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Ansible

Getting started video

Getting Started with Ansible | Ansible.com

Architecture

Modules

Modules control system resources, packages, files or nearly anything else. Example apt

module: directive1=value1 directive2=value2

Variables

Variables make it easy to configure and alternate some configurations. Example: a pakcage version, username .. etc. They could be used in playbooks, files, inventories and command line.

Inventories

List of target machines which could be: static servers, ranges, dynamic servers on AWS, GCP ...etc 

[webservers]
www1.example.com
www2.example.com

[dbservers]
db0.example.com
db1.example.com

Playbooks

Plain text YAML files that describe the desired state of something.

Playbooks are Ansible’s configuration, deployment, and orchestration language. They can describe a policy you want your remote systems to enforce, or a set of steps in a general IT process.

If Ansible modules are the tools in your workshop, playbooks are your instruction manuals, and your inventory of hosts are your raw material.

  • Playbooks contains plays
  • Plays contain tasks
  • Tasks contain modules
  • Tasks runs sequentially (mimicking you typing command lines)
  • Handlers are triggered by tasks, and run once at the end of plays.
---
- hosts: webservers
  remote_user: root

  tasks:
  - name: ensure apache is at the latest version
    yum:
      name: httpd
      state: latest
  - name: write the apache config file
    template:
      src: /srv/httpd.j2
      dest: /etc/httpd.conf

- hosts: databases
  remote_user: root

  tasks:
  - name: ensure postgresql is at the latest version
    yum:
      name: postgresql
      state: latest
  - name: ensure that postgresql is started
    service:
      name: postgresql
      state: started

Roles

Roles are special kind of Playbooks that are fully self-contained with tasks, variables, configuration templates and other supporting files.