What is Ansible
Updated on 18th Oct, 21 3703 Views

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What is Ansible?

To understand Ansible meaning in an easy way, let us look at its past and see how it has helped system administrators to be more agile at work. 

On one hand, the developers were agile and were building and deploying code very frequently. The system administrators, on the other hand, were often lagged behind due to the constantly configuring systems. Although there were many configuration management tools like Puppet, Chef, Saltstack, Juju, CFEngine, none did the heavy lifting.

If the system administrator needed to install 8 servers out of which 4 servers were web servers and the remaining were database servers then they had to install Tomcat to web servers and MySQL to database servers. The installation of multiple types of servers to perform different operations was an exhaustive task. The entire installation process also consisted of installing media players and involved a lot of intricate steps. 

This is where the prowess of Ansible comes into the picture and solves one of the major problems of multiple installations of servers. Using Ansible, it was easy to communicate the configurations in a single system and the server. 

Here is a brief about the 3 types of tasks that Ansible automates:

Provisioning – This tool can be used to set up servers in the target infrastructure.

Application deployment – By automating the deployment to your production systems of internally developed applications DevOps is made way easier.

Configuration management – Alter configuration of an application, device, install or update applications, implement a security policy, OS, device, start and stop services. These is only some of the configuration tasks that can be done.

Irrespective of whether Ansible is hosted on the traditional servers, cloud, or virtualization platforms, it is highly efficient to automate IT environments. This Ansible config is also possible across various storage devices, firewalls, databases, etc. One of the interesting features that Ansible offers is that the user does not have to know the commands to perform a particular task. Only specifying what state a user needs to attain is enough!

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What is Ansible in DevOps?

Ansible is the most preferred DevOps tool that is easily deployable and it neither requires agents nor additional custom security infrastructure. It is comparatively easy to use since the automation engine works with YAML Ain’t Markup Language which requires simple English as input.

Ansible for DevOps automates several IT needs such as cloud provisioning, configuration management, application deployment, and intra-service orchestration. This in effect provides benefits such as faster deployments, coordinated IT infrastructure, reliable deployments, faster feedback, and quick finding of bugs.

Ansible architecture

Ansible architecture

The playbooks in Ansible are written in Yet Another Markup Language (YAML). It is a human-readable data serialization language and declarative in nature. Playbooks contain task(s) and are expressed either with core modules or custom modules that are written for special situations.  The plays(tasks) are done from top to bottom. As Ansible runs on Python, the remote servers should have the language installed.

To learn  more about Ansible, check out this Ansible Tutorial!

How playbooks come into play in Ansible?

Playbooks are the language for Ansible’s configuration, deployment, and orchestration. They describe a policy as to how remote systems should be enforced, or a set of steps in a general IT process. If Ansible modules are the tools in the admin’s workshop, playbooks are his instruction manuals, and his inventory of hosts is simply his raw material.

Basically, playbooks are used to manage configurations of remote machines and their deployments. At a more advanced level, they can sequence multi-tier rollouts involving rolling updates. They can also delegate actions to other hosts, interact with monitoring servers and load balancers.

Ansible vs Puppet

Let’s look into how these robust configuration management (CM) tools differ from one another in this tutorial on Ansible.

Ansible Puppet
Push vs pull Follows push workflow The client software in Puppet nodes periodically check Puppet master server to pull resource definitions
Server nodes No special master agent of special agent executables to install There are more than 1 puppetmaster servers along with special agent packages installed on each client node
Language extensibility Built on Python Built on Ruby and Ruby ecosystem is used to test Puppet applications
Syntax Ansible playbooks are YAML files Puppet’s domain specific language is a subset of Ruby.
Template language Based on Jinja2 which is a subset of Django’s templating language Based on ruby’s ERB
Resources and ordering Playbooks are applied top-to-bottom as they appear in file Resources defined in Puppet are usually not applied in order of their appearance

Chef vs Ansible

In this Ansible tutorial let’s look into how the tool compares with yet another CM tool called Chef.

Ansible Chef
Workflow management Seamless. What one sees on disk is what one deploys. Relatively difficult.
Maintenance Known for least maintenance Server and client component have to be periodically upgraded
Inventory Uses inventory scripts against EC2, rackspace to put out a list of hosts and groups Nodes are registered with the server and will be part of the search
Simplicity Simplest CM tool Relatively sophisticated CM tool

Various concepts of Ansible

Let’s get a good grounding on various key concepts of Ansible.

Templates

A template file in Ansible is nothing but a text file with a .j2 extension. They are those files that are used to make the configuration files more dynamic.

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Modules

The understanding of how Ansible works can be gained by connecting many nodes and pushing out small programs called ansible modules. Ansible comes with a number of such modules that can be executed directly on remote hosts or through playbooks. System resources like packages, services, or even files can be controlled by modules. They are also instrumental in handling system commands. 

Ansible service module controls services on remote hosts. Ansible command module takes as input the command name and also a list of space-delimited arguments and the given command will be executed on all nodes but not on the shell. 

Ansible modules can be written by users.  The user module of Ansible manages user accounts and user attributes. The shell module in Ansible also works by taking as input the command name followed by a list of space-delimited arguments just like the command module. 

There are various file modules in Ansible like Acl, archive, copy, fetch, file, find, iso_extract, lineinfile, patch, replace, stat, synchronize, tempfile, template, unarchive, xattr, xml.

Learn about the important terminologies in our blog on Ansible Cheat Sheet!

Handlers

They are those lists of tasks that are referenced by a globally unique name and are notified by notifiers. The handler will not run if nothing notifies it. Irrespective of how many tasks notify the handler it runs only once and that too after all tasks complete in a particular play.

Commands

There areplethora of commands in Ansible but we’ll just give you a sample of a generic command.

$ ansible <group> -m <module> -a <arguments>

The above command is the syntax of complete command. In place of<group> we can either use a single host or all. <arguments> are optional to provide.

When command

When you want to omit a step on a host then this command is used. While installing certain packages can be skipped as per certain conditions or cleanup processes can be coded when the filesystem is getting full. It is easy to accomplish in Ansible with its when clause

Ansible code example
tasks:

Name: “close down Debian flavoured systems”
command: /sbin/shutdown -t now
when: ansible_os_family == "Debian"

Installation in Linux

Compared to other configuration management tools the installation and setup of Ansible are really easy. Quite a number of distributions have a package in their 3rd party repositories that can be easily installed. Creating a user and all notifying needs of Ansible can all be achieved with ease.

The yum command which follows is enough to install Ansible.

$ sudo yum install Ansible

Shell

The command name is taken by the shell module followed by some space-delimited arguments. It is quite similar to the command module but it runs the commands through the command module through a shell on the remote node. Win_shell module is used for windows targets.

Inventory

This CM tool can be made to run in one’s infrastructure against multiple systems at the same time. To accomplish this, portions of systems listed in Ansible’s inventory are selected which by default gets saved in location /etc/ansible/hosts. A different inventory file can be specified using the -I <path> on the command line.

APT

APT expanded is an Advanced packaging tool which is the preferred Ansible package management toolset in Ubuntu. Packages can be installed, updated and also removed through this management toolset.

Copy file

To copy a file from the local or remote machine to a location on the remote machine copy module is used. The fetch module copies files from remote locations to the local box.

Script

Script name along with a list of space-delimited arguments is taken by the script module. In path whatever local script is there, it will get transferred to the remote node and get executed.

Read the difference between Terraform and Ansible in our comparison blog on Terraform vs Ansible.

Ansible advantages

In the CM world, there are alternatives for Ansible like Puppet, Chef, Saltstack and many others. But let’s see what benefits Ansible deployment really gives out.

  • Ansible has fewer dependencies and therefore it is more stable and also very fast to implement. The user of Ansible who intends to host a very large infrastructure can do so without worry due to the efficiency of this tool.
  • Ansible is agentless. An agent is a program that has to be installed on the remote system in order to work with it. It is also due to this virtue that you can quickly carry out your tasks with this tool.
  • There is no database because of which it is highly portable. You can move it from system to system and not have to worry about having to set up a database. Consequently, you don’t require a DBA (Database administrator) to manage performance or backups or dealing with software upgrades when you’re upgrading the infrastructure.
  • After you run your playbooks on your remote systems the software needed to run the playbooks is gone. After a piece of software accomplishes its task it is then gone. Hence there is no residual software.
  • As there are no dependencies on other systems upgrading Ansible is very easy. There are no schema updates on a database server or deployment of agent upgrades. You just change the upgrade to the Ansible code on your control system and the upgrade is done.

Learn about the important terminologies in our blog on Ansible Cheat Sheet!

Conclusion

The Ansible tool as specified came in 2012 and became known for its simplicity. It is one of the defining points of this tool. Of all the documentations on Puppet, Chef and Ansible, the last tool is the easiest to follow. Puppet and Chef require Ruby which is relatively hard to learn as compared to YAML used by Ansible. This is the reason why it is a great favourite among systems admins which you have known from this tutorial on Ansible. When DevOps roles become more and more specialized in the IT industryAnsible for DevOps trends will only increase. System administrators familiar with this tool will greatly be in demand.

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