Ansible and YAML for dummies

Yaml examples

Strings

'A single-quoted string in YAML'
"A double-quoted string in YAML\n"

Comments

# Comment on a line

Lists

# A list of tasty fruits
items:
  - Apple
  - Orange
  - Strawberry
  - Mango

# Abbreviated form
items: ['Apple', 'Orange', 'Strawberry', 'Mango']

Dicts

# An employee record dict
martin:
  name: Martin D'vloper
  job: Developer
  skill: Elite

Transforming dictionaries into lists

{{ dict | dict2items }}

Transforming lists into dictionaries

{{ tags | items2dict }}

Ansible

Installation

sudo apt-add-repository ppa:ansible/ansible
sudo apt update
sudo apt install ansible

sudo vi /etc/ansible/hosts

Output /etc/ansible/hosts
[servers]
server1 ansible_host=192.168.1.2
server2 ansible_host=192.168.1.3
server3 ansible_host=192.168.1.4

[servers:vars]
ansible_python_interpreter=/usr/bin/python3

ansible-inventory --list -y

Output
all:
  children:
    servers:
      hosts:
        server1:
          ansible_host: 192.168.1.2
          ansible_python_interpreter: /usr/bin/python3
        server2:
          ansible_host: 192.168.1.3
          ansible_python_interpreter: /usr/bin/python3
        server3:
          ansible_host: 192.168.1.4
          ansible_python_interpreter: /usr/bin/python3
    ungrouped: {}

ssh-keygen -t rsa
ssh-copy-id -i ~/.ssh/id_rsa.pub 192.168.1.2
ssh-copy-id -i ~/.ssh/id_rsa.pub 192.168.1.3
ssh-copy-id -i ~/.ssh/id_rsa.pub 192.168.1.4

Demos

Test conn

ansible all -m ping

ubuntu_test | SUCCESS => { "changed": false, "ping": "pong" }

Run commands

ansible all -a "df -h ."

ubuntu_test | CHANGED | rc=0 >>
Filesystem                         Size  Used Avail Use% Mounted on
/dev/mapper/ubuntu--vg-ubuntu--lv  5.9G  3.0G  2.6G  54% /

To run a play

ansible-playbook playbook.yml

To run demos

git clone https://github.com/rdnovell/ansible_demos 

cd ansible_demos

ansible-playbook include_demo/main.yml

ansible-playbook register_demo/main.yml

ansible-playbook fact_demo/main.yml

ansible-playbook list_demo/main.yml

ansible-playbook role_demo/main.yml

ansible-playbook var_demo/main.yml

ansible-playbook var_files_demo/main.yml

ansible-playbook custom_module_demo/main.yml

ansible-playbook collections_demo/main.yml

Details

Run tasks in parallel for each hosts, not host linear lock

https://docs.ansible.com/ansible/latest/collections/ansible/builtin/free_strategy.html#free-strategy

hosts: all
  strategy: free