Data Formats and Templates (JSON, YAML, Jinja2)

Network automation depends on separating data (what you want to configure) from logic (how to apply it). Data formats like JSON and YAML store device variables, while template engines like Jinja2 generate device-specific configurations from those variables.

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Why Separate Data from Templates?

Approach	Problem
Hardcoded configs	Every device needs a separate script; changes require editing code
Data + Template	Write the template once, feed in different data for each device

Data (YAML)          +    Template (Jinja2)     =    Device Config
─────────────             ──────────────              ──────────────
hostname: R1              hostname {{ hostname }}      hostname R1
mgmt_ip: 10.0.0.1        interface Mgmt0              interface Mgmt0
                           ip address {{ mgmt_ip }}     ip address 10.0.0.1

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JSON (JavaScript Object Notation)

JSON is a lightweight, text-based data format widely used by APIs and automation tools:

Syntax Rules