https://yarnpkg.com/lang/en/docs/install/#centos-stable
curl --silent --location https://dl.yarnpkg.com/rpm/yarn.repo | tee /etc/yum.repos.d/yarn.repo
If you need node.js:
curl --silent --location https://rpm.nodesource.com/setup_6.x | bash - yum install nodejsyarn