config.ru

require "rack"
require "puma"

app = lambda { |env| [200, {'Content-Type' => 'text/plain'}, ['Hello World']] }

class ApiKeyValidator
  def initialize(app)
    @app = app
  end
  
  def call(env)
    request = Rack::Request.new(env)
    
    if request.has_header?('X-API-KEY') && request.get_header('X-API-KEY') == ENV['API-KEY']
      return @app.call(env)
    end
    
    [401, {'Content-Type' => 'text/plain'}, ['Unauthorized' ]]
  end
end

use ApiKeyValidator

map '/posts' do
  run lambda {|env| [200, { 'Content-Type' => 'text/plain'}, ['Post 1', 'Post 2', 'Post 3']]}
end

run app