Day 1 – Cloud Computing & EC2 Deep Dive | DevOps Learning Log

🔹 Cloud Computing Basics

What Is Cloud Computing?

Cloud computing is the delivery of computing services (servers, storage, networking, databases, etc.) over the internet on a pay-as-you-go basis.

Why Cloud?

• Elasticity: Scale resources up/down automatically

• Cost-Effective: No capex, pay for what you use

• Global Reach: Deploy in multiple regions

• High Availability: Redundancy via Availability Zones

• Speed: Provision resources within minutes

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🔹 Cloud Models

Service Models:

• IaaS (e.g., EC2): Manage OS and everything on top

• PaaS (e.g., Elastic Beanstalk): Just to deploy code

• SaaS (e.g., Gmail): Fully managed end-user apps

Deployment Models:

• Public Cloud (AWS, GCP)

• Private Cloud (on-prem, VMware)

• Hybrid Cloud (combo of both)

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🔹 AWS Overview

• AWS = Most widely adopted cloud platform

• Regions = Geographical locations (e.g., ap-south-1)

• Availability Zones (AZs) = Isolated data centers within a region

• Edge Locations = Used by CloudFront for CDN caching

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🔹 EC2 (Elastic Compute Cloud)

Core Concepts

• AMI (Amazon Machine Image): Pre-configured OS + software

• Instance Types: Compute configs (vCPU, RAM, etc.)

• Pricing Models:

  • On-Demand: Pay per hour/second

  • Reserved: 1-3 year commitment, discounted

  • Spot: Up to 90% cheaper, but can be interrupted

  • Savings Plan: Flexible savings commitment

• Networking:

  • Public IP: Dynamic, changes on stop/start

  • Private IP: Stays within VPC

  • Elastic IP: Static public IP you can remap

• Instance Lifecycle: pending → running → stopped/terminated

• Placement Groups:

  • Cluster: Low latency, high throughput

  • Spread: Instances on separate racks

  • Partition: Split across partitions for failure isolation

• Security Group: Stateful firewall at instance level

• Key Pair: SSH authentication (PEM file used to connect)

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🔹 Hands-On Summary

Launched an EC2 instance using:

• Ubuntu 22.04 AMI

• t2.micro (free tier)

• Custom security group (allow SSH from my IP)

• Connected via SSH using .pem key

• Terminated the instance post-use

Also tested:

• Elastic IP allocation & reassignment

• Instance stop/start behavior on public IP