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
ConDep
ConDep is a open source infrastructure configuration and deployment DSL (Domain Specific Language) specifically targeted to (but not limited to) the Windows Server platform. If your familiar with tools like Chef and Puppet, ConDep does very much the same, but with native support for Windows.
windows open-source ci provisioning config-mgmt net
Consul
Consul makes it simple for services to register themselves and to discover other services via a DNS or HTTP interface. Register external services such as SaaS providers as well
linux windows osx open-source service-discovery go monitoring
FastForward
Flexible operating-system event and metric forwarding agent. Receives input and forwards output using plugins.
linux windows osx open-source metrics monitoring ruby
Fig
A package management tool, similar to Ivy/APT, but language agnostic, faster and works well with both executables and libraries.
linux windows osx open-source packaging ruby
Instrumental
Instrumental is a real-time, high-scale application and server monitoring tool with intelligent alerts, a powerful query language, and free development accounts.
linux windows oxs free metrics commercial metrics monitoring visualization php ruby python net java nodejs
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
Vagrant Cachier
A Vagrant plugin that helps you reduce the amount of coffee you drink while waiting for boxes to be provisioned by sharing a common package cache among similiar VM instances.
linux windows osx open-source virt artifacts ruby
Veewee
veewee is a great tool for building Virtual Machine images (aka base boxes). It automates most of the steps and allows you to easily create readymade images for VirtualBox/Vagrant, VMWare Fusion, KVM and Parallels. No longer need to shy away from building custom VM images!
linux osx windows open-source virt packaging ruby