Ansible

Written in Python. The Ansible controller requires Python.
Ansible follows the principle of idempotence — you can run automation repeatedly and it only makes changes when necessary.
Ansible uses the Jinja2 templating engine for variable replacement, loops, conditionals, and data manipulation.

---

Keywords

• Community
  The easiest way for most admins to run Ansible. It contains Ansible binaries and many commonly used components packaged and ready to go.

• Core
  A minimal distribution containing only essential components. Developers or admins who want a lightweight install use this; additional components may be required to automate most hosts.

• Navigator
  Builds on top of Ansible Core by allowing executions inside containers called Execution Environments (EEs).

• Container
  A portable unit bundling code, runtime, libraries, and dependencies to run an application consistently across environments.

• API
  Application Programming Interface.

• Playbooks
  Scripts consumed by the Ansible binary to perform automation.

  • A playbook tells each play where to run and what to do.
  • A playbook can contain multiple plays (different sets of hosts).
  • The name field is optional but highly recommended — it documents intent and appears in output.

• Tasks
  Ordered list of discrete automation steps executed in sequence. By default Ansible completes the first task for all hosts before moving to the next.

• Module
  A piece of code (usually Python or PowerShell) that performs an automation action.

• Collection
  An archive (tar) that installs modules, roles, plugins, playbooks, docs, and other objects. Use the Fully Qualified Collection Name (FQCN) to reference modules.

• Inventory
  A list of hosts you can operate against. Think of the inventory as a menu — the hosts declaration in a playbook is the specific order you pick from that menu. Inventories are typically stored as INI or YAML files.

• YAML
  Defines layout and structure — indentation matters:

  • Use spaces, not tabs.
  • Tabs will break playbooks.
  • Two spaces is a common indentation rule.
  • Many mistakes are due to incorrect spacing.

• Variables
  Important for flexibility and fact gathering. Ansible has many precedence levels (22 levels). Use variables as {{ variable_name }}.

• AWX
  A web UI and job controller for Ansible. AWX provides:

  • Role-based access control (RBAC)
  • A GUI and REST API
  • Job logging and execution control

• Python Virtual Environment (PVE)
  Lets you manage different Python package versions per environment. When managing many dependencies, consider Execution Environments and Ansible Navigator instead.

---

Installation

# Install Python (Fedora/RHEL example)
sudo dnf install -y python3

# Install pip
sudo dnf install -y python3-pip

# Install Ansible
pip install ansible

# Update Ansible
pip install --upgrade ansible

# Verify
ansible --version

If you have SSH issues from macOS hosts, you may need Paramiko:

pip install paramiko

---

Commands

• pwd — Present Working Directory
• ls — List files
• clear — Clear terminal
• --ask-pass — Prompt for SSH password
• --ask-become-pass — Prompt for privilege escalation (become) password

---

Examples

1. Gather facts and display them

   ---
   - name: Gather facts and display them
     hosts: LL-Test
     tasks:
       - name: Display all gathered facts
         ansible.builtin.debug:
           var: ansible_facts
   
       - name: Display the currently running kernel version and distro
         ansible.builtin.debug:
           msg: "The kernel version is {{ ansible_facts.kernel }} and the distribution is {{ ansible_facts.distribution }}"
   

   Run:

   ansible-playbook -i inventory gather-facts.yml
   

---

1. Quick webserver install and config

   ---
   - name: Quick webserver install and config
     hosts: LL-Test
     gather_facts: false
     become: true
     tasks:
       - name: Install apache webserver
         ansible.builtin.package:
           name: httpd
           state: present
   
       - name: Start and enable apache
         ansible.builtin.service:
           name: httpd
           state: started
           enabled: true
   
       - name: Write a simple index.html file
         ansible.builtin.lineinfile:
           path: /var/www/html/index.html
           line: "<h1>Hello world!</h1>"
           create: true
   

   Run:

   ansible-playbook -i inventory webserver.yml
   # then test with:
   curl http://127.0.0.1
   

---

1. Vars, conditionals and loops

   ---
   - name: Vars, conditionals and loops
     hosts: LL-Test
     gather_facts: false
     vars:
       nums:
         - 1
         - 10
         - 20
         - 25
         - 30
     tasks:
       - name: Display any numbers larger than 10
         ansible.builtin.debug:
           msg: "{{ item }}"
         loop: "{{ nums }}"
         when: item > 10
   

---

Idempotence output

• OK — Task completed successfully and no change was needed.
• Changed — Task completed and made a change on the host.
• Failed — Task failed for this host (error details are shown).
• Skipping — Condition not met, so task was skipped.

---

Installing Collections

1. Install a collection:

   ansible-galaxy collection install <namespace.collection_name>
   

2. Check repository requirements.txt for Python dependencies. If a requirements.txt URL is provided, you can install its Python deps:

   pip install -r <requirements.txt-raw-url>
   

---