Socks and Sandals

A couple hours ago I moved this blog, my main website and the PhillyLambda homepage over to the Slicehost service. I’ve been a Dreamhost customer since 2002 and back then they were great and cheap. They were great for a while after that, and then they were OK but now they are pretty bad. Routinely, when I SSH into Dreamhost, I see load averages in the double digits (one time it was 135+). Every time I post to this blog, I have to hit Publish and then hit back about 5 times to get it to really commit because the FastCGI keeps snapping between Apache and Rails and throwing up a 500 error. I was getting pretty tired of it all.

So, for just a little bit more money I get my own dedicated VPS where I can run whatever I want. I’d heard really good things about Slicehost for a while so I decided that when I got the time, I’d move my sites over there. I also am using DNS services from Nettica as they were very good to me while I was at Commerce360. Here’s hoping that when I press Publish this time it just does it! ;)

When I started using Amazon’s EC2 service I realized pretty quickly that the traditional load-balancing solution of putting a big, honkin’ F5 BIG-IP in front of the servers wasn’t going to work out. Amazon doesn’t currently rent F5’s ;)

So, I went looking around for a DNS-based load-balancing solution that would be flexible enough to deal with the dynamic environment that EC2 provides. However, I pretty quickly found that the existing dynamic DNS APIs of most of the providers were not up to the task of programmatically updating a DNS record the way I needed. Specifically, I wanted to be able to register and deregister an EC2 instance with a round robin A record automatically upon instance startup and shutdown.

In the end, I was only able to find one dynamic DNS provider whose API was up to this task: Nettica.

Once I found them, it was pretty easy to wrap their SOAP-based API into a binary to drive this type of dynamic management of my DNS records. Apache Axis took care of turning the WSDL into Java (the only library that could do so across three programming languages, by the way) and the code for driving that wrapper was pretty simple. The end result of that effort is now open sourced for all to use.

The way I use the new Nettica client is to have the init script automatically register an instance on startup with the Nettica service. However, I remove the instance from Nettica a bit before shutting down the instance itself in order to deal with DNS caches that sustain the now-removed IP for longer than the specified TTL value. You might be able to automate this by throwing a sleep LARGENUMBER into the shutdown portion of the init script, but I haven’t tried this yet.

In any case, I hope people find this client helpful when using EC2. I look forward to hearing about experiences with it and improving it for others. I’m planning for a release pretty soon to add support for RPM packaging, as most of the AMIs used today appear to be RedHat RPM based. Watch this space for updates.

I’ve just released by code to update EC2 instances on start up and shut down with the Nettica DNS service. You can find it here:

http://code.google.com/p/netticadns/

With this code, you can set up your EC2 instances to automatically register/deregister themselves with the Nettica DNS service on start up and shut down. There’s no RPM packaging at this point, but there is a dpkg available for it.

I’d appreciate any feedback or patches. Have fun with it :)