> why we don't see ruby used for shell stuff more often
Simple, ruby is not installed by default. Even Python, while it is on (almost?) all modern Linux distributions, is not installed on the BSDs.
Simple, ruby is not installed by default. Even Python, while it is on (almost?) all modern Linux distributions, is not installed on the BSDs.
Alpine for example doesn't ship Bash. Mac OS ships Ruby and its Bash is quite old.
Installing python and other general purpose tools gives any attacker that gets into a docker container many more tools to work with for getting out.
For docker, the trend isn't "build a general purpose machine" but rather "what can we slim this down to that only has the bare minimum in it?" This can be taken all the way to the distroless images ( https://github.com/GoogleContainerTools/distroless ) and means that the security team won't be asking you to fix that CVE that's in Python that you don't use.
If, however, you do need python in an image because that image's purpose is to do some python, then you can pull a python image that has the proper release.