Ansible - Variables 🔡

Description 👀

Variables store information that varies with each host. Variables can be used to store information about a host, such as its IP address, hostname, or operating system.

Variables can also be used to store information about a group of hosts, such as the name of a database server or the name of a web server.

To use a variable, you must enclose the variable name in double curly braces

• i.e

Basics 📝

• inventory variables

    # inventory.txt
    [<group-name>]
    <host>
  
    [<group-name>:vars]
    <variableX>=<valueY>
  

• playbook variables

    # playbook.yml
    - name: <play name> 
      hosts: <host-pattern>
      # variables are stored under the `vars` key using the `key: value` format
      vars:
        <variableX>: <valueY>
      tasks:
        - <module>:
            <key>: <value>
  

• separate variables file

    # vars.yml
    <variableX>: <valueY>
  

  • variable files named after hosts/groups allows ansible to load the variables when the host/group is referenced

Examples 🧩

• inventory variables

    # inventory.txt
    [web]
    host1.example.com
    host2.example.com
  
    [web:vars]
    http_port=80
    maxRequestsPerChild=8080
  

  • host1.example.com and host2.example.com are both members of the web group
  • http_port and maxRequestsPerChild are variables that are defined for the web group

• playbook variables

    # playbook.yml
    - name: Add a DNS server to /etc/resolv.conf 
      hosts: localhost
      # variables are stored under the `vars` key using the `key: value` format
      vars:
        dns_server: 10.1.250.10
      tasks:
        - lineinfile: 
            path: /etc/resolv.conf
            line: 'nameserver '
  

• separate variables file

    # vars.yml
    variable1: value1
    variable2: value2
  

• playbook using variables in variables file

    # inventory.txt
    [web]
    host1.example.com
    host2.example.com
  

    # web.yml
    # can be used whenever the host is part of the `web` group
    http_port: 80
    snmp_port: 161-162
    inter_ip_range: 192.0.2.0
  

    # playbook.yml
    -
      name: Set Firewall Configuration
      hosts: web
      tasks:
  
        - firewalld:
            service: https
            permanent: true
            state: enabled
  
        - firewalld:
            port: "/tcp"
            permanent: true
            state: disabled
  
        - firewalld:
            port: "/udp"
            permanent: true
            state: enabled
  
        - firewalld:
            source: "/24"
            Zone: internal
            state: enabled
  

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