Ansible Usage Guide

Basic Concepts

Common Modules

file

state: touch/directory/absent/link

template

src: /path/to/conf.j2 (local)
dest: /path/to/conf (remote)

user

name: xxx
state: present/absent

authorized_key

user: xxx
state: present/absent
key: /path/to/key.pub

blockinfile

path: /path/to/file
block: |
    ___.   .__                 __    
    \_ |__ |  |   ____   ____ |  | __
    | __ \|  |  /  _ \_/ ___\|  |/ /
    | \_\ \  |_(  <_> )  \___|    < 
    |___  /____/\____/ \___  >__|_ \
        \/                 \/     \/

Variable Precedence

Common variable precedence (later ones have higher precedence)

1. inventory file
2. inventory groups_vars/all
3. inventory host_vars/*
4. include_vars
5. passed in -e key=value

For more on precedence, refer to the documentation

Custom Filters

Ansible implements template replacement and data filters based on Jinja2.

Built-in filters may not always meet your needs, in which case you can create custom filters.

For filter writing, refer to the official filters.

You need to:

1. Create a filter_plugins directory in your playbook directory.
2. Create a Python file in this directory and define a FilterModule class.
3. This class should have a filters method that returns a dictionary, where the key is the filter name and the value is the function implementing the filter.
4. Write your logic within the implementation function.

Note: Use ansible --version | grep "python version" to check the Python version used by Ansible. If you want to use Python 3, refer to this link.

Summary

Why Ansible: automation, modularity, standardization (multi-machine execution, encapsulation abstraction, module reuse)

What Ansible missed: state management (refer to Terraform and K8s)