Ansible (software)

Ansible
Original author(s) Michael DeHaan
Developer(s) Ansible Community / Ansible Inc. / Red Hat Inc.
Initial release February 20, 2012 (2012-02-20)
Stable release
2.2.0.0 / November 1, 2016 (2016-11-01)[1][2]
Repository github.com/ansible/ansible
Development status Active
Written in Python
Operating system Linux, Unix-like, Windows
Available in English
Type Configuration management, Infrastructure as Code, Orchestration engine
License GNU General Public License
Website www.ansible.com

Ansible is a free-software platform for configuring and managing computers which combines multi-node software deployment, ad hoc task execution, and configuration management.[3] It manages nodes over SSH or over PowerShell.[4] Modules work over JSON and standard output and can be written in any programming language. The system uses YAML to express reusable descriptions of systems.[5]

Michael DeHaan, the author of the provisioning server application Cobbler and co-author of the Func framework for remote administration, developed the platform.[6] It is included as part of the Fedora distribution of Linux, owned by Red Hat Inc., and is also available for Red Hat Enterprise Linux, CentOS, and Scientific Linux via Extra Packages for Enterprise Linux (EPEL) as well as for other operating systems.[7]

Ansible, Inc. (originally AnsibleWorks, Inc.) was the company set up to commercially support and sponsor Ansible.[8][9] It was acquired by Red Hat in October 2015.[10][11]

The name "Ansible" references a fictional instantaneous hyperspace communication system (as featured in Orson Scott Card's Ender's Game (1985),[12] and originally invented by Ursula K. Le Guin for her novel Rocannon's World (1966)).

Architecture

As with most configuration management software, Ansible distinguishes two types of servers: controlling machines and nodes. First, there is a single controlling machine which is where orchestration begins. Nodes are managed by a controlling machine over SSH. The controlling machine describes the location of nodes through its inventory.[13]

To orchestrate nodes, Ansible deploys modules to nodes over SSH. Modules are temporarily stored in the nodes and communicate with the controlling machine through a JSON protocol over the standard output.[14] When Ansible is not managing nodes, it does not consume resources because no daemons or programs are executing for Ansible in the background.[15]

In contrast with popular configuration management software — such as Chef, Puppet, and CFEngine — Ansible uses an agentless architecture.[15] With an agent-based architecture, nodes must have a locally installed daemon that communicates with a controlling machine. With an agentless architecture, nodes are not required to install and run background daemons to connect with a controlling machine. This type of architecture reduces the overhead on the network by preventing the nodes from polling the controlling machine.[15]

Design goals

The design goals of Ansible include:[14]

Modules

Modules are considered to be the units of work in Ansible. Each module is mostly standalone and can be written in a standard scripting language (such as Python, Perl, Ruby, bash, etc.). One of the guiding properties of modules is idempotency, which means that even if an operation is repeated multiple times (e.g., upon recovery from an outage), it will always place the system into the same state.[14]

Inventory configuration

The Inventory is a description of the nodes that can be accessed by Ansible. By default, the Inventory is described by a configuration file, in INI format, whose default location is in /etc/ansible/hosts. The configuration file lists either the IP address or hostname of each node that is accessible by Ansible. In addition, nodes can be assigned to groups.[13]

An example configuration file:

192.168.6.1

[webservers]
foo.example.com
bar.example.com

This configuration file specifies three nodes. The first node is specified by an IP address and the latter two nodes are specified by hostnames. Additionally, the latter two nodes are grouped under the webservers group name.

Ansible can also be pointed towards a custom Dynamic Inventory script, which can pull data from any different software system.[16]

Playbooks

Playbooks express configurations, deployment, and orchestration in Ansible.[17] The Playbook format is YAML. Each Playbook maps a group of hosts to a set of roles. Each role is represented by calls to Ansible call tasks.[18]

Platform support

Control machines must have Python 2.6 or 2.7. Operating systems supported on control machines include most Linux and Unix distributions, such as Red Hat, Debian, CentOS, OS X, BSD, and Ubuntu, among others.[7]

Managed nodes must have Python 2.4 or later. For managed nodes with Python 2.5 or earlier, the python-simplejson package is also required.[4] Ansible can manage Windows[19] nodes starting from version 1.7.[4]

Cloud integration

Ansible can deploy to virtualization environments and public and private cloud environments, including Amazon Web Services, CloudStack, DigitalOcean, Eucalyptus Cloud, Google Cloud Platform, KVM, Microsoft Azure, OpenStack, Rackspace, SoftLayer, VMware, and XenServer.[14]

Big data integration

Ansible can deploy big data, storage, and analytics environments, including Hadoop, Riak, and Aerospike. In these environments, Ansible helps manage each node's resource consumption, consuming little CPU time and memory in the process. Furthermore, Ansible provides monitoring capabilities that measure such properties as available CPU resources, which can help in the supervision of these nodes.[14]

See also

References

  1. ↑ Ansible 2.2.0.0 on Python Package Index
  2. ↑ Ansible 2.2.0.0 on ansible.com
  3. 1 2 "Achieving Rolling Updates and Continuous Deployment with Zero Downtime" (PDF). Red Hat, Inc. p. 7.
  4. 1 2 3 Ansible Community. "Getting started". docs.ansible.com. Ansible Documentation. Red Hat, Inc. p. 1. Retrieved February 6, 2014.
  5. ↑ "Ansible: CM, Deployment, and Ad Hoc Task Execution All in One". DZone. April 18, 2012.
  6. ↑ Mike Maughan (April 17, 2012). "An Interview with Ansible Author Michael DeHaan". coloandcloud.com. Maughansem LLC. p. 1. Retrieved November 5, 2012.
  7. 1 2 Mykola Ulianytskyi. "ansible Download (DEB, RPM, TGZ, TXZ, XZ)". pkgs.org. Linux Packages Search. p. 1. Retrieved November 5, 2012.
  8. ↑ "About Ansible". Ansible, Inc. p. 1. Archived from the original on September 5, 2015. Retrieved July 8, 2016.
  9. ↑ Bloomberg Research. "Ansible, Inc.: Private Company Information". Internet Software and Services. Bloomberg L.P. p. 1. Retrieved July 8, 2016.
  10. ↑ Jordan Novet (October 15, 2015). "Source: Red Hat is buying Ansible for more than $100M". venturebeat.com. VentureBeat, Inc. p. 1. Retrieved October 16, 2015.
  11. ↑ "Red Hat to Acquire IT Automation and DevOps Leader Ansible". redhat.com. October 16, 2015. Retrieved October 16, 2015.
  12. ↑ Ansible Community. "Frequently Asked Questions". docs.ansible.com. Ansible Documentation. Red Hat, Inc. p. 1. Retrieved April 30, 2013.
  13. 1 2 Ansible Community. "Inventory". docs.ansible.com. Ansible Documentation. Red Hat, Inc. p. 1. Retrieved April 26, 2014.
  14. 1 2 3 4 5 "Ansible in Depth" (PDF).
  15. 1 2 3 4 5 "The Benefits of Agentless Architecture" (PDF). Red Hat, Inc. p. 5.
  16. ↑ Ansible Community. "Dynamic Inventory". docs.ansible.com. Ansible Documentation. Red Hat, Inc. p. 1. Retrieved November 25, 2016.
  17. ↑ Ansible Community. "Playbooks". docs.ansible.com. Ansible Documentation. Red Hat, Inc. p. 1. Retrieved April 26, 2014.
  18. ↑ Ansible Community. "Task And Handler Organization For A Role". docs.ansible.com. Ansible Documentation. Red Hat, Inc. p. 1. Retrieved November 25, 2016.
  19. ↑ "Ansible 1.7 is released - Windows beta and more!". August 7, 2014.

External links

This article is issued from Wikipedia - version of the 11/25/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.