Old Ruby 1.9.1 Descartes connects with Graphite, new 1.9.3 Descartes does not

[davecowen]

I had previously set up Descartes around a year ago, and it's been working well for us. It was originally set up with Ruby 1.9.1.

I made several attempts to upgrade it to a clone of the latest git repo and an upgrade to Ruby 1.9.3, but could never get it working - Descartes would launch, but would never pull graphs from graphite. I then moved ahead and set up a Ruby 1.9.3 instance from scratch, configured the new env file, and it's the same behavior.

There is no difference in foreman output. The crux of the issue is that while both the old and new Descartes servers load "/metrics/?_=token HTTP/1.1", with the old server the browser begins loading:

render?target=graphitename&from=-1h&format=json&_=token

but the new server never makes the connection. I don't see any obvious errors in the logs - it's like the new 1.9.3 Descartes instance never reaches out to graphite whatsoever.