Batch 4: Cloud Ansible & OpenShift AWS & Azure Docker & Podman Apache & NGINX ← Full TOC

📋 Ansible Playbooks — Playbook structure, tasks, handlers, variables, loops

Ansible is an agentless automation tool that uses SSH to configure systems. Playbooks are YAML files that define automation tasks. No agent needed on target hosts — only Python and SSH.

📋 Reference

Item	Syntax / Value	Description
Playbook	List of plays targeting host groups	Top-level YAML file: - name: / hosts: / tasks:
Play	Maps hosts to tasks	- name: Configure web servers hosts: webservers become: true
Task	Single unit of work	- name: Install Apache ansible.builtin.apt: name: apache2
Module	Reusable action unit	apt, yum, copy, template, service, command, shell, file, user
Handler	Task triggered by notify	Restart service only when config changed
notify	Trigger a handler	notify: Restart Apache
vars	Variable definitions in play	vars: app_port: 8080
vars_files	Load vars from external YAML file	vars_files: - vars/secrets.yml
group_vars/	Variables for host groups	group_vars/webservers.yml
host_vars/	Variables for specific hosts	host_vars/webserver01.yml
register	Capture task output	register: result - debug: var=result.stdout
when	Conditional task execution	when: ansible_os_family == 'Debian'
loop	Iterate over a list	loop: ['nginx', 'python3', 'git']
with_items	Legacy loop (use loop instead)	with_items: - apache2 - mysql-server
block	Group tasks for error handling	block: / rescue: / always:
become	Privilege escalation (sudo)	become: true become_user: root
tags	Label tasks for selective run	tags: [install, configure]
ignore_errors	Continue on failure	ignore_errors: true
changed_when	Custom changed condition	changed_when: result.rc != 0
failed_when	Custom failure condition	failed_when: result.rc > 1
delegate_to	Run task on different host	delegate_to: localhost
run_once	Run task only once	run_once: true
serial	Rolling update batch size	serial: 2 # or '25%'
pre_tasks / post_tasks	Run before/after roles	pre_tasks: - name: Update cache
gather_facts	Collect host facts (default: true)	gather_facts: false # speeds up if not needed

💡 Example

# site.yml — Complete Ansible Playbook
---
- name: Configure MyWebUniversity Web Servers
  hosts: webservers
  become: true
  gather_facts: true

  vars:
    app_user:    www-data
    app_dir:     /var/www/React/prod
    cgi_dir:     /usr/lib/cgi-bin
    app_port:    80
    app_name:    mywebuniversity

  vars_files:
    - vars/secrets.yml     # vault-encrypted secrets

  pre_tasks:
    - name: Update apt cache
      ansible.builtin.apt:
        update_cache: true
        cache_valid_time: 3600
      when: ansible_os_family == 'Debian'

  tasks:
    - name: Install required packages
      ansible.builtin.apt:
        name:
          - apache2
          - python3
          - python3-pip
          - git
          - curl
        state: present

    - name: Enable Apache CGI module
      community.general.apache2_module:
        name: "{{ item }}"
        state: present
      loop:
        - cgid
        - rewrite
        - ssl
        - headers
      notify: Restart Apache

    - name: Create application directory
      ansible.builtin.file:
        path: "{{ app_dir }}"
        state: directory
        owner: "{{ app_user }}"
        group: "{{ app_user }}"
        mode: '0755'

    - name: Deploy HTML files
      ansible.builtin.copy:
        src:   "files/html/"
        dest:  "{{ app_dir }}/"
        owner: "{{ app_user }}"
        mode:  '0644'
      notify: Reload Apache

    - name: Deploy CGI scripts
      ansible.builtin.copy:
        src:   "files/cgi-bin/"
        dest:  "{{ cgi_dir }}/"
        owner: "{{ app_user }}"
        mode:  '0755'

    - name: Configure Apache virtual host
      ansible.builtin.template:
        src:   templates/vhost.conf.j2
        dest:  /etc/apache2/sites-available/{{ app_name }}.conf
        owner: root
        mode:  '0644'
      notify: Restart Apache

    - name: Enable virtual host
      ansible.builtin.command:
        cmd: a2ensite {{ app_name }}.conf
      changed_when: true
      notify: Restart Apache

    - name: Disable default site
      ansible.builtin.command:
        cmd: a2dissite 000-default.conf
      changed_when: true
      notify: Restart Apache

    - name: Ensure Apache is running and enabled
      ansible.builtin.service:
        name:    apache2
        state:   started
        enabled: true

    - name: Verify web server responds
      ansible.builtin.uri:
        url:    "http://{{ ansible_default_ipv4.address }}/"
        status_code: 200
      register: health_check

    - name: Display result
      ansible.builtin.debug:
        msg: "Server {{ inventory_hostname }} responded: {{ health_check.status }}"

  handlers:
    - name: Restart Apache
      ansible.builtin.service:
        name:  apache2
        state: restarted

    - name: Reload Apache
      ansible.builtin.service:
        name:  apache2
        state: reloaded

# Run: ansible-playbook -i inventory/production site.yml
# Check: ansible-playbook -i inventory/production site.yml --check
# Limit: ansible-playbook -i inventory/production site.yml --limit webserver01
# Tags:  ansible-playbook -i inventory/production site.yml --tags install

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