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Cloud (AWS) Day 07: Change EC2 Instance Type

This document outlines the solution for the seventh task in the AWS migration strategy: resizing an existing EC2 instance to optimize cost and resource utilization.

We will cover two methods to achieve this: 1. AWS Management Console (UI) 2. AWS Command Line Interface (CLI)

Task Requirements

  • Target Instance: xfusion-ec2
  • Current Type: t2.micro
  • New Type: t2.nano
  • Region: us-east-1 (N. Virginia)
  • Conditions: * Wait for status checks to complete before making changes.
    • Ensure the instance is in the Running state after the change is complete.

The Golden Rule of Resizing EC2 Instances

You cannot change an instance type while the instance is running. The instance must be transitioned to the Stopped state first. This is because AWS needs to migrate your virtual machine to different underlying physical hardware that supports the new instance type specifications.

Method 1: Using the AWS Management Console (UI)

Step 1: Login & Navigate

  1. Open the Console URL provided in your credentials.
  2. Log in with the Username and Password.
  3. Ensure you are in the N. Virginia (us-east-1) region.
  4. In the search bar, type EC2 and select EC2 under Services.
  5. Click on Instances (running) in the main dashboard.

Step 2: Verify Status Checks

  1. Locate the instance named xfusion-ec2.
  2. Look at the Status check column.
  3. If it says Initializing, wait until it displays 2/2 checks passed.

Step 3: Stop the Instance

  1. Select the checkbox next to xfusion-ec2.
  2. Click the Instance state dropdown menu at the top right.
  3. Select Stop instance, and confirm by clicking Stop in the pop-up modal.
  4. Wait for the "Instance state" column to change from Stopping to Stopped.

Step 4: Change Instance Type

  1. Ensure xfusion-ec2 is still selected.
  2. Click the Actions dropdown menu.
  3. Navigate to Instance settings -> Change instance type.
  4. In the "Instance type" dropdown, search for and select t2.nano.
  5. Click Apply.

Step 5: Start the Instance

  1. With xfusion-ec2 selected, click the Instance state dropdown menu.
  2. Select Start instance.
  3. Wait a few moments until the state says Running. The task is now complete.

Method 2: Using the AWS CLI

This method executes the entire workflow via the terminal on the aws-client host.

Step 1: Get the Instance ID

First, dynamically fetch the instance ID based on the tag name.

INSTANCE_ID=$(aws ec2 describe-instances \
    --filters "Name=tag:Name,Values=xfusion-ec2" \
    --query "Reservations[*].Instances[*].InstanceId" \
    --output text \
    --region us-east-1)

echo "Instance ID is: $INSTANCE_ID"

Step 2: Wait for Status Checks to Complete

Ensure the instance has fully initialized before disrupting it. The wait command will pause the terminal until the condition is met.

echo "Waiting for status checks to complete..."
aws ec2 wait instance-status-ok \
    --instance-ids $INSTANCE_ID \
    --region us-east-1
echo "Status checks passed."

Step 3: Stop the Instance

Trigger the stop command and wait for the state transition to finish.

echo "Stopping the instance..."
aws ec2 stop-instances \
    --instance-ids $INSTANCE_ID \
    --region us-east-1

aws ec2 wait instance-stopped \
    --instance-ids $INSTANCE_ID \
    --region us-east-1
echo "Instance stopped."

Step 4: Modify the Instance Type

Now that it is stopped, modify the attribute.

echo "Changing instance type to t2.nano..."
aws ec2 modify-instance-attribute \
    --instance-id $INSTANCE_ID \
    --instance-type "{\"Value\": \"t2.nano\"}" \
    --region us-east-1

Step 5: Start the Instance

Turn the instance back on and wait for it to be fully running.

echo "Starting the instance..."
aws ec2 start-instances \
    --instance-ids $INSTANCE_ID \
    --region us-east-1

aws ec2 wait instance-running \
    --instance-ids $INSTANCE_ID \
    --region us-east-1
echo "Instance is now running with the new type."

Step 6: Verification

To quickly confirm the new instance type and state:

aws ec2 describe-instances \
    --instance-ids $INSTANCE_ID \
    --query "Reservations[*].Instances[*].[InstanceId, InstanceType, State.Name]" \
    --output table \
    --region us-east-1