Compare licence models, rightsize on paper, and build two identical environments from one template

Steps

1. See license-included pricing in the image itself. Look up the latest Windows Server 2022 and Amazon Linux 2023 images through their public parameters, and read how each is billed:

WIN=$(aws ssm get-parameter --name /aws/service/ami-windows-latest/Windows_Server-2022-English-Full-Base --query 'Parameter.Value' --output text)
LNX=$(aws ssm get-parameter --name /aws/service/ami-amazon-linux-latest/al2023-ami-kernel-default-x86_64 --query 'Parameter.Value' --output text)
aws ec2 describe-images --image-ids "$WIN" "$LNX" --query 'Images[].[Name,PlatformDetails,UsageOperation]' --output table

The Windows image reads Windows with a usage operation of RunInstances:0002: the Windows Server licence is part of the instance price. The Linux image reads Linux/UNIX and RunInstances, with no licence charge. A company that already owns per-core Windows licences and wanted to bring them (BYOL) would need Amazon EC2 Dedicated Hosts instead; that is lesson 23's subject, and this lab creates none. 2. Rightsize an invented server. It was moved to AWS at the same size it had on premises, a t3.small. Over three months its CPU averaged 4 percent and peaked at 11 percent, and its memory never passed 600 MiB. Compare the sizes:

aws ec2 describe-instance-types --instance-types t3.micro t3.small --query 'InstanceTypes[].[InstanceType,VCpuInfo.DefaultVCpus,MemoryInfo.SizeInMiB]' --output table

A t3.micro has the same two vCPUs and 1024 MiB of memory, enough for this workload with room to spare. Rightsizing it now, before buying any Savings Plan or Reserved Instance, avoids locking in spending on capacity it does not use. 3. Write a template that records the environment's settings. It still holds the old size, t3.small:

cat > clf-lab05-template.yaml << 'EOF'
AWSTemplateFormatVersion: '2010-09-09'
Description: clf-lab05 - the same settings for every environment
Parameters:
  EnvName:
    Type: String
    AllowedValues: [dev, test]
Resources:
  SizeParameter:
    Type: AWS::SSM::Parameter
    Properties:
      Name: !Sub '/clf-lab05/${EnvName}/instance-type'
      Type: String
      Value: t3.small
  LicenceParameter:
    Type: AWS::SSM::Parameter
    Properties:
      Name: !Sub '/clf-lab05/${EnvName}/licence-model'
      Type: String
      Value: license-included
EOF

4. Build both environments from the same file. Each deploy waits until its stack is complete:

aws cloudformation deploy --stack-name clf-lab05-dev --template-file clf-lab05-template.yaml --parameter-overrides EnvName=dev
aws cloudformation deploy --stack-name clf-lab05-test --template-file clf-lab05-template.yaml --parameter-overrides EnvName=test

5. Read both environments back and compare them:

aws ssm get-parameters-by-path --path /clf-lab05 --recursive --query 'Parameters[].[Name,Value]' --output table

Four parameters, and dev and test agree line for line. No two hand-built environments are guaranteed to do that. 6. Apply the rightsizing decision as a change to the template, then update both environments:

sed -i 's/Value: t3.small/Value: t3.micro/' clf-lab05-template.yaml
aws cloudformation deploy --stack-name clf-lab05-dev --template-file clf-lab05-template.yaml --parameter-overrides EnvName=dev
aws cloudformation deploy --stack-name clf-lab05-test --template-file clf-lab05-template.yaml --parameter-overrides EnvName=test

Notice what automation did and did not do. It made the change identical in both places and left a text file you could review. It did not lower the price of anything, and it did not make anyone other than you responsible for these resources.