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.
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FastForward
Flexible operating-system event and metric forwarding agent. Receives input and forwards output using plugins.
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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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Instrumental
Instrumental is a real-time, high-scale application and server monitoring tool with intelligent alerts, a powerful query language, and free development accounts.
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Kibana
Kibana is a modern, beautiful visualization tool that works seamlessly with Logstash and ElasticSearch. It features a no-code setup, realtime analytics, and much more.
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MCollective
Marionette Collective (MCollective) is an orchestration framework built on top of Puppet. It can interact with a large number of servers (using a pub-sub middleware) and can execute jobs in parallel
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Orc
A model driven orchestration tool for deployment of application clusters
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Puppet
Puppet is a tool designed to manage the configuration of Unix-like and Microsoft Windows systems declaratively.
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Rex
A agent-less server orchestration tool built on Perl
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