NetworkPuzzles

When automating network devices with Ansible, collecting device information (facts) is usually the first step.

In this lab, we will:

• Configure Ansible
• Define an inventory file
• Use cisco.ios.ios_facts
• Save the output to a JSON file
• Print selected device information

Ansible Configuration (ansible.cfg)

[defaults]
host_key_checking = false    #Disables SSH fingerprint verification
inventory = invt.yaml  #Tells Ansible which inventory file to use by default.
gathering = explicit   #Ansible will only gather facts if we explicitly request it

Inventory File (invt.yaml)

all:
  vars:
    ansible_user: admin
    ansible_password: cisco
    ansible_network_os: ios
    ansible_connection: network_cli

  children:
    routers:
      hosts:
        R1:
          ansible_host: 192.168.199.30
        R2:
          ansible_host: 192.168.199.31

We created a group called routers.

This allows us to target:

• One device → hosts: R1
• All routers → hosts: routers

Playbook – Gathering Facts

---
- name: "Gathering Facts"
  hosts: R1
  tasks:

    - name: Gather all Facts
      cisco.ios.ios_facts:
        gather_subset: interfaces
      register: cli_result

    - name: "Saving facts into output.json file"
      copy:
        content: "{{ cli_result | to_nice_json }}"
        dest: output.json

    - name: "Printing version"
      debug:
        msg: "{{ cli_result.ansible_facts.ansible_net_hostname }} >>> {{ cli_result.ansible_facts.ansible_net_version }}"

    - name: "Printing Facts"
      debug:
        msg: "{{ cli_result }}"

Let see each section separately:

Task 1 – Gather Facts

cisco.ios.ios_facts:
  gather_subset: interfaces

This module:

• Connects via SSH
• Runs internal commands
• Parses structured data
• Returns device facts

gather_subset: interfaces means:
We only collect interface-related information.

Other useful subsets:

• interface
• config
• all

The result is stored using: register: cli_result

Task 2 – Save Output to JSON

content: "{{ cli_result | to_nice_json }}"
dest: output.json

This:

• Converts the Python dictionary into formatted JSON
• Saves it locally

This is extremely useful for:

• Troubleshooting
• Documentation
• Feeding data into other automation tools

Task 3 – Print Device Version

msg: "{{ cli_result.ansible_facts.ansible_net_hostname }} >>> {{ cli_result.ansible_facts.ansible_net_version }}"

This task will find the ansible_net_version which is under ansible_facts under cli_result.ansible and print it in front of the host name. If we want to pars some special info we can find where is it in the hierarchical out put of gather facts all then point directly to that specific data.

Also the detain info about the modules are in available ansible official documentation: for this example:
https://docs.ansible.com/projects/ansible/latest/collections/cisco/ios/ios_facts_module.html#ansible-collections-cisco-ios-ios-facts-module