Chef
Configuration management tool which uses a pure-Ruby, domain-specific language (DSL) for writing system configuration recipes. Supports Linux, UNIX, Windows, and AIX as first-class citizens for management.
linux windows open-source provisioning config-mgmt ruby
Fog
The Ruby Cloud API library. Provides a Ruby API for interacting and managing many cloud providers, such as spinning up new instances, terminating old ones, attaching storage, etc. Currently supports more than 20 providers, including EC2, Rackspace, Brightbox, etc.
linux windows osx open-source cloud-paas ruby
MCollective
Marionette Collective (MCollective) is an orchestration framework built on top of Puppet. It can interact with a large number of servers (using a pub-sub middleware) and can execute jobs in parallel
linux windows osx free orchestration ruby
Orc
A model driven orchestration tool for deployment of application clusters
linux windows osx open-source provisioning orchestration ruby
Pallet
A tool to provision and maintain servers across various cloud platforms as well as virtual machine platforms, without any dependencies. Provides cloud and operating system independence.
linux windows osx open-source cloud-paas clojure
Soloist
Soloist lets you quickly and easily converge Chef recipes using chef-solo.
linux windows osx open-source provisioning ruby
Vagrant
Vagrant is a cross platform tool to create, boot, configure and destroy development environments. It provides a simple configuration-based approach to take a base image, boot it up, provision it (using any other provisioners), SSH, port forward, and much more. It automates the process of booting up and configuring virtual machines. It supports various providers like VirtualBox, VMWare, AWS, LXC, etc.
linux windows osx open-source virt provisioning ruby