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
jclouds
A Java Library for controlling cloud resources, with various plugins for many popular cloud providers.
linux windows osx open-source cloud-paas java
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
SSH KeyBox
An open-source jump box solution with auditing capabilities
linux open-source cloud monitoring security java
Apache ZooKeeper
ZooKeeper is a centralized service for maintaining configuration information, naming, providing distributed synchronization, and providing group services. It is distributed and highly reliable, with Consensus, group management and presence protocols built-in.
linux open-source service-discovery java