YAML
📝 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
Indentation
2 spaces per level (no tabs!)Same level = same indentation
Very strict on alignment
Common Mistake
# ❌ WRONG web : server : nginx # Missing indentation port : 80 # Inconsistent
# ✅ CORRECT web : server : nginx port : 80 📌 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 