Stolen from answer 1 - http://stackoverflow.com/questions/22415977/installing-and-managing-jenkins-on-amazon-linux
sudo yum update
sudo wget -O /etc/yum.repos.d/jenkins.repo http://pkg.jenkins-ci.org/redhat-stable/jenkins.repo
sudo rpm --import http://pkg.jenkins-ci.org/redhat-stable/jenkins-ci.org.key
sudo yum install jenkins
service jenkins start
sudo service jenkins start
sudo chkconfig jenkins on
Jenkins will be used to build/deploy ruby on rails - install Ruby on Rails as prescribed in previous post: Rails on AWS