View source for Introduction to YAML

[[Category: rchan]]
= What is YAML? =
* YAML stands for "YAML Ain’t markup language"
* It is a human-readable data serialization language that is used in Ansible to package output and its playbooks

= What are the major components in YAML?=
* declarations: name: 'yum'
* lists:
:: - 'item_a'
:: - 'item_b'
:: - 'item_c'
* associative arrays:
:: item_a:
::: name: 'Name A'
::: id: '12345678'
:: item_b:
::: name: 'Name B'
::: id: '98765432'
= Some examples: file written in YAML =
== YAML File and Python ==
File name: students.yaml
<pre>
students:   
  - name: David     
    id_number: 012345678     
    program: CTY   
  - name: Raymond
    id_number: 112001987
    program: CNS 
</pre>
The above file contains data equivalent to the following dictionary data object in Python:
<pre>
{'students': [{'id_number': '012345678', 'name': 'David', 'program': 'CTY'}, 
{'id_number': 112001987, 'name': 'Raymond', 'program': 'CNS'}]}
</pre>
The contents of students.yaml can be created by the following python code:
<pre>
#!/usr/bin/env python3
import yaml

students = {'students': [{'name': 'David', 'id_number': '012345678', 'program': 'CTY'},
            {'name': 'Raymond', 'id_number': 112001987, 'program': 'CNS'}]}

print(yaml.dump(students))
</pre>
== Ansible playbooks ==
File Name: get_os_version.yaml
<pre>
---
- hosts: all
  remote_user: rchan
  tasks:
  - name: Print Linux distribution and version
    debug:
       msg: '{{ ansible_distribution }} {{ ansible_distribution_version }}'
</pre>
The file above contains data equivalent to the following data object in Python:
<pre>
[{'hosts': 'all', 'remote_user': 'rchan', 'tasks': [{'debug': {'msg': '{{ ansible_distribution }}
 {{ ansible_distribution_version }}'}, 'name': 'Print Linux distribution and version'}]}]
</pre>