The current Docker image for Tommy uses 2.2, not 2.5.
Ysul
$ rvm install 2.2 … Install of ruby-2.2.10 - #complete Please be aware that you just installed a ruby that requires 1 patches just to be compiled on an up to date linux system. This may have known and unaccounted for security vulnerabilities. Please consider upgrading to ruby-2.5.1 which will have all of the latest security patches.