Resources: SSM Parameter (CW Agent JSON config), SSM Document (Command type), SSM Association targeting both instances.

Configuration:

• Custom metrics collected: mem_used_percent, disk_used_percent, swap_used_percent.
• Config stored once in SSM Parameter Store, read via amazon-cloudwatch-agent-ctl -c ssm:<param-name> - same source used by user_data at first boot and by the SSM Association for later re-application to running instances without replacement.

Issues/fixes:

• Default AWS CLI profile pointed at an unrelated AWS account; all CLI calls for this project require --profile cw-observability / AWS_PROFILE=cw-observability.

Verification: aws cloudwatch list-metrics --namespace <project_name> confirmed all three custom metrics present with correct InstanceId dimensions.