$ \curl -sSL https://get.rvm.io | bash -s stable
OR
https://www.ruby-lang.org/en/installation/
With yum:
$ yum install redis
OR
From source (example below):
$ wget http://download.redis.io/releases/redis-2.8.13.tar.gz
$ tar xzf redis-2.8.13.tar.gz
$ cd redis-2.8.13
$ make
$ yum install postgres