Level 6: Infrastructure as Code | Tech Knowledge Hub

🖱️ The "ClickOps" Problem

Configuring servers manually (ClickOps) is slow, error-prone, and impossible to replicate perfectly. If you lose the server, you have to remember every single button you clicked to rebuild it.

📜 The IaC Solution

You write a "Blueprint" (Code). You run a tool (Terraform/CloudFormation). The tool builds the servers. If disaster strikes, you just run the code again.

🕵️ Drift Detection

IaC tools ensure your live infrastructure matches your code. If someone manually changes a firewall rule, the IaC tool detects the "Drift" and fixes it automatically.

🏎️ The SysAdmin Race: Manual vs. Code

Player 1: ClickOps

0 / 10

Task: Click the button 10 times. Wait for each to finish.

Player 2: IaC

0 / 10

Task: Write code once. Apply.

          resource "aws_instance" "web" {

            count = 10

            ami = "ami-12345678"

          }

🧠 Imperative vs. Declarative

🗣️ Imperative (Scripting)

You tell the computer HOW to do it.

          # Bash Script

          1. Create Server

          2. Install Nginx

          3. Start Service

If you run this twice, you might get 2 servers or an error.

📜 Declarative (IaC)

You tell the computer WHAT you want.

          # Terraform / CloudFormation

          I want: 1 Server

          State: Running

If you run this twice, nothing happens (because you already have 1 server). This is called Idempotency.

🛠️ The Tool Landscape

Tool	Type	Best For	Description
Terraform	Declarative	Multi-Cloud	The industry standard. Uses HCL language. Works with AWS, Azure, Google, etc.
CloudFormation	Declarative	AWS Only	Native to AWS. Deep integration but verbose (YAML/JSON).
Ansible	Imperative*	Config Management	Best for configuring software inside servers (installing packages, patching).
Pulumi / CDK	Code	Developers	Use real programming languages (Python, TypeScript) to define infrastructure.