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
Orc
A model driven orchestration tool for deployment of application clusters
linux windows osx open-source provisioning orchestration ruby
Puppet
Puppet is a tool designed to manage the configuration of Unix-like and Microsoft Windows systems declaratively.
linux windows osx open-source config-mgmt ruby
Rex
A agent-less server orchestration tool built on Perl
linux windows osx open-source orchestration perl