Introduction to Ansible

Ansible is an open-source automation tool developed by Red Hat for:

• • Configuration Management
• • Application Deployment
• • Automated Task Execution
• • Batch Operations on Multiple Servers

Its main features are: Agentless + SSH-based connection + YAML scripting (high readability).

Why Choose Ansible?

Feature	Description
✅ Agentless	No agent installation required on managed nodes, operations are performed directly via SSH
✅ Easy to Learn	Playbooks are written in YAML, which is highly readable
✅ Rich Modules	Built-in and community modules support various platforms and tasks
✅ Cross-Platform	Manages Linux, Windows, network devices, etc.
✅ Extensible	Supports custom modules and a plugin system
✅ Active Community	Rich open-source resources and documentation available

What Can Ansible Do?

• • Batch deployment of software (e.g., installing nginx, mysql)
• • Configuration file distribution and template replacement
• • Restarting services, managing users, configuring firewalls, etc.
• • Automated deployment of web applications, containers, cloud services (AWS, Azure)
• • Orchestrating cross-host tasks (e.g., deploying Hadoop, K8s, Ceph)

Ansible Architecture

The Ansible control node is responsible for issuing tasks and includes the following components:

• • Ansible: Ansible-core, the main program of Ansible, includes related binaries
• • Inventory: A list of hosts used to define the managed servers
• • Ad Hoc: Ansible’s command line for executing simple tasks or debugging
• • Playbooks: Scripts used to define complex automation tasks
• • Core Modules: The essential modules of Ansible, which include the most commonly used modules (prior to Ansible 2.10, many modules were included, but only a few core modules are included after 2.10)
• • Ansible Collections: Core modules only meet basic functionality; new modules can be installed via Ansible Collections to extend Ansible’s capabilities
• • Connection Plugins: Connection plugins define how Ansible connects to remote hosts

The process of managing hosts with Ansible:

1. 1. Ansible defines the host list through Inventory
2. 2. Tasks are defined through Playbooks or Ad Hoc (tasks are executed via modules) and the hosts on which tasks will be executed
3. 3. Modules are pushed to the managed nodes via connection plugins
4. 4. Tasks are executed on the managed nodes, and the modules are deleted after execution

Most of Ansible’s modules are idempotent, meaning that executing them multiple times will only modify what needs to be changed. However, some modules, such as <span>raw</span>, <span>command</span>, and <span>shell</span> modules, are exceptions.

The Ansible control node must be a Linux system.

Devices and Connection Methods Managed by Ansible:

Device Type	Default Connection Method	Description
Linux Systems	SSH	The most common method, supports passwordless or key-based login
Windows Systems	WinRM	Requires configuration of the WinRM service, supports HTTP/HTTPS
Network Devices	SSH or API	Uses specific modules/collections; some devices require NETCONF
Cloud Platforms	API (HTTPS)	Utilizes SDK/REST API, requires Access Key, Token, etc.
Kubernetes / OpenShift	API Server	Connects to kube-apiserver using kubeconfig or Token
Docker / Podman	Local or Remote API	Connects via Unix socket or remote TCP port
Storage/Virtualization Devices	API or SSH	e.g., VMware uses vCenter API, Dell EMC uses REST API
HTTP Services	URI Module	<span>ansible.builtin.uri</span> can call REST interfaces
Custom Services	Command/Script/API	Can use <span>command</span>, <span>shell</span>, or <span>script</span> modules to invoke

Ansible uses the available connection methods of the managed nodes to manage them, such as managing Linux via SSH, which is why Ansible is agentless and does not require an agent to be installed on the managed nodes.