Note_Tech

All technological notes.

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Ansible - Playbook

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• Ansible - Playbook
  • Play \& Playbook
    • Components of a play
  • Playbook Verification
  • Syntax Check
  • Ansible Lint

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Play & Playbook

• Module

  • the action defined in a task to be executed
  • common type of module:
    • command
    • script
    • yum
    • service

• Task

  • a list of actions to be performed on the hosts
  • a task is a dictionary
    • but task in a play is a list, the ORDER of tasks matters

• Play

  • a single section within a playbook that maps a set of tasks to a specific group of hosts.
  • Each play defines which hosts to target, what tasks to perform, and optional settings like variables or directives (e.g., gather_facts or become).
  • Purpose: Groups tasks for a specific set of hosts, allowing a playbook to target different hosts or perform different tasks in sequence.
  • Task execution:
    • a play is a dictionary, the position of properties does not matter.
      • But plays in a playbook is list, the position of the plays matters
    • tasks defined within a single play in an Ansible playbook are executed in the order they are listed in the YAML file, from top to bottom.
    • By default, each task must complete (or fail) before the next task begins

• Playbook

  • a list of plays
  • a YAML file that defines a set of automated tasks to be executed on one or more managed hosts.
  • used to organize and orchestrate configuration management, application deployment, or other automation tasks in Ansible.
  • Purpose: Organizes and executes a collection of automation tasks.
  • Play execution:
    • plays in a playbook are executed in the order they are defined in the YAML file.
    • By default, complete all tasks for all targeted hosts in one play before moving to the next play.
      • Ansible operates as a single process on the control node, managing subprocesses for tasks and connections to hosts.

• Command to run a playbook

  • ansible-playbook playbook_file

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Components of a play

• hosts:
  • Specifies the target hosts or groups from the inventory.

• tasks:

  • A list of actions (using Ansible modules) to execute.
• vars:
  • Optional variables for the play.
• gather_facts:
  • Boolean to enable/disable fact collection.

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Playbook Verification

• Good practices to verify playbook before executing in production.

  • Helps in catching the error or unexpected behaviors.

• Type of mode provided for verification:

  • Check mode:
    • execute the playbook without making any actual changes on the hosts, to preview the changes before applying them.
    • command: ansible-playbook playbook_file --check
    • Causion: not all module support check mode
  • Diff mode:
    • run with check mode
    • provide a before-and-after comparison of changes
    • command: ansible-playbook playbook_file --check --diff

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Syntax Check

• Ensure playbook syntax is error-free
• ansible-playbook playbook_file --syntax-check

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Ansible Lint

• Ansible Lint
  • a command-line tool used to check Ansible playbooks, roles, and collections for best practices, potential errors, and style violations.
  • ensures that Ansible code is consistent, maintainable, and adheres to recommended guidelines, helping to catch issues before execution.

ansible-lint playbook.yml
# WARNING  Listing 2 violation(s) that are fatal
# fqcn[action-core]: Use FQCN for builtin module actions (debug).
# get_fact_variable.yaml:4 Use `ansible.builtin.debug` or `ansible.legacy.debug` instead.

# fqcn[action-core]: Use FQCN for builtin module actions (debug).
# get_fact_variable.yaml:8 Use `ansible.builtin.debug` or `ansible.legacy.debug` instead.

# Read documentation for instructions on how to ignore specific rule violations.

#                  Rule Violation Summary
#  count tag               profile    rule associated tags
#      2 fqcn[action-core] production formatting

# Failed: 2 failure(s), 0 warning(s) on 1 files. Last profile that met the validation criteria was 'shared'. Rating: 4/5 star