rest-client not caching responses from Heroku

Question

we are running our Ruby on Rails (4.0) application (call it: 'carwow') on Heroku, url is http://www.carwow.co.uk on our controller response we are setting http caching expire with:

expires_in XXX.seconds, :public => true

Now, let's try running on a ruby console the following code: (you need to run gem install rest-client-components first):

require 'restclient/components'
require 'rack/cache'

RestClient.enable Rack::Cache, :metastore => 'file:/tmp/cache/meta', :entitystore => 'file:/tmp/cache/body'

RestClient.get('http://www.carwow.co.uk'); nil
RestClient.get('http://www.carwow.co.uk'); nil

RestClient.get('https://api.github.com/users/octocat/orgs') ; nil
RestClient.get('https://api.github.com/users/octocat/orgs') ; nil

The second request to 'carwow' will not used any cached version and it will display the following: cache: [GET ] miss, store

The second request to github will display cache: [GET ] fresh

When we run the 'carwow' application locally both in dev and production mode (unicorn server like on Heroku) the second request displays cache: [GET ] fresh

We started believing that there might be something wrong in the way we set HTTP headers but we can't pinpoint the problem. Has anyone ever experienced this?

Kind regards

Answer 1

We fixed it using this option when configuring the client's rack cache:

ignore_headers: ['X-Content-Digest']

More details on the reasons why this fixes it can be found on this post: https://github.com/rtomayko/rack-cache/issues/59