PUPPET

 PUPPET

 Puppet is a software configuration management tool which includes its own declarative language to describe system configuration. It is a model-driven solution that requires limited programming knowledge to use.

Puppet is produced by Puppet Inc., founded by Luke Kanies in 2005. Its primary product, Puppet Enterprise is a proprietary and closed-source version of its open-source Puppet software. They use Puppet's declarative language to manage stages of the IT infrastructure lifecycle, including the provisioning, patching, configuration, and management of operating system and application components in data centers and cloud infrastructures.

Puppet uses an open-core model; its free-software version was released under version 2 of the GNU General Public License (GPL) until version 2.7.0, and later releases use the Apache License, while Puppet Enterprise uses a proprietary license.

Puppet and Puppet Enterprise operate on multiple Unix-like systems (including Linux, Solaris, BSD, Mac OS X, AIX, http://HP-UX) and has Microsoft Windows support. Puppet itself is written in Ruby, while Facter is written in C++, and Puppet Server and Puppet DB are written in Clojure.

Design

Puppet is designed to manage the configuration of Unix-like and Microsoft Windows systems declaratively. The user describes system resources and their state, either using Puppet's declarative language or a Ruby DSL (domain-specific language). This information is stored in files called "Puppet manifests". Puppet discovers the system information via a utility called Facter, and compiles the Puppet manifests into a system-specific catalog containing resources and resource dependency, which are applied against the target systems. Any actions taken by Puppet are then reported.

Puppet consists of a custom declarative language to describe system configuration, which can be either applied directly on the system, or compiled into a catalog and distributed to the target system via client–server paradigm (using a REST API), and the agent uses system specific providers to enforce the resource specified in the manifests. The resource abstraction layer enables administrators to describe the configuration in high-level terms, such as users, services and packages without the need to specify OS specific commands (such as rpm, yum, apt).

Puppet is model-driven, requiring limited programming knowledge to use.

It comes in two versions, Puppet Enterprise and Open Source Puppet. In addition to providing functionalities of Open Source Puppet, Puppet Enterprise also provides GUI, API and command line tools for node management.

Architecture                                                                                                                                                                                   

Puppet usually follows client-server architecture. The client is known as an agent and the server is known as the master. For testing and simple configuration, it can also be used as a stand-alone application run from the command line.

Puppet Server is installed on one or more servers, and Puppet Agent is installed on all the machines to be managed. Puppet Agents communicate with the server and fetch configuration instructions. The Agent then applies the configuration on the system and sends a status report to the server. Devices can run Puppet Agent as a daemon, that can be triggered periodically as a cron job or can be run manually whenever needed.

The Puppet programming language is a declarative language that describes the state of a computer system in terms of "resources", which represent underlying network and operating system constructs. The user assembles resources into manifests that describe the desired state of the system. These manifests are stored on the server and compiled into configuration instructions for agents on request.