{"id":51385,"date":"2025-08-07T06:23:32","date_gmt":"2025-08-07T06:23:32","guid":{"rendered":"https:\/\/www.devopsschool.com\/blog\/?p=51385"},"modified":"2025-08-07T06:23:37","modified_gmt":"2025-08-07T06:23:37","slug":"ansible-all-ways-to-define-variables-in-ansible-inventory-hosts","status":"publish","type":"post","link":"https:\/\/www.devopsschool.com\/blog\/ansible-all-ways-to-define-variables-in-ansible-inventory-hosts\/","title":{"rendered":"Ansible: All Ways to Define Variables in Ansible Inventory\/Hosts"},"content":{"rendered":"\n

Here\u2019s a comprehensive tutorial on all the ways to define and use variables in Ansible inventory\/hosts<\/strong>, covering every major approach\u2014including their best use cases and clear examples<\/strong> for each.<\/p>\n\n\n\n

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Complete Guide: All Ways to Define Variables in Ansible Inventory\/Hosts<\/strong><\/h1>\n\n\n\n

Ansible variables make playbooks and roles flexible and dynamic. Variables can be defined in multiple ways, with different precedence and scopes: per host, per group, globally, in YAML, in INI, or in directory structures.<\/p>\n\n\n\n

Below, we\u2019ll cover every method<\/strong> with examples<\/strong>.<\/p>\n\n\n\n

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1. Host Variables in Inventory File (Host Vars)<\/strong><\/h2>\n\n\n\n

Define variables directly for a single host in the INI inventory file:<\/p>\n\n\n

[webservers]\nweb1 ansible_host=192.168.1.101 http_port=80 max_clients=200\nweb2 ansible_host=192.168.1.102 http_port=8080 max_clients=150\n<\/code><\/span><\/pre>\n\n\n
Usage in playbook\/task:<\/strong><\/p>\n\n\n
- name: Show host vars\n  hosts<\/span>: webservers\n  tasks<\/span>:\n    - debug: msg=\"Host {{ inventory_hostname }} uses port {{ http_port }} and max clients {{ max_clients }}\"<\/span>\n<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\n
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2. Group Variables in Inventory File (Group Vars)<\/strong><\/h2>\n\n\n\n
Define variables for all hosts in a group in the INI inventory:<\/p>\n\n\n
[dbservers]\ndb1 ansible_host=192.168.1.201\ndb2 ansible_host=192.168.1.202<\/code><\/span><\/pre>\n\n
[dbservers:vars]<\/p>\n\n\n\n
db_port=3306 backup_window=02:00<\/p>\n\n\n\n
All hosts in [dbservers]<\/code> get db_port<\/code> and backup_window<\/code>.<\/p>\n\n\n\n
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3. Global (All) Group Vars<\/strong><\/h2>\n\n\n\n
Set variables for all hosts by using the [all:vars]<\/code> section in your INI inventory:<\/p>\n\n\n
[all:vars]\nenv=production\nadmin_email=admin@example.com\n<\/code><\/span><\/pre>\n\n\n
All hosts will inherit these.<\/p>\n\n\n\n
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4. Using YAML Inventory (hosts.yml<\/code>)<\/strong><\/h2>\n\n\n\n
YAML-style inventory files let you define hosts, groups, and variables in a structured way:<\/p>\n\n\n
all<\/span>:\n  vars<\/span>:\n    datacenter<\/span>: DC1<\/span>\n  children<\/span>:\n    webservers<\/span>:\n      hosts<\/span>:\n        web1<\/span>:\n          ansible_host<\/span>: 192.168<\/span>.1<\/span>.101<\/span>\n          http_port<\/span>: 80\n        web2<\/span>:\n          ansible_host<\/span>: 192.168<\/span>.1<\/span>.102<\/span>\n          http_port<\/span>: 8080\n      vars<\/span>:\n        nginx_version<\/span>: 1.24<\/span>\n    dbservers<\/span>:\n      hosts<\/span>:\n        db1<\/span>:\n        db2<\/span>:\n      vars<\/span>:\n        db_port<\/span>: 3306\n<\/code><\/span>Code language:<\/span> CSS<\/span> (<\/span>css<\/span>)<\/span><\/small><\/pre>\n\n\n
Usage in playbook:<\/strong> Variables are accessed as usual ({{ db_port }}<\/code> etc).<\/p>\n\n\n\n
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5. Host and Group Variable Files (host_vars<\/code> & group_vars<\/code> Directory)<\/strong><\/h2>\n\n\n\n
This is the most powerful and recommended way for larger projects<\/strong>.<\/p>\n\n\n\n
Directory structure:<\/strong><\/p>\n\n\n
inventory\/\n  hosts        # inventory file (can be INI or YAML)<\/span>\n  group_vars\/\n    all.yml    # applies to all hosts<\/span>\n    webservers.yml\n    dbservers.yml\n  host_vars\/\n    web1.yml\n    db1.yml\n<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Example:<\/strong><\/p>\n\n\n\n