EC2

Learning objectives#

• Launch an EC2 instance
• Choose an instance type and AMI
• Bootstrap software with user data
• Attach a role and secure access

Explanation#

An AMI (Amazon Machine Image) is the OS template. Instance types combine family and size: t3.micro (burstable), m7i.large (general purpose), c7g (compute, Graviton ARM).

Storage is usually an EBS volume — a network disk that persists when the instance stops.

Security groups act as a firewall. User data runs a script on first boot to install software.

Attach an IAM instance profile (role) so code on the instance can call AWS APIs without keys. Prefer Session Manager over opening SSH.

Code example: Launch a web server#

1aws ec2 run-instances \
2  --image-id resolve:ssm:/aws/service/ami-amazon-linux-latest/al2023-ami-kernel-default-x86_64 \
3  --instance-type t3.micro \
4  --security-group-ids sg-0web123 \
5  --subnet-id subnet-0pub123 \
6  --iam-instance-profile Name=web-ssm-role \
7  --user-data file://user-data.sh \
8  --tag-specifications 'ResourceType=instance,Tags=[{Key=Name,Value=web-1}]'
9

10# user-data.sh
11#!/bin/bash
12dnf install -y nginx
13systemctl enable --now nginx
14

15aws ssm start-session --target i-0abc123def456     # shell access without SSH

{
  "Instances": [{ "InstanceId": "i-0abc123def456", "InstanceType": "t3.micro", "State": { "Name": "pending" } }]
}

This example is illustrative. Copy or download it and run it in your own environment; the expected output is shown above.

Step-by-step explanation#

1. The AMI ID is resolved from a public SSM parameter so you always get the latest Amazon Linux 2023.
2. The security group controls inbound ports.
3. The instance profile grants permissions (here, Session Manager access).
4. User data installs and starts Nginx on first boot.
5. Session Manager opens a shell with no port 22 open.

Real-world use case#

Common mistakes#

Best practices#

• Use instance roles, not keys
• Use Session Manager instead of SSH
• Stop or schedule dev instances
• Use Auto Scaling groups for production instead of single instances

Remember this#

Practice exercise#

1aws ec2 stop-instances --instance-ids i-0abc123def456
2aws ec2 start-instances --instance-ids i-0abc123def456

Mini quiz#

Want more? Practise all AWS MCQs · AWS interview questions

Related topics#

My notes#

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