simple rack middleware to set a csp header

csp_middleware.rb

module Rack
  # Simple rack middleware to
  # allow me to use a webworker locally
  class CspMiddleware
    def initialize(app, options = {})
      @app = app
      @options = options
    end

    def call(env)
      @doc = nil
      @request = Rack::Request.new(env)
      status, @headers, @body = @app.call(env)
      set_csp_headers
      [status, @headers, @body]
    end

    private

    def set_csp_headers
      @headers['Content-Security-Policy'] = "worker-src self"
    end
  end
end