AWS EC2

Amazon Elastic Compute Cloud (EC2) provides resizable compute capacity in the cloud.

Advanced patterns (Auto Scaling, Spot Fleets, Session Manager, Instance Connect, IMDS, Placement Groups, scheduled scaling): see instance-management.md.

Table of Contents

• Core Concepts
• Common Patterns
• CLI Reference
• Best Practices
• Troubleshooting
• References

Core Concepts

Instance Types

Graviton (ARM) instances (t4g, m7g, c7g, r7g) are ~20% cheaper than x86 equivalents for the same performance — worth considering for new workloads.

Purchasing Options

AMI (Amazon Machine Image)

Template containing OS, software, and configuration for launching instances. Use SSM Parameter Store to look up the latest official AMIs rather than hardcoding IDs:

# Latest Amazon Linux 2 AMI
aws ssm get-parameter \
  --name /aws/service/ami-amazon-linux-latest/amzn2-ami-hvm-x86_64-gp2 \
  --query 'Parameter.Value' --output text

# Latest Amazon Linux 2023
aws ssm get-parameter \
  --name /aws/service/ami-amazon-linux-latest/al2023-ami-kernel-default-x86_64 \
  --query 'Parameter.Value' --output text

# Latest Ubuntu 22.04
aws ssm get-parameter \
  --name /aws/service/canonical/ubuntu/server/22.04/stable/current/amd64/hvm/ebs-gp2/ami-id \
  --query 'Parameter.Value' --output text

Security Groups

Virtual firewalls controlling inbound and outbound traffic. Changes take effect immediately — no restart required.

Common Patterns

Launch an Instance

# Create key pair
aws ec2 create-key-pair \
  --key-name my-key \
  --query 'KeyMaterial' \
  --output text > my-key.pem
chmod 400 my-key.pem

# Create security group
aws ec2 create-security-group \
  --group-name web-server-sg \
  --description "Web server security group" \
  --vpc-id vpc-12345678

# Allow SSH and HTTP
aws ec2 authorize-security-group-ingress \
  --group-id sg-12345678 \
  --protocol tcp \
  --port 22 \
  --cidr 10.0.0.0/8

aws ec2 authorize-security-group-ingress \
  --group-id sg-12345678 \
  --protocol tcp \
  --port 80 \
  --cidr 0.0.0.0/0

# Launch instance
aws ec2 run-instances \
  --image-id ami-0123456789abcdef0 \
  --instance-type t3.micro \
  --key-name my-key \
  --security-group-ids sg-12345678 \
  --subnet-id subnet-12345678 \
  --associate-public-ip-address \
  --tag-specifications 'ResourceType=instance,Tags=[{Key=Name,Value=web-server}]'

# Wait until running, then get IP
aws ec2 wait instance-running --instance-ids i-1234567890abcdef0
aws ec2 describe-instances \
  --instance-ids i-1234567890abcdef0 \
  --query 'Reservations[].Instances[].PublicIpAddress' --output text

boto3:

import boto3

ec2 = boto3.resource('ec2')

instances = ec2.create_instances(
    ImageId='ami-0123456789abcdef0',
    InstanceType='t3.micro',
    KeyName='my-key',
    SecurityGroupIds=['sg-12345678'],
    SubnetId='subnet-12345678',
    MinCount=1,
    MaxCount=1,
    TagSpecifications=[{
        'ResourceType': 'instance',
        'Tags': [{'Key': 'Name', 'Value': 'web-server'}]
    }]
)

instance = instances[0]
instance.wait_until_running()
instance.reload()
print(f"Instance ID: {instance.id}")
print(f"Public IP: {instance.public_ip_address}")

User Data Script

OS package manager note:

• Amazon Linux 2: use amazon-linux-extras install nginx1 -y — yum install nginx fails because nginx is not in the default AL2 repos
• Amazon Linux 2023: use dnf install -y nginx
• Ubuntu: use apt-get install -y nginx
• Amazon Linux 2 / RHEL: httpd (Apache) is always available via yum install -y httpd

# Amazon Linux 2 — nginx via amazon-linux-extras
aws ec2 run-instances \
  --image-id ami-0123456789abcdef0 \
  --instance-type t3.micro \
  --key-name my-key \
  --security-group-ids sg-12345678 \
  --subnet-id subnet-12345678 \
  --user-data '#!/bin/bash
amazon-linux-extras install nginx1 -y
systemctl start nginx
systemctl enable nginx
'

# Amazon Linux 2 — httpd (Apache, simpler alternative)
# --user-data '#!/bin/bash
# yum install -y httpd
# systemctl start httpd
# systemctl enable httpd
# echo "<h1>Hello from $(hostname -f)</h1>" > /var/www/html/index.html
# '

Attach IAM Role

# Create instance profile
aws iam create-instance-profile \
  --instance-profile-name web-server-profile

aws iam add-role-to-instance-profile \
  --instance-profile-name web-server-profile \
  --role-name web-server-role

# Launch with profile
aws ec2 run-instances \
  --image-id ami-0123456789abcdef0 \
  --instance-type t3.micro \
  --iam-instance-profile Name=web-server-profile \
  ...

Create AMI from Instance

aws ec2 create-image \
  --instance-id i-1234567890abcdef0 \
  --name "my-custom-ami-$(date +%Y%m%d)" \
  --description "Custom AMI with web server" \
  --no-reboot

Auto Scaling Group with Spot (Modern Approach)

The recommended way to use Spot Instances at scale is via Auto Scaling Groups with a mixed-instances policy — not the legacy request-spot-instances API. This supports instance diversification to minimize interruptions.

See instance-management.md for the full setup. Quick example:

# 1. Create launch template with IMDSv2
aws ec2 create-launch-template \
  --launch-template-name my-lt \
  --launch-template-data '{
    "ImageId": "ami-0123456789abcdef0",
    "SecurityGroupIds": ["sg-12345678"],
    "IamInstanceProfile": {"Name": "my-profile"},
    "MetadataOptions": {"HttpTokens": "required", "HttpEndpoint": "enabled"}
  }'

# 2. Create ASG with mixed-instances (Spot + On-Demand diversification)
aws autoscaling create-auto-scaling-group \
  --auto-scaling-group-name my-asg \
  --min-size 0 --max-size 20 --desired-capacity 2 \
  --vpc-zone-identifier "subnet-111,subnet-222" \
  --mixed-instances-policy '{
    "LaunchTemplate": {
      "LaunchTemplateSpecification": {"LaunchTemplateName": "my-lt", "Version": "$Latest"},
      "Overrides": [
        {"InstanceType": "c5.xlarge"},
        {"InstanceType": "c5.2xlarge"},
        {"InstanceType": "c5a.xlarge"}
      ]
    },
    "InstancesDistribution": {
      "OnDemandBaseCapacity": 0,
      "OnDemandPercentageAboveBaseCapacity": 0,
      "SpotAllocationStrategy": "capacity-optimized"
    }
  }'

EBS Volume Management

# Create volume
aws ec2 create-volume \
  --availability-zone us-east-1a \
  --size 100 \
  --volume-type gp3 \
  --iops 3000 \
  --throughput 125 \
  --encrypted

# Attach to instance
aws ec2 attach-volume \
  --volume-id vol-12345678 \
  --instance-id i-1234567890abcdef0 \
  --device /dev/sdf

# Create snapshot
aws ec2 create-snapshot \
  --volume-id vol-12345678 \
  --description "Daily backup"

CLI Reference

Instance Management