Ansible Magic Variables - Ansible Tip and Tricks

How to Ansible Internal Variables “Magic” could simplify our automation journey: running Ansible version, inventory details, and execution options

May 30, 2022

How to Use Ansible Magic Variables in Ansible Playbook

I’m going to show you a live demo and some simple Ansible code. I’m Luca Berton and welcome to today’s episode of Ansible Pilot.

Ansible Magic Variables

How to Ansible Magic Variables in Ansible Playbook. The good news is that Ansible provides some internal variables that come out of the box with some information such as running the Ansible version, inventory details, or execution options. Some examples:

• playbook_dir

The path to the directory of the playbook that was passed to the ansible-playbook command line

• inventory_dir

The directory of the inventory source in which the inventory_hostname was first defined

• inventory_file

The file name of the inventory source in which the inventory_hostname was first defined

• inventory_hostname

The inventory name for the ‘current’ host is being iterated over in the play

• ansible_check_mode / ansible_diff_mode

Boolean that indicates if we are in check/diff mode or not

• ansible_version

Dictionary/map that contains information about the currently running version of ansible, it has the following keys: full, major, minor, revision and string.

Links

The full list is available on the official Ansible website Magic variables

The Best Resources For Ansible

Video Course

• Learn Ansible Automation in 250+examples & practical lessons: Learn Ansible with some real-life examples of how to use the most common modules and Ansible Playbook

Printed Book

• Ansible For VMware by Examples: A Step-by-Step Guide to Automating Your VMware Infrastructure

eBooks

• Ansible by Examples: 200+ Automation Examples For Linux and Windows System Administrator and DevOps
• Ansible For Windows By Examples: 50+ Automation Examples For Windows System Administrator And DevOps
• Ansible For Linux by Examples: 100+ Automation Examples For Linux System Administrator and DevOps
• Ansible Linux Filesystem By Examples: 40+ Automation Examples on Linux File and Directory Operation for Modern IT Infrastructure
• Ansible For Containers and Kubernetes By Examples: 20+ Automation Examples To Automate Containers, Kubernetes and OpenShift
• Ansible For Security by Examples: 100+ Automation Examples to Automate Security and Verify Compliance for IT Modern Infrastructure
• Ansible Tips and Tricks: 10+ Ansible Examples to Save Time and Automate More Tasks
• Ansible Linux Users & Groups By Examples: 20+ Automation Examples on Linux Users and Groups Operation for Modern IT Infrastructure
• Ansible For PostgreSQL by Examples: 10+ Examples To Automate Your PostgreSQL database
• Ansible For Amazon Web Services AWS By Examples: 10+ Examples To Automate Your AWS Modern Infrastructure

demo

How to use Ansible Magic Variables in Ansible Playbook? Let’s see in action some of the most common Ansible Magic Variables in an Ansible Playbook. I’m going to display the current value of the following variables:

• ansible_config_file

The full path of the used Ansible configuration file playbook_dir

The path to the directory of the playbook was passed to the ansible-playbook command line.

• inventory_dir

The directory of the inventory source in which the inventory_hostname was first defined

• inventory_file

The file name of the inventory source in which the inventory_hostname was first defined

• ansible_check_mode

Boolean that indicates if we are in check mode or not

• ansible_diff_mode

Boolean that indicates if we are in diff mode or not

• ansible_forks

Integer reflecting the number of maximum forks available to this run

• ansible_verbosity

Current verbosity setting for Ansible

• inventory_hostname

The inventory name for the ‘current’ host is being iterated over in the play

• ansible_play_hosts

List of hosts in the current play run, not limited by the serial. Failed/Unreachable hosts are excluded from this list.

• ansible_version

Dictionary/map that contains information about the currently running version of ansible, it has the following keys: full, major, minor, revision and string.

code

---
- name: magic vars demo
  hosts: all
  gather_facts: false
  tasks:
    - name: magic variable
      ansible.builtin.debug:
        var: "{{ item }}"
      loop:
        - ansible_config_file
        - playbook_dir
        - inventory_dir
        - inventory_file
        - ansible_check_mode
        - ansible_diff_mode
        - ansible_forks
        - ansible_verbosity
        - inventory_hostname
        - ansible_play_hosts
        - ansible_version

execution

$ ansible-playbook -i virtualmachines/demo/inventory variables/magic.yml
PLAY [magic vars demo] ****************************************************************************
TASK [magic variable] *****************************************************************************
ok: [demo.example.com] => (item=ansible_config_file) => {
    "ansible_config_file": null,
    "ansible_loop_var": "item",
    "item": "ansible_config_file"
}
ok: [demo.example.com] => (item=playbook_dir) => {
    "ansible_loop_var": "item",
    "item": "playbook_dir",
    "playbook_dir": "/Users/lberton/prj/github/ansible-pilot/variables"
}
ok: [demo.example.com] => (item=inventory_dir) => {
    "ansible_loop_var": "item",
    "inventory_dir": "/Users/lberton/prj/github/ansible-pilot/virtualmachines/demo",
    "item": "inventory_dir"
}
ok: [demo.example.com] => (item=inventory_file) => {
    "ansible_loop_var": "item",
    "inventory_file": "/Users/lberton/prj/github/ansible-pilot/virtualmachines/demo/inventory",
    "item": "inventory_file"
}
ok: [demo.example.com] => (item=ansible_check_mode) => {
    "ansible_check_mode": false,
    "ansible_loop_var": "item",
    "item": "ansible_check_mode"
}
ok: [demo.example.com] => (item=ansible_diff_mode) => {
    "ansible_diff_mode": false,
    "ansible_loop_var": "item",
    "item": "ansible_diff_mode"
}
ok: [demo.example.com] => (item=ansible_forks) => {
    "ansible_forks": 5,
    "ansible_loop_var": "item",
    "item": "ansible_forks"
}
ok: [demo.example.com] => (item=ansible_verbosity) => {
    "ansible_loop_var": "item",
    "ansible_verbosity": 0,
    "item": "ansible_verbosity"
}
ok: [demo.example.com] => (item=inventory_hostname) => {
    "ansible_loop_var": "item",
    "inventory_hostname": "demo.example.com",
    "item": "inventory_hostname"
}
ok: [demo.example.com] => (item=ansible_play_hosts) => {
    "ansible_loop_var": "item",
    "ansible_play_hosts": [
        "demo.example.com"
    ],
    "item": "ansible_play_hosts"
}
ok: [demo.example.com] => (item=ansible_version) => {
    "ansible_loop_var": "item",
    "ansible_version": {
        "full": "2.12.5",
        "major": 2,
        "minor": 12,
        "revision": 5,
        "string": "2.12.5"
    },
    "item": "ansible_version"
}
PLAY RECAP ****************************************************************************************
demo.example.com           : ok=1    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

Recap

Now you know how to use the Ansible Magic Variables in Ansible Playbook. You know how to use it based on your use case.

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