Install AWS SSM agent on CentOS 7 on Prem

Under Systems Manager go to Hybrid Activation’s and create activation
Get activation code and ID

Download ssm manager with this link replacing region names with your region

wget https://s3.us-east-2.amazonaws.com/amazon-ssm-us-east-2/latest/linux_amd64/amazon-ssm-agent.rpm

Replace the placeholder values with the Activation Code and Activation ID generated when you create a managed-instance activation, and with the identifier of the AWS Region you want to download SSM Agent from

sudo yum install -y /tmp/ssm/amazon-ssm-agent.rpm
sudo amazon-ssm-agent -register -code "activation-code" -id "activation-id" -region "region"
sudo systemctl start amazon-ssm-agent
sudo systemctl enable amazon-ssm-agent

Instance is now registered, If you want to deregister it you can use the following AWS CLI command

aws ssm deregister-managed-instance --instance-id "mi-xxxxxxxxx"

If you need to install SSM agent on Centos7 EC2 instance here are the steps.

 yum install -y https://s3.amazonaws.com/ec2-downloads-windows/SSMAgent/latest/linux_amd64/amazon-ssm-agent.rpm
systemctl status amazon-ssm-agentws.com/ec2-downloads-windows
systemctl enable amazon-ssm-agentws.com/ec2-downloads-windows