YAML (YAML Ain’t Markup Language) is a human-readable data serialization language, widely used for configuration files.
📝 Basic Syntax
| 📌 Type | 🧠 Syntax |
|---|
| 📄 String | name: "John Doe" or name: John Doe |
| 🔢 Number | age: 25 or price: 19.99 |
| ✅ Boolean | active: true or active: false |
| 🚫 Null value | value: null |
| 💬 Comment | # This is a comment |
📋 Lists and Objects
| 📌 Action | 🧠 Syntax |
|---|
| 📄 Simple list | - item1
- item2 |
| 📋 Inline list | ports: [80, 443, 8080] |
| 🏗️ Simple object | server:
name: web-01
port: 80 |
| 📊 List of objects | services:
- name: nginx
port: 80 |
📄 Multiline Strings
| 📌 Action | 🧠 Syntax |
|---|
| 📝 Preserve line breaks | script: |
echo "line 1"
echo "line 2" |
| 🔄 Single line | description: >
Long text folded
into one line |
🔥 Practical Examples
🐳 Docker Compose
services:
web:
image: nginx:alpine
ports:
- "80:80"
environment:
- ENV=production
db:
image: postgres:15
environment:
POSTGRES_DB: myapp
POSTGRES_PASSWORD: password
🤖 Ansible
---
- name: Install nginx
hosts: webservers
become: yes
tasks:
- name: Install nginx
apt:
name: nginx
state: present
- name: Start nginx
service:
name: nginx
state: started
🔄 GitHub Actions
name: CI Pipeline
on:
push:
branches: [main]
jobs:
build:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v3
- name: Run tests
run: npm test
- name: Build
run: npm run build
⚠️ Important Rules
| 📌 Tool | 🧠 Usage |
|---|
| 🔍 yamllint | yamllint docker-compose.yml |
| 🔄 yq | yq '.services.web.image' docker-compose.yml |
| 📝 Editors | VSCode, Vim with YAML plugins |
| 🌐 Online validators | yamllint.com, yamlchecker.com |
📋 YAML Checklist
- ✅ Indentation: 2 spaces, no tabs
- ✅ Structure: logical and consistent
- ✅ Validation: test before deployment
- ✅ Comments: explain complex parts
Syspirit