What is Anisible ?

I. Introduction

A. Explanation of Ansible

Ansible is an open-source automation tool that can be used to configure, deploy, and manage servers, networks, and applications. It uses a simple, human-readable language called YAML to describe automation jobs, and it communicates with remote servers using SSH. Ansible can be used to automate tasks such as software installation, configuration management, and application deployment. Additionally, it can be used to manage cloud resources, containers, and network devices.

B. Purpose of Ansible

The purpose of Ansible is to automate the deployment, configuration, and management of servers, networks, and applications. It allows system administrators and developers to automate repetitive tasks, such as software installation, configuration changes, and application deployment. Ansible's simple, human-readable language (YAML) and use of SSH for communication make it easy to use and understand, even for those with limited technical experience. Additionally, Ansible's modular design allows users to easily extend its functionality to meet the specific needs of their organization. Overall, the purpose of Ansible is to improve efficiency, reduce errors, and save time in the management of IT infrastructure.

C. Advantages of using Ansible

There are several advantages of using Ansible for automation and configuration management:

Easy to use and understand: Ansible uses a simple, human-readable language (YAML) to describe automation jobs, making it easy for even those with limited technical experience to use and understand.

Agentless: Ansible does not require any additional software to be installed on the managed nodes, it uses SSH for communication.

Modular design: Ansible's modular design allows users to easily extend its functionality to meet the specific needs of their organization. This can be done by using existing modules or creating custom modules.

Idempotent: Ansible's idempotent nature means that it will only make the necessary changes to bring a system to the desired state, avoiding unnecessary changes and errors.

Large and active community: Ansible has a large and active community that provides support and shares resources such as playbooks, modules, and plugins.

Multi-platform support: Ansible can be used to manage a wide variety of platforms, including Linux, Windows, and network devices.

Flexible: Ansible can be used for a wide range of tasks, from simple ad-hoc commands to complex multi-tier deployments, and it can be integrated with other tools to create powerful automation workflows.

Cloud and container support: Ansible can be used to manage cloud resources and containers.

Overall, Ansible's simplicity, flexibility, and wide range of supported platforms and tasks make it a valuable tool for automating and managing IT infrastructure.

II. Ansible Architecture

A. Control Node

A control node is the machine where Ansible is installed and from where automation tasks are executed. The control node is responsible for running Ansible commands and playbooks, connecting to managed nodes, and gathering information about the state of the managed nodes. The control node must have Ansible installed, as well as the necessary dependencies and libraries.

The control node connects to the managed nodes using SSH, and it uses the inventory file to determine which nodes to connect to. The inventory file is a simple text file that lists the managed nodes, along with their IP addresses or hostnames, and any additional information that is needed to connect to them. The control node uses this information to establish an SSH connection with each managed node and run the specified Ansible commands or playbooks.

The control node also uses the Ansible configuration file (ansible.cfg) to set various options, such as the location of the inventory file, the user to connect as, and the private key to use for SSH connections.

In summary, the control node is the centralized point from where Ansible is run, it connects to the managed nodes, it uses the inventory and configuration files to know where to connect and how to connect. It also executes the commands and playbooks on the managed nodes.

B. Managed Nodes

Managed nodes are the servers, network devices, or other systems that are being managed by Ansible. These nodes are connected to and controlled by the control node, and they are the target of Ansible commands and playbooks. Managed nodes do not require any additional software to be installed, as Ansible uses SSH for communication.

Managed nodes are defined in the inventory file, which is located on the control node. The inventory file is a simple text file that lists the managed nodes, along with their IP addresses or hostnames, and any additional information that is needed to connect to them. This information is used by the control node to establish an SSH connection with each managed node and run the specified Ansible commands or playbooks.

Managed nodes can be grouped together in the inventory file, allowing Ansible commands and playbooks to be run against multiple nodes at once. For example, you could group all of the web servers together in a group called "web" and then run a playbook that updates the web servers' software against that group.

Managed nodes can be of different types, they can be servers, network devices, or any other type of device that can be managed via SSH or WinRM. Ansible can manage multiple platforms, including Linux, Windows, and network devices.

In summary, Managed nodes are the target of the Ansible automation, they are defined in the inventory file and grouped together, they can be of different types and platforms, and they don't require any additional software to be installed.

C. Ansible Modules

Ansible modules are small programs that are used to perform specific tasks on managed nodes. These tasks can include software installation, configuration changes, and service management. Ansible ships with a wide variety of built-in modules that can be used to perform common tasks on managed nodes, such as installing software, managing services, and modifying files.

Modules can be called from the command line using the ansible command, or they can be included in playbooks. Modules can be used to perform tasks such as:

Installing software

Managing services

Modifying files

Managing users and groups

Managing packages

Managing cron jobs

Managing system settings

Managing network settings

Managing cloud resources

Managing container

And many more.

Ansible also allows users to create custom modules, written in any programming language, to perform tasks that are not covered by the built-in modules. This allows for greater flexibility and customization in automation tasks.

In summary, Ansible modules are small programs that perform specific tasks on managed nodes, they can be used from the command line or included in playbooks, Ansible ships with a wide variety of built-in modules and also allows users to create custom modules to perform specific tasks that are not covered by the built-in modules.

D. Ansible Playbooks

Ansible playbooks are files that contain a series of tasks, written in the YAML language, that are executed on managed nodes. Playbooks are used to automate complex or multi-step tasks that involve multiple managed nodes. They are a powerful feature of Ansible that allow for the coordinated execution of tasks, and the ability to define variables and control flow.

A playbook is a list of one or more plays, and each play is a list of one or more tasks. Each task is a single Ansible module call, and it specifies the module to use and any arguments or options needed for that module.

Playbooks can be used to perform tasks such as:

Installing software

Configuring services

Deploying applications

Managing users and groups

Managing packages

Managing cron jobs

Managing system settings

Managing network settings

Managing cloud resources

Managing container

And many more.

Playbooks are executed on the control node, and they use the inventory file to determine which managed nodes to connect to. The control node connects to the managed nodes using SSH and runs the tasks specified in the playbook. The results of the playbook are returned to the control node and can be saved for later use or analysis.

In summary, Ansible playbooks are files that contain a series of tasks written in YAML, they are used to automate complex or multi-step tasks that involve multiple managed nodes, playbooks are executed on the control node and use the inventory file to determine which managed nodes to connect to, and the results of the playbook can be saved for later use or analysis.