YAML is a human-readable data format used heavily for configuration in DevOps, Cloud, CI/CD, Kubernetes, Docker Compose, Ansible, Helm, and monitoring systems.

Think in data, not decoration

YAML mainly represents:

• key-value pairs
• lists
• nested objects
• strings
• numbers
• booleans
• multiline values

name: bongoDev
course: DevOps and Cloud Engineering
duration: "4 months"
active: true
students: 200

The same data can be represented in JSON:

{
  "name": "bongoDev",
  "course": "DevOps and Cloud Engineering",
  "duration": "4 months",
  "active": true,
  "students": 200
}

The most important rule: indentation

YAML uses indentation to express hierarchy. Use spaces, not tabs. For bongoDev examples, use 2 spaces per level.

server:
  name: app-server
  port: 8080
  environment: production

Nested structure:

parent:
  child:
    grandchild: value

Key-value pairs

Basic syntax:

key: value

Always put a space after the colon:

# Correct
name: nginx

# Wrong
# name:nginx

Comments

Use # for comments.

# Application configuration
app:
  name: student-api
  port: 3000 # Used by the Node.js backend container

Good comments explain why a value exists rather than repeating the value.