Two-year-old Engine Yard, the cloud start-up where Amazon has parked some investment money, is broadening the application-centric widgetry used to power its own proprietary cloud to - you guessed it - Amazon's EC2, its first step, it says, to becoming completely trans-cloud.

Its newfangled Solo lifecycle technology will extend the Engine Yard Ruby-on-Rails stack that started on its internal cloud to Amazon Web Services (AWS).

CEO Tom Mornini says Engine Yard's cloud, in operation for the last two years, currently supports 400 customers, 500 applications and 2,000-3,000 virtual machines. Extending Solo to Amazon will give customers a shot at a cheaper infrastructure, something Engine Yard calls an "entry-level solution" for deploying and managing Ruby application in the cloud.

The hazard is support is limited to forums and guides.

Anyway, Solo is scheduled to be available on Amazon on January 28 and unlike Engine Yard's own cloud, which costs a minimum of $400 a month, Solo on EC2 is supposed to run $129 a month plus whatever Amazon's meter says it costs for bandwidth and file storage.

Solo provides one instance per environment up to a maximum three environments and the $129 minimum monthly usage fee covers a full month's use of a single compute instance with default storage. There's no setup fee.

Engine Yard says a user gets essential infrastructure services such as persistent storage, web-based Gem installs, data backup/restore and system monitoring. All provisioning and monitoring is done through a self-service customer portal.

Engine Yard's software stack consists of nginx+mongrel and apache+passenger; Ruby on Rails application packages; Gentoo Linux; MySQL; and a pre-configured firewall. Users have full SSH-based access to their instances.

The start-up has another trick up its sleeve as well. It's open sourcing some widgetry called Vertebra to realize the idea of getting clouds to work with one another faster.

It describes it as a "platform for the cloud" aimed at programmers and system administrations who want to write scalable, manageable applications for the cloud and says it can be used to automate the cloud as well as for writing distributed real-time apps.

Engine Yard claims it can "embrace the difference of many clouds" and automate processes and application management.

Features include a standard XMPP infrastructure; a security and discovery agent to manage security policy; a process automation agent to orchestrate operational tasks involving both machines and people; a system provisioning registry so applications can be self-organizing; a federated design so apps can operate seamlessly and securely - sorta like e-mail; distributed auditing/logging; and distributed job control for operational awareness.

Mornini compares Vertebra to SOA in the cloud and says it will eliminate system administration.

There's an early release of Vertebra, licensed under the Lesser GPL, at http://vertebra.engineyard.com.

Engine Yard was in bootstrap mode for 15 months with its hosting business until this time last year when it got a $3.5 million A round from Benchmark Capital, followed only six months later by a $15 million B round from New Enterprise Associates, Amazon and Benchmark again.

The second round was meant to accelerate its business and pay for its cloud cluster R&D.

The company has 72 employees scattered about in Canada, Europe, Israel, Australia, New Zealand and the Philippines, with most of them in San Francisco.