Incorrect image_id for provisioners/digital_ocean.yml in Chapter 8

[mattjmcnaughton]

First off, love the book! Have really enjoyed working my way through it.

One small note, I'm getting the error Failure talking to yum: Cannot retrieve repository metadata (repomd.xml) for repository: varnish-4.1. Please verify its path and try again" when trying to run provision.yml in the Chapter 8 Lamp Infrastructure Digital Ocean example. I believe the issue is that the digital ocean image_id in provisioners/digital_ocean.yml is 'centos-6-5-x32'. However, there is no x32 image for Varnish (based on my understanding of https://repo.varnish-cache.org/redhat/varnish-4.1/el6/). There is however an x64 image.

This error can be fixed by updating the image_id to centos-6-5-x64.

Thanks again for a fantastic book!

[geerlingguy]

I'm going to take a look at this during the weekend and hopefully get it updated. Thanks!