DAY3 -Monitoring & Scaling

Source: Dev.to

Overview

Today’s hands‑on lab covers monitoring and scaling EC2 instances using an Application Load Balancer (ALB), an Auto Scaling Group (ASG), and CloudWatch.

Network Setup

• Subnet: Use the public subnet created in the Day 1 hands‑on.
• Route: Add a default route to the private route table associated with private subnets so that instances in those subnets can reach the Internet.

Security Groups

ALB Security Group

• Inbound: HTTP 80 from 0.0.0.0/0
• Outbound: All traffic (default)

EC2 Security Group

• Inbound: HTTP 80 from the ALB security group created above
• Outbound: All traffic (default)

Target Group

• Target type: Instances

Launch Template

Create a launch template for the ASG with the following settings:

• AMI: Amazon Linux 2023
• User data:

#!/bin/bash
set -e

dnf -y update
dnf -y install nginx
systemctl enable --now nginx

TOKEN=$(curl -s -X PUT "http://169.254.169.254/latest/api/token" \
  -H "X-aws-ec2-metadata-token-ttl-seconds: 21600")
INSTANCE_ID=$(curl -s -H "X-aws-ec2-metadata-token: $TOKEN" \
  http://169.254.169.254/latest/meta-data/instance-id)

cat > /usr/share/nginx/html/index.html <<EOF

## Day3: ALB + ASG (Private EC2)

InstanceId: ${INSTANCE_ID}

EOF

Auto Scaling Group (ASG)

• Launch template: Use the template created above.
• Scheme: Internet‑facing

After the ASG is created, verify that the ALB’s DNS name loads the page showing the instance ID. Ensure the target group status is healthy.

Scaling Policy

1. In the ASG console, navigate to Automatic scaling → Create dynamic scaling policy.
2. Connect to an EC2 instance via SSM (as in Day 2) and run the following commands to generate CPU load for ten minutes:

sudo dnf -y install stress-ng
cd /tmp
stress-ng --cpu 2 --timeout 10m

3. Wait a few minutes and observe the scaling activity in the ASG dashboard.

Cleanup Order

Delete resources in the following order to avoid dependency failures:

1. Auto Scaling Group
2. Launch template
3. ALB and target group
4. Subnets, route tables, and NAT resources
5. Security groups

Key Exam Points

• NAT Gateway: Managed service; automatically associated with an Elastic IP (EIP).
• NAT Instance: EC2 instance with an EIP or public IP; you must manage failover and load balancing.

ALB vs. NLB

Scaling of Resources

• EC2: ASG + ALB/NLB + scaling metrics (CPU, request count, etc.)
• Lambda: Concurrency limits, driven by event sources (SQS, Kinesis, etc.)
• ECS/EKS: Service Auto Scaling

See you soon in Day 4 hands‑on!