Buildstep
Buildstep uses Docker and small buildpack scripts to build applications like Heroku. It was used by Dokku to create a 100-line Heroku clone. There are many open source Buildpack scripts for various languages like Java, Ruby, Erlang, PHP, etc.
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Eucalyptus
An open source software for building Amazon EC2-compatible private and hybrid cloud platforms
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FastForward
Flexible operating-system event and metric forwarding agent. Receives input and forwards output using plugins.
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Fig
A package management tool, similar to Ivy/APT, but language agnostic, faster and works well with both executables and libraries.
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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.
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Foreman
A complete lifecycle management tool for servers, both self-hosted and in the cloud. It allows you to create and manage instances, build and deploy images, view and audit hosts, and much more! It works with Puppet or Chef, and has multiple interaction facilities like a web frontend, CLI and a RESTful API.
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FPM
Effing Package Managers (FPM) is a single tool that can generate rpm, deb, solaris, osx (pkg) and many other packages. It supports multiple inputs (directory, gem, egg, deb, etc) and can produce multiple outputs (rpm, deb, solaris, etc). It relieves the pain out of creating various kinds of packages.
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Gauntlt
Gauntlt provides hooks to a variety of security tools and puts them within reach of security, dev and ops teams to collaborate to build rugged software. It is built to facilitate testing and communication between groups and create actionable tests that can be hooked into your deploy and testing processes.
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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.
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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!
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