I am pleased that one of my work in Wonga the rubyjobbuilderdsl is now opensource https://github.com/ wongatech/rubyjobbuilderdsl. It is a small internal domain specific language that can be used to automate provision and ongoing maintenance of Jenkins ecosystem.
It is used quite extensively within Wonga for a while and proves to be effective and convenient way to maintain complex Jenkins system with hundred of interconnected jobs you can read more about it in https://github.com/wongatech/rubyjobbuilderdsl/blob/master/docs/overview.md.