Ansible_inventory Parameters

 Inventory Parameters

inventory is called as collection of hosts

inventory parameters are variables or settings you define in your inventory file to control how hosts and groups behave during playbook execution.

ansible_host # Hostname or IP address to SSH to

ansible_port # Port to SSH to

ansible_user # User to SSH as

ansible_password # Password to use for SSH authentication

ansible_ssh_private_key_file # SSH private key to use for SSH authentication

ansible_become=true

ansible_become_user=root

ansible_become_method=sudo(or)su

localhost ansible_connection=local

Custom variable

web1 app_port=8080 env=prod

ansible_connection

Ansible supports multiple transports to connect hosts

The default transport, smart

Ansible will check whether the locally installed SSH client supports a feature called ControlPersist. If the SSH client supports ControlPersist, Ansible will use the local SSH client.

If not, the smart transport will fall back to using a Python-based SSH client library called Paramiko.

ansible_shell_type

Ansible works by making SSH connections to remote machines and then invoking scripts. By default, Ansible assumes that the remote shell is the Bourne shell located at /bin/sh, and will generate the appropriate command-line parameters that work with that. It creates temporary directories to store these scripts.

Ansible also accepts csh, fish, and (on Windows) powershell as valid values for this parameter. Ansible doesn’t work with restricted shells.

ansible_python_interpreter

Ansible needs to know the location of the Python interpreter on the remote machine

ansible_python_interpreter="/usr/bin/env python3"

ansible_*_interpreter

If you are using a custom module that is not written in Python, you can use this parameter to specify the location of the interpreter

eg

[web]

web1 ansible_host=192.168.1.10 ansible_user=ec2-user ansible_port=22

[web]

web1

web2

[web:vars]

ansible_user=ec2-user

ansible_ssh_private_key_file=/home/user/key.pem

eg

web1 app_port=8080 env=prod

Pattern Matching Inventory

$ ansible web -m ping

$ ansible 'web:&prod' -m ping

$ ansible 'web:!db' -m ping

Operators

: → OR

& → AND

! → NOT

$ ansible-inventory --list

$ ansible-inventory --graph

Ansible automatically defines a group called all (or *)

$ ansible all -a "date"

or

$ ansible '*' -a "date"

Bill Baker of Microsoft came up with the distinction between treating servers as pets versus treating them like cattle.

The “cattle” approach to servers is much more scalable

20 servers are named web1.example.com, web2.example.com ... and so on

[web]

web[1:20].example.com

web-a.example.com, web-b.example.com, and so on....

[web]

web-[a:t].example.com

Ansible will let you add hosts and groups to the inventory during the execution of a playbook.

Adding Entries at Runtime with add_host and group_by

This is useful when managing dynamic clusters, such as Redis Sentinel.

add_host

The add_host module adds a host to the inventory; this is useful if you’re using Ansible to provision new virtual machine instances

- name: Add the host

add_host

name: hostname

groups: web,staging

myvar: myval

group_by

Ansible’s group_by module allows you to create new groups while a playbook is executing.

Any group you create will be based on the value of a variable that has been set on each host, which Ansible refers to as a fact.

- name: Create groups based on Linux distribution

group_by:

key: "{{ ansible_facts.distribution }}"