Introduction to Ansible
Ansible is a software tool that enables cross-platform automation and orchestration at scale and has become over the years the standard choice among enterprise automation solutions.
It’s mostly addressed to IT operators, administrators, and decision-makers, helping them achieve operational excellence across their entire infrastructure ecosystem.
Backed by RedHat and a loyal open source community, it is considered an excellent option for configuration management, infrastructure provisioning, and application deployment use cases.
Workflow
Ansible uses the concepts of control and managed nodes. It connects from the control node, any machine with Ansible installed, to the managed nodes sending commands and instructions to them.
The units of code that Ansible executes on the managed nodes are called modules. Each module is invoked by a task, and an ordered list of tasks together forms a playbook. Users write playbooks with tasks and modules to define the desired state of the system.
The managed machines are represented in a simplistic inventory file that groups all the nodes into different categories.
Ansible leverages a very simple language, YAML, to define playbooks in a human-readable data format that is really easy to understand from day one.
Use Cases of Ansible
Automation(Any system automation, Server, Database, configuration, start restart services)
Change Management (Production server changes)
Provisionning(Setup server from scratch or cloud provisioning)
Orchestration(Large scale automation framework, can integrate with other tool like jenkins, docker)
Basic Concepts & Terms
Host: A remote machine managed by Ansible.
Group: Several hosts grouped together that share a common attribute.
Inventory: A collection of all the hosts and groups that Ansible manages. Could be a static file in the simple cases or we can pull the inventory from remote sources, such as cloud providers.
Modules: Units of code that Ansible sends to the remote nodes for execution.
Tasks: Units of action that combine a module and its arguments along with some other parameters.
Playbooks: An ordered list of tasks along with its necessary parameters that define a recipe to configure a system.
Roles: Redistributable units of organization that allow users to share automation code easier.
YAML: A popular and simple data format that is very clean and understandable by humans.
Ansible Config File
This file named ansible.cfg it contains important configurations.
Default location for this file is /etc/ansible/ansible.cfg.
[defaults]
inventory = ./inventory
host_key_checking = FalseOrder of Ansible Config
ANSIBLE_CONFIG (set environment variable)
ansible.cfg (in the current directory)
~/.ansible.cfg (in the home directory)
/etc/ansible/ansible.cfg
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