Ansible Playbook

Ansible Playbook Development

Overview

Ansible playbooks declare desired system state rather than imperative commands. The core principle is idempotency: running a playbook multiple times produces the same result without unintended changes.

When to Use

• Creating new playbooks or roles
• Writing inventory files
• Debugging YAML syntax errors
• Troubleshooting module parameter issues
• Understanding variable precedence
• Converting shell scripts to Ansible

Quick Reference

Project Structure

project/
├── ansible.cfg          # Configuration
├── inventory            # Host definitions
├── group_vars/          # Group variables
├── host_vars/           # Host-specific vars
├── roles/               # Reusable roles
└── playbooks/           # Playbook files

Essential ansible.cfg

[defaults]
inventory = ./inventory
roles_path = ./roles
host_key_checking = False
stdout_callback = yaml

[privilege_escalation]
become = True
become_method = sudo

Module Patterns

| Operation | Module | Key Parameters | |-----------|--------|----------------| | Create directory | ansible.builtin.file | state: directory, mode, owner | | Copy file | ansible.builtin.copy | src, dest, mode | | Template | ansible.builtin.template | src, dest, variables in .j2 | | Install package | ansible.builtin.package | name, state: present | | Manage service | ansible.builtin.service | name, state, enabled | | Run command | ansible.builtin.command | cmd, register result, set changed_when |

Variable Precedence (lowest to highest)

1. Role defaults (defaults/main.yml)
2. Inventory group_vars
3. Inventory host_vars
4. Playbook vars
5. Role vars (vars/main.yml)
6. Task vars
7. Extra vars (-e)

Handlers

tasks:
  - name: Update config
    ansible.builtin.template:
      src: app.conf.j2
      dest: /etc/app.conf
    notify: Restart app

handlers:
  - name: Restart app
    ansible.builtin.service:
      name: app
      state: restarted

Error Handling

- block:
    - name: Risky operation
      ansible.builtin.command: /opt/app/upgrade.sh
  rescue:
    - name: Handle failure
      ansible.builtin.debug:
        msg: "Upgrade failed, rolling back"
  always:
    - name: Cleanup
      ansible.builtin.file:
        path: /tmp/upgrade.lock
        state: absent

Common Mistakes

| Mistake | Fix | |---------|-----| | Using short module names | Always use FQCN: ansible.builtin.copy not copy | | Hardcoded values | Extract to variables in defaults/main.yml | | Missing changed_when on commands | Add changed_when: "'created' in result.stdout" | | Forgetting handler flush | Use meta: flush_handlers when needed before dependent tasks | | YAML indentation errors | Use 2 spaces, never tabs | | Colon in unquoted string | Quote values containing : |

Verification Commands

ansible-playbook --syntax-check playbook.yml  # Check YAML
ansible-playbook --check playbook.yml         # Dry run
ansible-playbook --check --diff playbook.yml  # Show file changes
ansible-inventory --list                       # Verify inventory
ansible-inventory --host hostname             # Check host vars

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: sigridjineth
• Source: sigridjineth/hello-ansible-skills
• License: MIT

Install and usage instructions live in the source repository linked above.