An inventory file is a simple and plain text file where we store those host information ansible has to deal with. It can be simple in any format (YAML, ini, etc). Default inventory file location is /etc/ansible/hosts but you can specify a different inventory file in your ansible config file (as above) or using the -i option on the command line.
[[email protected] ~]# ansible all -m ping -i myinventory
Here see a sample inventory file.
[myself]
localhost
[intranetweb]
servera.techbeatly.com
serverb.techbeatly.com
[database]
db101.techbeatly.com
[everyone:children]
myself
intranetweb
database
You can see, this is a simple one in ini format and contains few hosts and groups. Group myself contains only one host which is localhost. (Not a mandatory one, I have given as an example). intranetweb group containers 2 servers – servera.techbeatly.com and serverb.techbeatly.com. db101.techbeatly.com is under database group. And finally we have group everyone with all other groups as children.
Lets check what ansible can understand from this inventory file.
[[email protected] ansible]# ansible all --list-hosts
hosts (4):
db101.techbeatly.com
localhost
servera.techbeatly.com
serverb.techbeatly.com
[[email protected] ansible]# ansible intranetweb --list-hosts
hosts (2):
servera.techbeatly.com
serverb.techbeatly.com
Here see some of the sample ansible --list-host
pattern for reference.
ansible db1.example.com -i inventory --list-hosts
ansible -i inventory --list-hosts 172.25.252.44
ansible -i inventory --list-hosts all
ansible -i inventory --list-hosts london
ansible -i inventory --list-hosts environments
ansible -i inventory --list-hosts ungrouped
ansible -i inventory --list-hosts '.example.com'
ansible -i inventory --list-hosts '.example.com,!.lab.example.com'
ansible -i inventory --list-hosts lb1.lab.example.com,s1.lab.example.com,db1.example.com
ansible -i inventory --list-hosts '172.25.'
ansible -i inventory --list-hosts 's'
ansible -i inventory --list-hosts 'prod,172,lab'
ansible -i inventory --list-hosts 'db,&london'
If you are adding a lot of hosts following similar patterns, you can add as below rather than listing each hostname:
[webservers]
www[01:50].example.com
[databases]
db-[a:f].example.com
192.168.0.[10:20]
[a:c].dns.example.com
Inventory can be static (like ini or YAML format) or dynamic via inventory scripts. For those working on cloud or container based environment, you will not be able to manage inventory with a static source. In that case you need a dynamic inventory system with scripts.
There are few sample inventory scripts available by community; check this repo for samples. Also read Working with Dynamic Inventories.
[[email protected] dep-dynamic]$ inventory/myinventory.py --list
{"webservers": {"hosts": ["servera.teachbeatly.com"], "vars": {}}}
Let’s learn about ad-hoc commands in next chapter.
See all parts of Automation with Ansible Guides here
Disclaimer: The views expressed and the content shared are those of the author and do not reflect the views of the author’s employer or techbeatly platform.
Tags: Ansible · ansible command · Ansible Doc · ansible inventory · ansible training · Automation
Gineesh Madapparambath
Gineesh Madapparambath is the founder of techbeatly and he is the author of the book - ๐๐ป๐๐ถ๐ฏ๐น๐ฒ ๐ณ๐ผ๐ฟ ๐ฅ๐ฒ๐ฎ๐น-๐๐ถ๐ณ๐ฒ ๐๐๐๐ผ๐บ๐ฎ๐๐ถ๐ผ๐ป.
He has worked as a Systems Engineer, Automation Specialist, and content author. His primary focus is on Ansible Automation, Containerisation (OpenShift & Kubernetes), and Infrastructure as Code (Terraform).
(aka Gini Gangadharan - iamgini.com)
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