NetworkPuzzles

In this post, I’ll walk through several small but powerful Ansible playbook examples.
Each example focuses on a specific concept such as variables, loops, conditions, filters, lookups, and facts.

These are small puzzle pieces — but together they form the foundation of automation.

Variables in a Playbook + Filters

It defines a variable directly inside the playbook and prints it using the debug module.
It also demonstrates how to use a filter (type_debug) to see the variable type.

• vars: → define variables in the playbook
• {{ variable }} → reference variables
• | filter → apply Jinja2 filters

msg: "The IP is: {{ IP_Addr | type_debug }}"

This helps when troubleshooting type mismatches in complex automation workflows.

Using shell + register + Parsing Output

It executes a shell command (ping), Saves the output using register and Parses and manipulates the output.

• shell: → run local shell command
• register: → store task output
• output.stdout → access dictionary key
• .split('\n') → convert output to list

msg: "{{ output.stdout.split('\n') }}"

This converts command output into a list, making it easier to loop over lines later.

In network automation, this is often used before parsing CLI output into structured data.

Using vars_prompt (Interactive Input)

It prompts the user for input during playbook execution.

• vars_prompt
• private: no → show input
• encrypt: sha512_crypt
• confirm: yes

Working with Lists

It defines a list and accesses its elements.

• Lists in YAML
• Indexing like Python (IP_Addr[1])

Without specifying an index → entire list is printed
With index → specific element is printed

Working with Dictionaries

It defines key-value pairs and retrieves values using keys.

IP_Addr['R1']

devices:
  R1: 192.168.199.30
  R2: 192.168.199.31

Using when Conditions

It executes a task only if a condition is met.

when: ansible_facts['os_family'] == "Debian"

when:
  - ansible_facts['os_family'] == "Debian"
  - ansible_facts['distribution_version'] | int >= 20

This prevents breaking configurations on unsupported systems.

Loop + Filter (IPv4 Validation)

It loops through a list and runs task only if item is a valid IPv4 address.

when: item | ipv4

This prevents invalid configuration lines from being pushed to devices.

Looping Over Dictionaries (with_dict / dict2items)

It converts a dictionary into a list of key-value pairs.

Dict | dict2items

This is especially powerful in Jinja2 templates.

Using lookup('file')

It reads a file from disk and loads its content.

lookup('file', 'R1_config.txt')

lookup('file', 'R1_config.txt').splitlines()

This converts file content into a list for looping or parsing.

Working with JSON + from_json + json_query

It loads JSON file, Parses it into structured data and Extracts specific values using json_query.

file_d | json_query('devices.*.partitions')

This allows extracting deeply nested data easily.

Saving Facts to JSON

It Stores ansible_facts into a file.

content: "{{ ansible_facts | to_nice_json }}"