Inventory

First PublishedFeb 16, 2026ByAtif Alam

The inventory tells Ansible which hosts to manage. It can be a simple text file, a YAML file, or a script that dynamically queries your cloud provider.

Static Inventory (INI Format)

The simplest form — a file listing hosts and groups:

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[webservers]
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web1.example.com
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web2.example.com
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192.168.1.50
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[dbservers]
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db1.example.com
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db2.example.com
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[loadbalancers]
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lb1.example.com

Run against this inventory:

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ansible -i inventory.ini webservers -m ping
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ansible-playbook -i inventory.ini site.yml

Static Inventory (YAML Format)

The same inventory in YAML:

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all:
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  children:
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    webservers:
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      hosts:
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        web1.example.com:
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        web2.example.com:
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        192.168.1.50:
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    dbservers:
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      hosts:
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        db1.example.com:
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        db2.example.com:
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    loadbalancers:
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      hosts:
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        lb1.example.com:

YAML format is more verbose but better for complex inventories with nested variables.

Groups

Every host belongs to at least two groups:

all — Every host in the inventory.
ungrouped — Hosts not in any other group.

Group of Groups (Children)

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[webservers]
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web1.example.com
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web2.example.com
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[dbservers]
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db1.example.com
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[production:children]
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webservers
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dbservers

Now production contains all hosts from webservers and dbservers.

YAML equivalent:

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all:
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  children:
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    production:
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      children:
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        webservers:
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          hosts:
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            web1.example.com:
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            web2.example.com:
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        dbservers:
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          hosts:
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            db1.example.com:

Host and Group Variables

Inline Variables (INI)

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[webservers]
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web1.example.com ansible_port=2222 http_port=8080
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web2.example.com http_port=80

Inline Variables (YAML)

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webservers:
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  hosts:
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    web1.example.com:
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      ansible_port: 2222
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      http_port: 8080
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    web2.example.com:
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      http_port: 80

Variable Files (Recommended)

For cleaner organization, use host_vars/ and group_vars/ directories:

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inventory/
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  hosts.yml
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  group_vars/
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    all.yml           # variables for all hosts
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    webservers.yml    # variables for webservers group
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    dbservers.yml     # variables for dbservers group
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  host_vars/
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    web1.example.com.yml   # variables for this specific host

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http_port: 80
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app_env: production
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deploy_user: deploy

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ansible_port: 2222
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http_port: 8080

Connection Variables

Special variables that control how Ansible connects:

Variable	Default	Purpose
`ansible_host`	inventory hostname	IP or hostname to connect to
`ansible_port`	22	SSH port
`ansible_user`	current user	SSH username
`ansible_ssh_private_key_file`	—	Path to SSH key
`ansible_become`	false	Enable privilege escalation (sudo)
`ansible_become_method`	sudo	How to escalate (`sudo`, `su`, `doas`)
`ansible_python_interpreter`	/usr/bin/python3	Python path on the remote host

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[webservers]
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web1.example.com ansible_user=deploy ansible_become=true

Patterns (Targeting Hosts)

Patterns let you target specific hosts or groups:

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ansible webservers -m ping            # all hosts in webservers
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ansible dbservers -m ping             # all hosts in dbservers
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ansible all -m ping                   # every host
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ansible web1.example.com -m ping      # single host
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ansible 'webservers:dbservers' -m ping  # union (both groups)
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ansible 'webservers:&production' -m ping  # intersection
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ansible 'webservers:!web1.example.com' -m ping  # exclude a host
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ansible '*.example.com' -m ping       # wildcard

The same patterns work in playbooks:

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- hosts: webservers:&production
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  tasks:
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    - name: Deploy app
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      # ...

Dynamic Inventory

Instead of a static file, a script or plugin queries your infrastructure and returns host lists in JSON.

AWS Example (aws_ec2 Plugin)

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plugin: amazon.aws.aws_ec2
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regions:
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  - us-east-1
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filters:
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  tag:Environment: production
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keyed_groups:
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  - key: tags.Role
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    prefix: role
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  - key: placement.availability_zone
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    prefix: az
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compose:
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  ansible_host: public_ip_address

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ansible-inventory -i inventory/aws_ec2.yml --graph    # see discovered hosts
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ansible -i inventory/aws_ec2.yml role_webserver -m ping

Other Dynamic Inventory Plugins

azure.azcollection.azure_rm — Azure VMs
google.cloud.gcp_compute — GCP instances
kubernetes.core.k8s — Kubernetes pods
community.docker.docker_containers — Docker containers

Default Inventory

Set a default inventory in ansible.cfg so you don’t need -i every time:

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# ansible.cfg
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[defaults]
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inventory = ./inventory/hosts.yml

Key Takeaways

Inventory defines what Ansible manages — hosts, groups, and their variables.
Use group_vars/ and host_vars/ directories for clean variable management.
Patterns let you target flexible subsets of hosts (webservers:&production, all:!staging).
Use dynamic inventory plugins for cloud environments — hosts are discovered automatically.
Set a default inventory in ansible.cfg to avoid passing -i on every command.