Ansible (software)

Ansible is an open-source software provisioning, configuration management, and application-deployment tool enabling infrastructure as code.[2] It runs on many Unix-like systems, and can configure both Unix-like systems as well as Microsoft Windows. It includes its own declarative language to describe system configuration. Ansible was written by Michael DeHaan and acquired by Red Hat in 2015. Ansible is agentless, temporarily connecting remotely via SSH or Windows Remote Management (allowing remote PowerShell execution) to do its tasks.

This article is about the software named Ansible. For other uses, see Ansible (disambiguation).
Ansible
Original author(s)Michael DeHaan
Developer(s)Ansible Community / Ansible Inc. / Red Hat Inc.
Initial releaseFebruary 20, 2012 (2012-02-20)
Stable release
2.10.5 / January 19, 2021 (2021-01-19)[1]
Repository
Written inPython, PowerShell, Shell, Ruby
Operating systemLinux, Unix-like, MacOS, Windows
Available inEnglish
TypeConfiguration management, infrastructure as code (IaC), Orchestration engine
LicenseProprietary / GNU General Public License
Websitewww.ansible.com 

History

The term "ansible" was coined by Ursula K. Le Guin in her 1966 novel Rocannon's World,[3] and refers to fictional instantaneous communication systems.[4][5]

The Ansible tool was developed by Michael DeHaan, the author of the provisioning server application Cobbler and co-author of the Fedora Unified Network Controller (Func) framework for remote administration.[6]

Ansible, Inc. (originally AnsibleWorks, Inc.) was the company set up to commercially support and sponsor Ansible.[7][8] Red Hat acquired Ansible in October 2015.[9][10]

Ansible is included as part of the Fedora distribution of Linux, owned by Red Hat, and is also available for Red Hat Enterprise Linux, CentOS, openSUSE, SUSE Linux Enterprise, Debian, Ubuntu, Scientific Linux, and Oracle Linux via Extra Packages for Enterprise Linux (EPEL), as well as for other operating systems.[11]


Architecture

Unlike most configuration-management software, Ansible does not require a single controlling machine where orchestration begins.[12] Ansible works against multiple systems in your infrastructure by selecting portions of Ansible's inventory, stored as edit-able, version-able ASCII text files. Not only is this inventory configurable, but you can also use multiple inventory files at the same time and pull inventory from dynamic or cloud sources or different formats (YAML, INI, etc.).[13] Any machine with Ansible utilities installed can leverage a set of files/directories to orchestrate other nodes. The absence of a central-server requirement greatly simplifies disaster-recovery planning.[12] Nodes are managed by this controlling machine – typically over SSH. The controlling machine describes the location of nodes through its inventory.[13] Sensitive data can be stored in encrypted files using Ansible Vault[14] since 2014.[15] In contrast with other popular configuration-management software — such as Chef, Puppet, and CFEngine — Ansible uses an agentless architecture,[16] with Ansible software not normally running or even installed on the controlled node.[16] Instead, Ansible orchestrates a node by installing and running modules on the node temporarily via SSH. For the duration of an orchestration task, a process running the module communicates with the controlling machine with a JSON-based protocol via its standard input and output.[17] When Ansible is not managing a node, it does not consume resources on the node because no daemons are executing or software installed.[16]

Design goals

The design goals of Ansible include:[17]

  • Minimal in nature. Management systems should not impose additional dependencies on the environment.[16]
  • Consistent. With Ansible one should be able to create consistent environments.
  • Secure. Ansible does not deploy agents to nodes. Only OpenSSH and Python are required on the managed nodes.[16][12]
  • Highly reliable. When carefully written, an Ansible playbook can be idempotent, to prevent unexpected side-effects on the managed systems.[18] It is entirely possible to have a poorly written playbook that is not idempotent.
  • Minimal learning required. Playbooks use an easy and descriptive language based on YAML and Jinja templates.

Modules

Modules[19] are 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.[17]

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 or YAML format,[20] 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 inventory:

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.

Ansible can also use a custom Dynamic Inventory script, which can dynamically pull data from a different system, [21] and supports groups of groups.[22]

Playbooks

Playbooks are YAML files that express configurations, deployment, and orchestration in Ansible,[23] and allow Ansible to perform operations on managed nodes. Each Playbook maps a group of hosts to a set of roles. Each role is represented by calls to Ansible tasks.[24]

Ansible Tower

Ansible Tower is a REST API, web service, and web-based console designed to make Ansible more usable for IT teams with members of different technical proficiencies and skill sets. It is a hub for automation tasks. Tower is a commercial product supported by Red Hat, Inc. but derived from AWX upstream project, which is open source since September 2017.[25][26][27][28]

There was also another open source alternative to Tower, Semaphore, written in Go[29][30]

Platform support

Control machines have to be a Linux/Unix host (for example SUSE Linux Enterprise, Red Hat Enterprise Linux, Debian, CentOS, macOS, BSD, Ubuntu[11]), and Python 2.7 or 3.5 is required.[31]

Managed nodes, if they are Unix-like, must have Python 2.4 or later. For managed nodes with Python 2.5 or earlier, the python-simplejson package is also required.[32] Since version 1.7, Ansible can also manage Windows[33] nodes.[32] In this case, native PowerShell remoting supported by the WS-Management protocol is used, instead of SSH.

Cloud integration

Ansible can deploy to bare metal hosts, virtualized systems and cloud environments, including Amazon Web Services, Atomic, Lumen, Cloudscale, CloudStack, DigitalOcean, Dimension Data, Docker, Google Cloud Platform, KVM, Linode, LXC, LXD, Microsoft Azure, OpenStack, Oracle Cloud, OVH, oVirt, Packet, Profitbricks, PubNub, Rackspace, Scaleway, SmartOS, SoftLayer, Univention, VMware, Webfaction, and XenServer.[17][34]

AnsibleFest

AnsibleFest is an annual conference of the Ansible community of users, contributors, etc.[35]

Year Location
2016 London
2016 San Francisco
2016 Brooklyn
2017 London
2017 San Francisco
2018 Austin, Texas
2019 Atlanta
2020 Virtual only due to COVID-19 pandemic

See also

References
  1. "Releases – ansible/ansible". Retrieved 29 January 2021 – via GitHub.
  2. Staff writer. "Overview – How Ansible Works". ansible.com. Red Hat, Inc. p. 1. Retrieved December 7, 2016.
  3. Bernardo, Susan; Murphy, Graham J (2006). Ursula K. Le Guin : a critical companion. Westport, Conn: Greenwood Press. p. 18. ISBN 9780313027307. OCLC 230345464.
  4. Ansible Community. "Frequently Asked Questions". docs.ansible.com. Ansible Documentation. Red Hat, Inc. p. 1. Retrieved April 30, 2013.
  5. DeHaan, Michael (January 29, 2014). "Google Groups Post – Ansible Project". groups.google.com. p. 1. Retrieved April 26, 2017.
  6. Maughan, Mike (April 17, 2012). "An Interview with Ansible Author Michael DeHaan". coloandcloud.com. Maughansem LLC. p. 1. Archived from the original on November 14, 2012. Retrieved November 5, 2012.
  7. "About Ansible". Ansible, Inc. p. 1. Archived from the original on September 5, 2015. Retrieved July 8, 2016.
  8. Bloomberg Research. "Ansible, Inc.: Private Company Information". Internet Software and Services. Bloomberg L.P. p. 1. Retrieved July 8, 2016.
  9. Novet, Jordan (October 15, 2015). "Source: Red Hat is buying Ansible for more than $100M". venturebeat.com. VentureBeat, Inc. p. 1. Retrieved October 16, 2015.
  10. Staff writer (October 16, 2015). "Red Hat to Acquire IT Automation and DevOps Leader Ansible". redhat.com. Red Hat, Inc. Retrieved October 16, 2015.
  11. Ulianytskyi, Mykola. "ansible Download (DEB, RPM, TGZ, TXZ, XZ)". pkgs.org. Linux Packages Search. p. 1. Retrieved November 5, 2012.
  12. "Installation Guide — Ansible Documentation". docs.ansible.com. Retrieved 2018-11-30.
  13. Ansible Community. "Inventory". docs.ansible.com. Ansible Documentation. Red Hat, Inc. p. 1. Retrieved April 26, 2014.
  14. "Ansible Vault — Ansible Documentation". docs.ansible.com.
  15. "Ansible vault: a framework for encrypting any playbook or var file. · ansible/ansible@427b8dc". GitHub.
  16. "The Benefits of Agentless Architecture" (PDF). Red Hat, Inc. p. 5.
  17. "Ansible in Depth" (PDF). Red Hat, Inc. p. 5.
  18. "Achieving Rolling Updates and Continuous Deployment with Zero Downtime" (PDF). Red Hat, Inc. p. 7.
  19. "Module Index — Ansible Documentation". docs.ansible.com.
  20. "Working with Inventory — Ansible Documentation". docs.ansible.com. Retrieved 2018-11-30.
  21. Ansible Community. "Dynamic Inventory". docs.ansible.com. Ansible Documentation. Red Hat, Inc. p. 1. Retrieved November 25, 2016.
  22. "How to build your inventory — Ansible Documentation". docs.ansible.com.
  23. Ansible Community. "Playbooks". docs.ansible.com. Ansible Documentation. Red Hat, Inc. p. 1. Retrieved April 26, 2014.
  24. Ansible Community. "Task And Handler Organization For A Role". docs.ansible.com. Ansible Documentation. Red Hat, Inc. p. 1. Retrieved November 25, 2016.
  25. Redditors (February 19, 2016). "Ansible announces Tower to be Open Source in the near future on AnsibleFest!". reddit.com. Reddit. p. 1. Retrieved July 20, 2017.
  26. Staff writer. "The Open Tower Project". ansible.com/open-tower. Red Hat, Inc. p. 1. Retrieved January 21, 2017.
  27. Hat, Ansible, Red. "AWX Project FAQ | Ansible.com". www.ansible.com.
  28. "ansible/awx". March 25, 2020 – via GitHub.
  29. Semaphore community. "Semaphore API". ansible-semaphore.github.io. p. 1. Retrieved Feb 5, 2021.
  30. Semaphore community. "ansible-semaphore". github.com/ansible-semaphore. Castaway Consulting LLC. Retrieved Feb 5, 2021.
  31. Ansible Community. "Python 3 Support". docs.ansible.com. Ansible Documentation. Red Hat, Inc. p. 1. Retrieved July 6, 2017.
  32. Ansible Community. "Getting started". docs.ansible.com. Ansible Documentation. Red Hat, Inc. p. 1. Retrieved February 6, 2014.
  33. DeHaan, Michael (August 6, 2014). "Ansible 1.7 is released – Windows beta and more!". ansible.com/blog. The Inside Playbook. Ansible, Inc. p. 1. Retrieved August 7, 2014.
  34. Ansible Community. "List of cloud modules". docs.ansible.com. Ansible Documentation. Red Hat, Inc. p. 1. Retrieved April 28, 2017.
  35. "AnsibleFest". Ansible. Red Hat, Inc. Retrieved October 4, 2018.
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