Introduction to YAML

YAML and its structure

YAML (YAML Ain’t Markup Language) is a data serialization language. In Ansible, we use YAML for writing configuration files because it’s human friendly.

YAML files can either have a .yaml or a .yml file extension. The following code snippet shows two YAML files, config.yaml and config.yml:

config.yaml
config.yml

Components of a YAML file

When we write our configurations using YAML, the overall structure of our configuration is made up of the following major components:

• Document separator
• Key-value pairs
• Indentation
• Lists
• Dictionaries
• Comments

Document separator

YAML files typically start with three hyphens ---. This is optional, but it’s a good practice to always include it in our configuration files. Here is a sample YAML configuration that shows how a YAML file starts:

Key-value pairs

In YAML, we use key-value pairs to define properties of elements. A key is typically followed by a colon (:) and then the corresponding value. Whether the value needs to be enclosed in quotes or not depends on its data ...