RMS is a tool for writing/running computational pipelines on a computer or across a cluster. It is more of a "cluster scripting language" than a workflow language like CWL. The bulk of the script is the bash, Python, R or Perl code that make up the steps of the pipeline, plus some extra lines to organize those steps and fill-in-the-blank "template elements" that are replaced when the script is used to generate commands.
Documentation for the tool can be found at http://rms.readthedocs.io.
The software is a pure python implementation, with no dependencies. It was developed using python 2.7, but should be compatible with 2.6+ and 3.* versions.
After installation, configuring and testing with your cluster is a little more work. Follow the instructions in http://rms.readthedocs.io/en/latest/installation.html to setup the configuration for your cluster, and run the tests in http://rms.readthedocs.io/en/latest/hello1.html to make sure it is working.