I am using SSM Parameter Store for config management. There, I have one GENERAL config that is used by all EC2 instances. Additionally, I have SPECIFIC config for EC2 instances that require more setting beyond the GENERAL config.

Here is how you could do it:

#fetch GENERAL config from the SSM parameter store:

sudo /opt/aws/amazon-cloudwatch-agent/bin/amazon-cloudwatch-agent-ctl -a fetch-config -s -m ec2 -c ssm:AmazonCloudWatch-GENERAL-cw-config

#fetch SPECIFIC config from the SSM parameter store:

sudo /opt/aws/amazon-cloudwatch-agent/bin/amazon-cloudwatch-agent-ctl -a append-config -m ec2 -s -c ssm:AmazonCloudWatch-SPECIFIC-cw-config