YAML Introduction

YAML - YAML Ain't Markup Language

YAML is a human-readable data serialization language. It is commonly used for configuration files and for describing structured data in tools such as Kubernetes, GitHub Actions, and Docker Compose.

Example:

name: Pradumna
age: 21
address: 
  city: Bangalore
  state: Karnataka
  country: India
  phone:
    office: 0000000
    home: 
        - 1111111
        - 2222222

Properties

• Similar in purpose to JSON and XML.
• Designed for data, not executable commands.
• Sensitive to indentation and spacing.
• Easy for humans to read when formatted clearly.

Syntax

Key-value pair

Name: "Pradumna Saraf"
1: "This is a value"

List

- apple
- mango
- Banana
- banana

or

cities: [new delhi, patna, gujarat]

String and Variables

name: Pradumna Saraf
fruit: "Mango"
job: 'Advocate'
age: 65
marks: 10.33
booleanValue: false

Multiline String

Address: |
  01
  Delhi
  India

Folded style joins multiple lines into a single string.

message: >
  This all
  will be in a single
  line

Nested Mapping

names: Pradumna
role:
  age: 22
  job: student

Nested Sequence

-
  - mango
  - apple
  - banana
-
  - marks
  - roll

Specify the data type

# Integer
Zero: !!int 0
positiveNumber: !!int 45
negativeNumber: !!int -45
hexa: !!int 0x45

# Float
mark: !!float 56.55
infinity: !!float .inf
not a num: .nan
itNot: !!bool false

# String
string: !!str "hello"

# Null
surname: !!null #null or NULL ~ 
~: this a null key

# Exponential Numbers
myNum: 6.22E56

# Dates and time
date: !!timestamp 2002-01-02
no Time zone: 2012-12-15T02:59:43
India Time: 2012-12-15T02:59:43 +5:30

Usage

• Used in Kubernetes, Ansible, Docker, and many other tools.
• Useful for storing data in key-value form.
• Common in CI/CD systems like GitHub Actions and CircleCI.

What's next?

• Learning Resources - Learn more about YAML with these resources.
• Tools - Learn about the tools that you can use with YAML.