YAML, which stands for “YAML Ain’t Markup Language” (a playful recursive acronym), is a human-readable data serialization format. It’s often used for configuration files, data exchange between languages with different data structures, and in scenarios where data needs to be both machine-readable and human-readable. YAML files use indentation and whitespace to structure data, making them easier to read for humans compared to formats like JSON or XML.
Key characteristics of YAML include:
- Simple Syntax: YAML uses a minimalist and intuitive syntax. It relies on indentation (whitespace) to denote the structure of the data, with colons (“:”) used to separate keys and values.
- Data Types: YAML supports various data types, including scalars (strings, numbers, booleans), sequences (arrays or lists), and mappings (key-value pairs or dictionaries).
- Comments: YAML allows for comments to be included using the “#” symbol, making it easy to add explanatory notes in the configuration files.
- Inclusion of External Data: YAML supports the inclusion of external data from other YAML files, making it easy to split data into multiple files and reuse components.
Here’s a simple example of YAML syntax:
name: John Doe
age: 30
email: johndoe@example.com
hobbies:
- Reading
- Hiking
- Cooking
In this example, “name,” “age,” and “email” are keys with associated values, and “hobbies” is a key with a list of values.
YAML is commonly used in various applications and programming languages, including:
- Configuration Files: Many software applications, including web frameworks and content management systems like WordPress, use YAML for configuration files.
- Ansible: A popular automation tool that uses YAML for defining tasks, plays, and playbooks.
- Docker Compose: YAML is used to define services and configurations in Docker Compose files.
- Jenkins Pipeline: Used for defining CI/CD pipelines in Jenkins.
- Kubernetes: YAML is used for defining resources like pods, services, and deployments.
- Markdown Front Matter: In some cases, YAML is used in the front matter of Markdown files to store metadata about the document.
YAML’s readability and flexibility make it a popular choice for configuration files and data exchange, and it’s widely used in the software development and DevOps communities.