Remove unnecessary HTTP headers in my rails answers

Question

I am currently developing an API where size matters: I want the answer to contain as few bytes as possible. I optimized my JSON answer, but rails still responds with many strange headers

HTTP/1.1 200 OK
Server: nginx/0.7.67                            # Not from Rails, so ok.
Date: Wed, 25 Apr 2012 20:17:21 GMT             # Date does not matter. We use ETag Can I remove this?
ETag: "678ff0c6074b9456832a710a3cab8e22"        # Needed.
Content-Type: application/json; charset=utf-8   # Also needed.
Transfer-Encoding: chunked                      # The alternative would be Content-Length, so ok.
Connection: keep-alive                          # Good, less TCP overhead.
Status: 200 OK                                  # Redundant! How can I remove this?
X-UA-Compatible: IE=Edge,chrome=1               # Completely unneded.
Cache-Control: no-cache                         # Not needed.
X-Request-Id: c468ce87bb6969541c74f6ea761bce27  # Not a real header at all.
X-Runtime: 0.001376                             # Same goes for this
X-Rack-Cache: invalidate, pass                  # And this.

So there are lots of unnecessary HTTP headers. I could filter them in my server (nginx), but is there a way stop this directly in rails?

Answer 1

You can do this with a piece of Rack middleware. See https://gist.github.com/02c1cc8ce504033d61bf for an example of to do it in one.

When adding it to your app config, use something like config.middleware.insert_before(ActionDispatch::Static, ::HeaderDelete)

You want to insert it before whatever the first item in the list that displays when you run rake middleware, which in my case is ActionDispatch::Static.

http://guides.rubyonrails.org/rails_on_rack.html may be somewhat helpful if you haven't been exposed to Rack in the Rails context before.

Answer 2

Another option, since you're using Nginx, is the HttpHeadersMoreModule. This will allow you to have fine-grain control of exactly which headers are sent down the wire.

In your case, you'd specifically want to use the more_clear_headers directive, as such:

more_clear_headers Server Date Status X-UA-Compatible Cache-Control X-Request-Id X-Runtime X-Rack-Cache;

This also clears the Server header, since it's not really necessary, and if you're trying to save bytes, every little bit helps.

This module does require you to compile Nginx on your own, but that really shouldn't scare you. Nginx is very easy to compile, just follow the installation instructions.