DevOps Classroom notes 11/Nov/2026

Ansbile Inventory

• Inventory is list of machines (hosts)
• /etc/ansible/hots default Inventory path

An Inventory can defined

1. hosts: Individual severs

10.10.1.0
10.20.2.0

2. groups: collections of hosts (webservers and dbservers)

[dev]
10.0.1.0
10.0.2.0
10.0.3.0
10.0.4.0

[webservers]
10.2.1.0
10.3.2.0
10.4.3.0
10.56.4.0

3. variables: setting attachment for hosts or groups (port, users, password, app version …etc)
4. nested Groups: groups of groups

[production]
backend
webservers

[backend]
10.0.1.0
10.0.2.0
10.0.3.0
10.0.4.0

[webservers]
10.2.1.0
10.3.2.0
10.4.3.0
10.56.4.0

Validate connection ansible all -i Inventory_file -m ping

Types of Inventory

1. Static inventory:

• a fixed file (INI or yaml ) that can be edit by you
• best for small and stable enviroment onprem

2. Dynamic inventory

• could api to fetch nodes ip address (run scrpit and generate inventory file)
• best for cloud and autoscalling enviroment

3. Inventory Directory

• A Directory conatianing multiple files/scrpits combine together (both Static and Dynamic)
• best for cloud and on-prem mixed enviroments

4. INLINE/ ad-hoc inventory

• host pass Directly from cmd line
• best for Quick test

Static Inventory:

• plan text add all hosts and groups

Ex: INI format

backend-api.ini.com

10.55.55.6 anasible_user=ansible ansible_password=ansible@123 

[backend]
10.0.1.0
10.0.2.0 ansible_port=23
10.0.3.0 ansible_pasword=ansible@123
10.0.4.0

[webservers]
10.2.1.0
10.3.2.0
10.4.3.0
10.56.4.0

[webservers:vars]
anasible_user=ubuntu
ansible_password=ansible@123


[all:vars]
ansible_port=22

same in yaml format

all:
  vars:
    ansible_port: 22

  hosts:
    backend-api.ini.com:
      ansible_host: 10.55.55.6
      ansible_user: ansible
      ansible_password: "ansible@123"

  children:
    backend:
      hosts:
        10.0.1.0:
        10.0.2.0:
          ansible_port: 23
        10.0.3.0:
          ansible_password: "ansible@123"
        10.0.4.0:

    webservers:
      hosts:
        10.2.1.0:
        10.3.2.0:
        10.4.3.0:
        10.56.4.0:

      vars:
        ansible_user: ubuntu
        ansible_password: "ansible@123"

Host range patter

[webservers]
web[01:50].amazon.in # web01-web50

web01.amazon.in
web02.amazon.in
web03.amazon.in
...
web50.amazon.in


[dbservers]
10.0.20.[05:155] # 10.0.20.05 --> 10.0.20.155

10.0.20.05
10.0.20.06
10.0.20.07
10.0.20.155

Common Inventory (Connection) Variables

Variable	Purpose	Example
ansible_host	Real IP/DNS to connect to (alias differs from address)	ansible_host=10.0.1.15
ansible_port	SSH port	ansible_port=2222
ansible_user	Remote login user	ansible_user=ubuntu
ansible_password	SSH password (prefer Vault)	ansible_password=secret
ansible_ssh_private_key_file	SSH key path	~/.ssh/id_rsa
ansible_connection	Connection type	ssh, local, winrm, docker
ansible_become	Use privilege escalation	true
ansible_become_user	User to become	root
ansible_python_interpreter	Python path on the target	/usr/bin/python3

Offical docs connection varibales

Task:

1. create Static inventory and validate above methods like host, groups, all, variables…etc