EC2

Introduction

Amazon Elastic Compute Cloud (EC2) is a core AWS service that provides resizable virtual servers (instances) in the cloud. EC2 offers a wide range of instance types optimized for different workloads, along with flexible pricing models, storage options, and networking configurations. It forms the foundation of most AWS infrastructure deployments.

Instance Types

EC2 instance types are grouped by family based on the target workload:

Family	Purpose	Example
t3/t4g	General purpose, burstable	Web servers, dev environments
m6i/m7g	General purpose, balanced	Application servers, databases
c6i/c7g	Compute optimized	Batch processing, ML inference
r6i/r7g	Memory optimized	In-memory caches, large databases
i4i	Storage optimized	High I/O databases
p4d/p5	GPU accelerated	ML training, HPC
g5	Graphics intensive	Video encoding, game streaming

Instance naming convention: <family><generation><attributes>.<size> (e.g., m6i.xlarge, c7g.2xlarge)

Pricing Models

• On-Demand: Pay by the second with no commitment
• Reserved Instances: 1 or 3-year commitment for up to 72% discount
• Savings Plans: Flexible pricing with commitment to usage amount ($/hr)
• Spot Instances: Up to 90% discount for interruptible workloads
• Dedicated Hosts: Physical server dedicated to your account for compliance requirements

Key Concepts

AMI (Amazon Machine Image)

AMIs are templates for launching instances:

# List available Amazon Linux AMIs
aws ec2 describe-images \
  --owners amazon \
  --filters "Name=name,Values=al2023-ami-*-x86_64" \
  --query 'Images | sort_by(@, &CreationDate) | [-1].ImageId' \
  --output text

# Launch an instance
aws ec2 run-instances \
  --image-id ami-0abcdef1234567890 \
  --instance-type t3.medium \
  --key-name my-keypair \
  --security-group-ids sg-0123456789abcdef0 \
  --subnet-id subnet-0123456789abcdef0 \
  --tag-specifications 'ResourceType=instance,Tags=[{Key=Name,Value=my-server}]'

Security Groups

# Create a security group
aws ec2 create-security-group \
  --group-name my-sg \
  --description "My security group" \
  --vpc-id vpc-0123456789abcdef0

# Allow SSH and HTTP
aws ec2 authorize-security-group-ingress \
  --group-id sg-0123456789abcdef0 \
  --protocol tcp --port 22 --cidr 10.0.0.0/8

aws ec2 authorize-security-group-ingress \
  --group-id sg-0123456789abcdef0 \
  --protocol tcp --port 80 --cidr 0.0.0.0/0

User Data (Instance Initialization)

aws ec2 run-instances \
  --image-id ami-0abcdef1234567890 \
  --instance-type t3.micro \
  --user-data file://init-script.sh

Example init-script.sh:

#!/bin/bash
yum update -y
yum install -y httpd
systemctl enable --now httpd
echo "Hello from $(hostname)" > /var/www/html/index.html

Instance Lifecycle

# List instances
aws ec2 describe-instances \
  --filters "Name=tag:Name,Values=my-server" \
  --query 'Reservations[].Instances[].[InstanceId,State.Name,PublicIpAddress]' \
  --output table

# Stop / Start / Terminate
aws ec2 stop-instances --instance-ids i-0123456789abcdef0
aws ec2 start-instances --instance-ids i-0123456789abcdef0
aws ec2 terminate-instances --instance-ids i-0123456789abcdef0

EBS Volumes

# Create a volume
aws ec2 create-volume \
  --volume-type gp3 \
  --size 100 \
  --availability-zone us-east-1a \
  --tag-specifications 'ResourceType=volume,Tags=[{Key=Name,Value=data-vol}]'

# Attach to an instance
aws ec2 attach-volume \
  --volume-id vol-0123456789abcdef0 \
  --instance-id i-0123456789abcdef0 \
  --device /dev/xvdf

Reference:

1. Official Website
2. CentOS AWS AMIs