChannelSignature']
    })
  200
end