Ansible, there we go again

ansible-notes.md

• To install: pipx install ansible --include-deps
  • If no --include-deps, the actual ansible command, part of ansible-core (a dependency of the ansible metapackage), is not included by pipx
• Some definitions
  • A host is a remote machine managed by Ansible
  • An inventory is a file that describes a list of managed nodes or hosts that are logically organized in groups
  • A module is a unit of work that Ansible ships to a host
    • Usually written in Python (although more languages are supported)
    • They return a JSON and they are removed from the host after execution
    • For example
      • ansible.builtin.setup is called automatically by playbooks during the implicit "Gather Facts" task
      • ansible.builtin.package calls the appropriate module (e.g. ansible.builtin.apt) discovered by ansible.builtin.setup
  • An action is a module and its arguments
  • Is a task a single module with a name, or can be a list of modules ❓
    • The glossary says "(A Task combines) an action with a name and optionally other keywords" and that Tasks is "A list of Task"
    • The getting started page says a Task is "A list of one or more modules"
    • I think there's a bit of terminology abuse here, but let's refer to "tasks" as a list of named modules
  • A play is a mapping between a set of hosts and the tasks to run on them
  • A playbook is a list of plays
  • A role is a redistributable unit of related Ansible artifacts that can be reused in playbooks and represent a single behavior
    • The predefined directory structure supports tasks, handlers, templates, files, variables, defaults, dependencies, and custom stuff (modules, module_utils, other types of plugins)
• Ideally, actions are idempotent, so running them twice is OK
• Have a local hosts file acting as the inventory
• Declare dependencies like with a requirements.yml
  • How do I know that https://galaxy.ansible.com/geerlingguy/docker is a role? Well, you can infer it, but it's not shown anywhere
  • Install with ansible-galaxy install -r requirements.yml

$ cat requirements.yml 
roles:
- name: geerlingguy.docker

• Roles might not work if the user does not have proper permissions (for example if they install new packages)
• By default, --become does not really "become" another user: it is a boolean switch to use sudo
  • To ask for the password, pass -K
• Example playbook to install Docker on some hosts using the aforementioned role:
  • Source: https://galaxy.ansible.com/geerlingguy/docker

$ cat playbooks/main.yml 
- hosts: webservers
  roles:
    - geerlingguy.docker

• To run it: ansible-playbook -i hosts -bK playbooks/main.yml
• A richer example based on the docs:
  • With become: true in the play you don't need -b (-K however is still needed to request the password)
  • But why do I need the YAML front matter --- ❓
  • And what if I want to have both roles and tasks in a single play ❓

---
- name: Docker installed
  hosts: webservers
  become: true
  roles:
    - geerlingguy.docker