Connect to the instance:
chmod 400 KEYPAIR.pem
ssh -i KEYPAIR.pem ec2-user@EC2PublicIP
Install Git:
sudo yum install -y git
Setup Git Credential Helper:
git config --global credential.helper '!aws codecommit credential-helper $@'
git config --global credential.UseHttpPath true
Now you can clone the CodeCommit repo which will look something like the following:
https://git-codecommit.us-east-1.amazonaws.com/v1/repos/My-Repo