YAML

YAML#

Yet Another Markup Language
2001
Natural and Meaningful (Human Readable)
DataTypes
- Scalars, Lists, Arrays
Data Structures
- Indentation, dahses, colons
Common uses
- Config files
- Storing data

YAML only supports spaces Supports Unicode

Two styles:

Block styles Better for humans Less Compact

host: phl-42
datacenter:
  location: Phil
  cab: 14
roles:
  - web
  - some toher

Flow styles Compact, extension of json, folding, tags and anchors

host: "phl-42"
datacenter: {location: Phil, cab: 14} # need to be on same line and commas between values
roles: [web,some toher]

Mappings, Sequences#

host: phl-42 # space between key: value is important
datacenter:
  location: phil #2 space indentations
  cab: 13
roles: 
  - webserver
  - wp_database # sequences cannot be wihtout mapping or blank

Scalars#

String, number, or boolean

String: '' or "", double string allows for escape sequence Multiline: | or > Lots of multiline string

Structures#

You can add multiple directives/documents in one files

add --- to the top of file when building multidocument file

e.g.

---
host: phl2
---
host: someother

Comments#

# octothorpe space and the comment to add a comment in YAML

Tags#

Setting a cstom URI
Setting local tags
Setting a data type

host: phl-42
datacenter:
  location: phil
  cab: !!str 13 # !!str changes the datatype to str more !!int !!float
roles: 
  - webserver
  - wp_database

Anchors#

Anchors allow to store and reuse data

host: phl-42
datacenter:
  location: &PHL phil # now can referrence this anywhere with *PHL
  cab: !!str 13 # !!str changes the datatype to str more !!int !!float
roles: 
  - webserver
  - wp_database

Wrote a simple YAML file for ansible to install MariaDB

---
- hosts: localhost
  remote_user: ansible
  become: yes
  become_method: sudo
  connection: ssh
  gather_facts: yes
  tasks:
    - name: Installing MariaDB
      yum:
        name: mariadb-server
        state: latest
      notify:
        - startservice
  handlers:
    - name: startservice
      service:
        name: mariadb
        state: restarted