AWS EC2: Launch a New Instance

Launching an EC2 Instance

The aws ec2 run-instances command creates and starts one or more EC2 instances. It requires at minimum an AMI ID and instance type.

Minimal Launch Command

aws ec2 run-instances \
  --image-id ami-0abcdef1234567890 \
  --instance-type t3.micro \
  --count 1

Production-Ready Launch

aws ec2 run-instances \
  --image-id ami-0abcdef1234567890 \
  --instance-type t3.medium \
  --count 1 \
  --key-name my-ssh-key \
  --security-group-ids sg-0123456789abcdef0 \
  --subnet-id subnet-0abc123def456789 \
  --tag-specifications 'ResourceType=instance,Tags=[{Key=Name,Value=WebServer},{Key=Environment,Value=production}]' \
  --region us-east-1

Key Parameters

Flag	Purpose
--image-id	AMI ID — the operating system image
--instance-type	CPU and memory configuration (t3.micro, m5.large, etc.)
--count	Number of instances to launch
--key-name	SSH key pair for remote access
--security-group-ids	Firewall rules (can specify multiple)
--subnet-id	VPC subnet to place the instance in
--tag-specifications	Tags for naming and organizing

Finding the Right AMI

aws ec2 describe-images \
  --owners amazon \
  --filters "Name=name,Values=amzn2-ami-hvm-*-x86_64-gp2" \
  --query "sort_by(Images, &CreationDate)[-1].ImageId" \
  --output text

With User Data (startup script)

aws ec2 run-instances \
  --image-id ami-0abcdef1234567890 \
  --instance-type t3.micro \
  --user-data file://startup-script.sh \
  --count 1

The user data script runs as root when the instance first boots.