class ForwardHost

def rewrite_env(env)
  env["HTTP_HOST"] = "example.com"
  env
end

def rewrite_response(triplet)
  status, headers, body = triplet
  # example of inserting an additional header
  headers["X-Foo"] = "Bar"
  
  # if you rewrite env, it appears that content-length isn't calculated correctly
  # resulting in only partial responses being sent to users
  # you can remove it or recalculate it here
  headers["content-length"] = nil
  triplet
end