As PaaS is becoming more prevalent than ever, most PaaS environments and frameworks are still strongly opinionated and allow for very limited control and extensibility.
Extending a PaaS framework requires deep understating of its internals at best, and in many cases in not even possible.
Cloudify, a new open source PaaS framework, has taken a different approach, by using recipes (As opposed to heavyweight coding and platform extension) as means to introduce new application stacks to the PaaS layer. You can think of it as extending the recipe model of Chef to support application level concerns, such as orchestration, dependency management, multi-tier and multi-host deployments, monitoring and autoscaling.
This presentation covers the foundations of Cloudify, and how it leverages Chef as a key enabler for an open PaaS framework.
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