Ansible

Ansible
Author

Benedict Thekkel

🧰 What Is Ansible?

Ansible is an open-source IT automation and configuration management tool originally created by Michael DeHaan, now maintained by Red Hat.

It automates:

  • Server configuration
  • Application deployment
  • Infrastructure orchestration
  • Networking
  • Security hardening
  • CI/CD tasks

Unlike many tools, it is agentless (uses SSH by default).

🧠 Core Philosophy

Principle Meaning
Agentless No software installed on target machines
Declarative-ish You define desired state
Idempotent Safe to run multiple times
YAML-based Human-readable playbooks
Push model Controller pushes changes

🏗 How Ansible Works

Control Node (your machine)
        |
        | SSH
        v
Managed Nodes (servers, VMs, containers)

It:

  1. Connects via SSH
  2. Copies module temporarily
  3. Executes
  4. Removes module
  5. Reports result

📦 Core Components

1️⃣ Inventory

Defines hosts:

[web]
192.168.1.10
192.168.1.11

[db]
db.local

Or dynamic (AWS, Azure, etc.).

2️⃣ Playbooks

YAML automation definitions:

- name: Install Nginx
  hosts: web
  become: yes

  tasks:
    - name: Install package
      apt:
        name: nginx
        state: present

Run:

ansible-playbook site.yml

3️⃣ Modules

Reusable actions.

Examples:

Category Modules
Packages apt, yum
Files copy, template
Services service
Cloud ec2, azure_rm
Containers docker_container
K8s k8s

Over 3000+ modules available.

4️⃣ Roles (Reusable Structure)

Standard layout:

roles/
  nginx/
    tasks/
    handlers/
    templates/
    vars/

Use in playbook:

roles:
  - nginx

🔁 Idempotency

If nginx is already installed:

state: present

It does nothing.

Safe to rerun anytime.

🧩 Variables

vars:
  http_port: 80

Override with:

  • inventory
  • group_vars
  • host_vars
  • extra vars

🔐 Privilege Escalation

become: yes
become_method: sudo

🌍 Dynamic Inventory

For cloud:

ansible-inventory -i aws_ec2.yml --graph

Supports:

  • AWS
  • Azure
  • GCP
  • VMware

🏗 Real-World Example

Provision + configure:

- hosts: all
  become: yes

  tasks:
    - name: Update apt
      apt:
        update_cache: yes

    - name: Install Docker
      apt:
        name: docker.io
        state: present

🧠 Advanced Features

1️⃣ Templates (Jinja2)

- name: Configure Nginx
  template:
    src: nginx.conf.j2
    dest: /etc/nginx/nginx.conf

Dynamic config generation.

2️⃣ Handlers

Triggered only on change:

handlers:
  - name: Restart nginx
    service:
      name: nginx
      state: restarted

3️⃣ Loops

- name: Create users
  user:
    name: "{{ item }}"
  loop:
    - ben
    - admin

4️⃣ Conditionals

when: ansible_os_family == "Debian"

5️⃣ Tags

ansible-playbook site.yml --tags nginx

☁ Ansible + Cloud

You can:

  • Create EC2 instances
  • Configure them
  • Deploy apps

Often used alongside:

Terraform

Common pattern:

Tool Purpose
Terraform Create infrastructure
Ansible Configure OS + apps

🏢 Ansible Tower / Automation Platform

Red Hat Ansible Automation Platform

Provides:

  • Web UI
  • RBAC
  • Scheduling
  • API
  • Credential storage

🔄 Push vs Pull

Model Example
Push Ansible
Pull Puppet, Chef

Push = you run it. Pull = nodes check in.

🛠 Comparison With Other Tools

Tool Agentless Language Focus
Ansible ✅ YAML Config mgmt
Puppet ❌ DSL Large infra
Chef ❌ Ruby Enterprise
SaltStack Mixed YAML Speed
Terraform N/A HCL Infra provisioning

🧱 When To Use Ansible

Use it for:

  • OS configuration
  • Deploying Django app
  • Installing Docker
  • Hardening Linux
  • Rolling updates
  • Managing clusters

🚫 When NOT To Use It

Not ideal for:

  • Creating thousands of cloud resources (Terraform better)
  • High-frequency config drift enforcement
  • Event-driven infra (use Kubernetes or cloud-native tools)

🏗 Production Best Practices

Structure

inventory/
  production
  staging

roles/
  app/
  db/

site.yml

Use Vault

Encrypt secrets:

ansible-vault encrypt secrets.yml

Lint & Testing

  • ansible-lint
  • molecule (role testing)
  • CI/CD validation

🔥 Example: Deploy Django App

  1. Install Python
  2. Install Postgres
  3. Clone repo
  4. Setup venv
  5. Run migrations
  6. Configure Gunicorn
  7. Configure Nginx
  8. Setup systemd

All via one playbook.

📊 Ansible Execution Flow

Inventory → Playbook → Tasks → Modules → Results

🧠 Scaling Considerations

For large infra:

  • Use forks
  • Use SSH control master
  • Use fact caching
  • Use Tower for job scheduling

🔮 Future of Ansible

  • Event-driven automation
  • Integration with GitOps
  • Cloud-native modules
  • Improved execution speed

🏁 Summary

Ansible is best for:

✔ Server configuration ✔ Application deployment ✔ Cloud VM setup ✔ Security automation ✔ CI/CD provisioning

Pair it with Terraform for full infra lifecycle.

If you’d like, I can next give:

  • 🏗 Ansible for Proxmox homelab
  • 🚀 Deploy Django + Postgres + Nginx with Ansible
  • 🔐 Advanced Ansible security patterns
  • ⚔ Terraform vs Ansible deep comparison
  • 🧠 Ansible performance tuning guide

Tell me what direction you want.

Back to top