Introduction to ansible

Introduction to Ansible
Krishantha Dinesh Msc, MIEEE, MBCS
Software Architect
www.krishantha.com
www.youtube.com/krish
@krishantha

* http://www.krishantha.com * https://www.youtube.com/krish * https://www.linkedin.com/in/krish-din/
Configuration management
• Manage software on top of hardware
• Maintain consistency based on functionality and design
• It is systems engineering process for establishing and maintaining consistency of a product's performance

Why Configuration Management
• Make consistency
• Maintain integrity
• No need separate log in / execution on each server
• Centralize control / management
• Scaling made easy
• No time to deploy or configure after successful build
• Rolling back is easy

What is ansible
• Ansible is an open-source software provisioning, configuration management, and application-deployment tool.
• It runs on many Unix-like systems, and can configure both Unix-like systems as well as Microsoft Windows.
• Its pushed based configuration management tool

Why ansible
• Free. Ansible is an open-source tool.
• Very simple to set up and use. No special coding skills are necessary to use Ansible’s playbooks
• Powerful. Ansible lets you model even highly complex IT workflows.
• Flexible. You can orchestrate the entire application environment no matter where it’s deployed. You can also customize
it based on your needs.
• Agentless. You don’t need to install any other software or firewall ports on the client systems you want to automate.
You also don’t have to set up a separate management structure.
• Efficient. Because you don’t need to install any extra software, there’s more room for application resources on your
server.

Ansible Architecture
• Modules
• Modules are like small programs that Ansible pushes out from a control machine to all the nodes / remote hosts.
• The modules are executed using playbooks.
• They control things such as services, packages and files. Ansible executes all the modules for installing updates or
whatever the required task is, and then removes them when finished.
• Ansible provides 400+ modules for common tasks

• Plugins
• As many other tools and platforms, plugins are extra pieces of code that augment functionality.
• Ansible comes with a number of its own plugins.
• we can write your own as well.

• Inventory
• All the machines you’re using with Ansible (the control machine plus nodes) are listed in a single simple file, with
their IP addresses, names etc.
• Once you list the inventory, you can assign variables to any of the hosts using a simple text file.

• Playbook
• Ansible playbooks are like instruction manuals for tasks.
• They are simple files written in YAML. (human-readable data serialization language).
• Playbooks are really at the heart of what makes Ansible so popular because they describe the tasks to be done
easily and without the need for the user to know or remember any special syntax. Not only can they declare
configurations, but they can orchestrate the steps of any manually ordered task, and can execute tasks at the
same time or at different times.
• Each playbook is composed of one or multiple plays, and the goal of a play is to map a group of hosts to well-
defined roles, represented by tasks.

Ansible Tower
• Ansible Tower is Red Hat’s commercial web-based solution for managing Ansible.
• Its best-known feature is an easy-to-use UI for managing configurations and deployments,
• Ansible Tower contains the most important features of Ansible, especially those that are easier to see in a graphical
format rather than a text-based format.

Practical example
Ansible
installed
EC2
Manager
EC2 node1
10.0.81.10
EC2 node2
10.0.81.11
EC2 node1
10.0.81.12

Generate ssh key at Manager EC2
ssh-keygen

Copy public key to remote (to node 1-2-3)
• cat ~/.ssh/id_rsa.pub |ssh -i kkey.pem ec2-user@10.0.81.10 "cat - >>
~/.ssh/authorized_keys”
• Repeat above step to all 3 nodes

Install ansible on Manager
OR
OR in ubuntu

Every steps here onward to be execute on Manager (ansible installed instance)

Basic config
• Ansible by default install basic configs at /etc/ansible
• Good practice is copy that and work on copy

Configure hostfile
• Since we have taken a copy we need to configure which host file to be used
• Update ansible.cfg as follows

Update hosts

Verify [ad-hoc command]
• Now we can verify that ansible can use all hosts or not

Some more ad-hoc command
• Add-hoc commands are the command can use directly on terminal without configure
• -m à shell module
• -a à argument

Failed – need sudo access

-b sudo access –K ask sudu password

Verify user
With ansible
Without ansible

Roles
• Ansible will execute roles on target machines
• Palybook can determine which role to which target machine
• Role is directory under roles and need other directory call task and inside main.yml

Install a package
• nmap is not installed

Create main.yml

Create playbook

EXECUTE

verify
nmap installed

Configure additional packages

Additional packages

Variable substitution
• Ansible can replace values with variable.
• Lets see how we can use one install option and provide packages

Copy files
• Create sample file at /home/ec2-user/data.txt
vim roles/setup/tasks/main.yml

Execute and verify

Introduction to ansible

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