Installing ruby on an amazon ec2 image

sudo yum groupinstall "Development Tools"
sudo yum install postgresql-devel  # if needed
sudo yum install -y ruby24 ruby24-devel
sudo alternatives --set ruby /usr/bin/ruby2.4

If you need to install node, use nvm: https://docs.aws.amazon.com/sdk-for-javascript/v2/developer-guide/setting-up-node-on-ec2-instance.html