Monday 20 May 2013

Better Script Delivery

I'm in the process of switching CDNs from Amazon's CloudFront to CloudFlare. While CloudFront has been generally good, it fell short in a couple of ways. So far, CloudFlare solves all of these problems and then gives the opportunity to have even more interesting possibilities.

There were two major problems with CloudFront:

  • No CNAME support. Not for HTTPS, at least. As a result, I've had to give you a script with a URL in it. But the problem is beyond just ugliness. It gives me no control to change CDNs in the future. I've been living with this so far, but it's far from ideal. CloudFlare solves this problem elegantly.
  • It's a dumb CDN. Like, really dumb. It doesn't do any content-negotiation for what I'd consider even the most basic things. For example, if you want your scripts to be gzipped, you'd have to upload pre-gizpped scripts to the CloudFront. If a browser comes along that doesn't understand gzip, it's out of luck.

The second issue might seem obvious and trivial, but has its consequences. For example, PageSpeed recommends that every asset on the page should have a Vary: Accept-Encoding header. However, on CloudFront if I provide a Vary header, I'd be lying to the network, because I'm not able to vary the content at all. As a result, all sites that had embedded Errorception's snippet would have seen a slight reduction in their PageSpeed score. Indeed, there have been requests to fix this.

Not only do the two problems above get fixed by the move to CloudFlare, it allows for very interesting possibilites in the future. Since CloudFlare is much more smart as compared to CloudFront, and since it effectively works as a caching-proxy, the possibilities are limitless! There are features I simply couldn't roll out on CloudFront which become trivial to do on CloudFlare.

Action needed

Unfortunately, this change requires you to change the script snippet that you've embedded on your site. I know it's a pain to have to do this. I apologize. The last time I asked you to do this was over a year and a half ago, so I assure you that these kinds of changes don't happen frequently. Please go to your Settings > Tracking snippet to get the new snippet.

Upgrade plan

The current script on Amazon's CloudFront will be supported for a couple of months more. Over this period, if there are any critical bugs, I'll be making releases to both the CloudFront and CloudFlare CDNs. Feature releases will not be rolled out to CloudFront, so you will not get any new features if you are using the old snippet. It's highly recommended that you upgrade as soon as possible to ensure that you have the very latest features.

1 comment:

  1. What are your thoughts if we rewrote the javascript as recommended in: