Ansible
A versatile orchestration engine that can automate systems and apps. Instead of a custom scripting language or code, it is very simple and shell based. It is also agent-less, so you can just start using it right away and get things done
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Batou
Batou makes it easy to perform automated deployments. It combines Fabric's simplicty and SSH automation, with Puppet's declarative syntax and idempotence
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Bolt
Bolt is an open source orchestration tool that automates the manual work it takes to maintain your infrastructure. Use Bolt to automate tasks that you perform on an as-needed basis or as part of a greater orchestration workflow. For example, you can use Bolt to patch and update systems, troubleshoot servers, deploy applications, or stop and restart services. Bolt can be installed on your local workstation and connects directly to remote targets with SSH or WinRM, so you are not required to install any agent software.
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Brood
A Deployment framework written in PHP. Can deploy to multiple servers using Gearman.
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Buildbot
Buildbot is an open-source framework for automating software build, test, and release processes. It differs from other CI tools in that it is more of a betteries included Framework, rather than a tool, and can hence be grown to meet your own needs. One of the reasons it is used in many high profile open source projects like Chromium, Firefox, Webkit, Python, etc.
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