How to define variables in Ansible?

In Ansible, you can define variables in several ways. Here are the most common methods:

In the Playbook: You can define variables directly within your playbook using the vars section.

- hosts: all
  vars:
    http_port: 80
    db_port: 3306
  tasks:
    - name: Print HTTP port
      debug:
        msg: "HTTP port is {{ http_port }}"

In Inventory Files: You can define host or group variables in your inventory file.
```
[web]
localhost http_port=80

[db]
localhost db_port=3306
```
In Variable Files: You can create separate YAML files to store variables and include them in your playbook. For example, create a file named vars.yml:
```
http_port: 80
db_port: 3306
```
Then include it in your playbook:
```
- hosts: all
  vars_files:
    - vars.yml
  tasks:
    - name: Print HTTP port
      debug:
        msg: "HTTP port is {{ http_port }}"
```
As Facts: Ansible automatically gathers facts about the managed nodes, which can be used as variables. You can access these facts using the ansible_facts variable.
```
- hosts: all
  tasks:
    - name: Print OS version
      debug:
        msg: "Operating System is {{ ansible_facts['os'] }}"
```
Using Command Line: You can also pass variables at runtime using the -e option with the ansible-playbook command.
```
ansible-playbook my-playbook.yml -e "http_port=80 db_port=3306"
```

These methods allow you to define and manage variables effectively in your Ansible automation tasks.