ultradns4r: A Ruby Library and Command Line Client for the Neustar UltraDNS SOAP API

I just spent the last week or so learning more about SOAP than I ever wanted to know. ;-) Fortunately, the result of that hard work resulted in something that might benefit the EC2 community.

I am pleased to announce ultradns4r; a Ruby library and command line client for the Neustar UltraDNS SOAP API. I created this tool to alleviate the pain in dealing with EC2’s dynamic hostnames and IP addresses. Since it allows editing of arbitrary DNS records via the command line, it can be used to make EC2 instances update their own DNS records.

Lessons Learned

• If you need to do SOAP in Ruby, just use Savon. Trust me on this.
• WSSE authentication is a complete pain in the ass. I was unable to find any SOAP library (Ruby, Python, or Perl) that could authenticate with the UltraDNS API servers out of the box (Savon included). I ended up having to build the entire WSSE header manually in order to generate the exact XML needed.
• Apparently, element order sometimes matters with SOAP! This is something I never expected, considering that (last I knew) the XML spec does not even allow you to enforce element or attribute order. This was also the cause of a lot of my WSSE problems. I found that for example, if the Password element came after the Nonce and Created elements (which is the case if you use Savon’s built-in WSSE authentication), then authentication would fail. Could this have been the result of having a buggy XML parser on the server side? In any case, this is one of those annoying issues to be aware of.