yaml

 yaml

YAML (YAML Ain't Markup Language) is a human-readable data serialization format designed for structure and simplicity. It is the industry standard for configuration files across tools like Docker, Kubernetes, GitHub Actions, and Ansible.

Core Syntax & Primitive Types

Key-Value Pair name: Alex Developer Space after the colon is strictly required.

Comments # Single-line comment Begins with #. Multi-line comments don't exist.

Data Types age: 28 / active: true Integers, floats, booleans, and null (~ or null) are auto-inferred.

Strings title: "System Lead" Quotes are optional unless handling special characters or numbers.

Lists & Maps

YAML structures data using indentation. Indentation must use spaces only—tabs are invalid syntax.

YAML

# Nested Mapping (Object)

database:

  host: localhost

  port: 5432

  credentials:

    user: admin

# Sequence (List/Array)

frameworks:

  - React

  - Vue

  - Angular

# Inline Syntax (JSON-style alternative)

compact_list: [1, 2, 3]

compact_map: { x: 10, y: 20 }

Multi-Line Strings

• Literal Block (|): Preserves all newlines exactly as written.

• Folded Block (>): Converts single newlines into spaces, combining lines into a continuous paragraph.

YAML

literal_text: |

  Line 1

  Line 2 (newline preserved)

folded_text: >

  This text spans multiple lines

  but will render as a single paragraph.

Anchors & Aliases (DRY Configuration)

You can reuse repeated blocks of data using & to define an anchor and * to reference it:

YAML

default_config: &default_env

  timeout: 30

  retries: 3

production:

  <<: *default_env  # Merges default_config keys here

  host: prod.example.com

Common Pitfalls

• Tabs vs. Spaces: Using a tab character breaks the parser. Set your editor to insert spaces.

• Boolean Coercion: Unquoted values like yes, no, true, false, on, off, N, or Y are automatically cast as booleans in YAML 1.1. Always quote country codes like "NO" (Norway).