Ansible_1

 Playbook

In Ansible, a script is called a playbook. 

A playbook describes which hosts to configure, and an ordered list of tasks to perform on those hosts. 

The playbook can be execute by using the ansible-playbook command

Ansible’s playbook syntax is built on top of YAML

$ ansible-playbook <name>.yml

Ansible will make SSH connections in parallel

It will execute the first task on the list on all hosts simultaneously.

eg:- 1st tasks 

- name: Install nginx

  apt: name=nginx

Ansible will do the following:

1. Generate a Python script that installs the required package

2. Copy the script to host1, host2, and host3

3. Execute the script on host1, host2, and host3

4. Wait for the script to complete execution on all hosts

Ansible will then move to the next task in the list, and go through these same four steps. It’s important to note the following:

• Ansible runs each task in parallel across all hosts.

• Ansible waits until all hosts have completed a task before moving to the next task.

• Ansible runs the tasks in the order that you specify them.

Simple Terms

Ansible playbooks as executable documentation. It’s like the README file that describes the commands you had to type out to deploy your software, except that the instructions will never go out-of-date because they are also the

code that gets executed directly.

Remote Hosts

To manage a server with Ansible, the server needs to have SSH and Python 2.5 or later installed, or Python 2.4 with the Python simplejson library installed. 

There’s no need to preinstall an agent or any other software on the host.

Control machine 

The control machine (the one that you use to control remote machines) needs to have Python 2.6 or later installed

Ansible

Name Ansible

It’s a science-fiction reference

An ansible is a fictional communication device that can transfer information faster than the speed of light. 

Ursula K. Le Guin invented the concept in her book Rocannon’s World, and other sci-fi authors have since borrowed the idea from Le Guin.

Michael DeHaan took the name Ansible from the book Ender’s Game by Orson Scott Card. In that book, the ansible was used to control many remote ships at once, over vast distances. Think of it as a metaphor for controlling remote servers.

Michael DeHaan :- Creator of Ansible software

Ansible started as a simple side project in February of 2012

Configuration Management

we are typically about writing some kind of state description for our servers, and then using a tool to enforce that the servers are, indeed, in that state: the right packages are installed, configuration files contain the expected values and have the expected permissions, the right services are running, and so on.

Deployment

They are usually referring to the process of taking software that was written in-house, generating binaries or static assets (if necessary), copying the required files to the server(s), and then starting up the services.

Ansible is a great tool for deployment as well as configuration management.