Introduction to Ansible

Ansible is a software platform for configuring and managing computers. It combines multi-node software deployment, ad hoc tasks execution and configuration management.

Salient Features:

ØDocumented and reusable machine configuration
     Øwritten in Ansible playbooks.

ØAgentless
     ØNo client daemon required on target machines.

ØIdempotent
     ØCode defines states instead of actions.

ØMulti-node orchestration
     ØConfigure many nodes simultaneously.

 

Why Ansible

It is a free open source application

Agent-less – No need for agent installation and management

Phython/yaml based

Highly flexible and configuration management of systems.

Large number of ready to use modules for system management

Custom modules can be added if needed

Configuration roll-back in case of error

Simple and human readable

Self documenting.

 

Ansible: getting started

Installing:

$ (sudo) pip install ansible [--upgrade]

Can install via apt, yum, pkg, Homebrew in addition to from source

 

Configuration of ansible

 Ansible has a configuration & default inventory file used to define which servers it will be managing
Create a inventory file with list of client machines you wish to access via this server under /etc/ansible/hosts. Below is sample inventory file.

[Servers]

192.168.85.135

192.168.85.136

 [Local]

127.0.0.1

 [Prod Server]

114.9.75.65

114.9.75.63

114.9.75.61

Run the ping command below to see if indeed you are reaching both client nodes

$ ansible -m ping all

÷all - Use all defined servers from the inventory file.

÷-m ping - Use the "ping" module, which simply runs the ping command and returns the results.

 Ansible: structure

Ansible uses playbooks written in the YAML language for orchestration

Inventory file = definition of your architecture

÷Static / dynamic supported

Playbooks

÷can run multiple Tasks and provide some more advanced functionality that we would miss out on using ad-hoc commands

Roles

÷Roles are good for organizing multiple, related Tasks and encapsulating data needed to accomplish those Tasks.

Roles have a directory structure like this:

  Files

        Handlers

        Meta

        Templates

        Tasks

        Variables

 

Ansible: further reading / meta

Ansible Tower

¡Front end to Ansible

¡Manage team privs etc.

¡RESTful API

¡Audit, scheduled jobs etc.

¡Fairly expensive

Ansible Galaxy

¡out-the-box Ansible roles

¡don't have to reinvent the wheel each time

¡still relatively new so not too mature

¡installed via simple CLI.

 

For more information, please refer below links:

Ansible Docs: http://docs.ansible.com/

How Ansible is helpful in SDN - Openstack space:

Openstack: http://docs.openstack.org/developer/openstack-ansible/