This is a tracking ticket for increasing the minimum required Ruby version across our projects.

Requiring a minimum of Ruby 2.5 would allow us to use the following Ruby features:

Hash#transform_keys (could be very helpful for ** migration)
Speed up evergreen builds if we remove 2.4 from toolchain

Ruby branch maintenance status: https://www.ruby-lang.org/en/downloads/branches/

Presently 2.4 branch is EOL.

Ruby versions by OS:

Debian 10 (buster): 2.5
Debian 9 (stretch): 2.3
Ubuntu 18.04: 2.5
Ubuntu 16.04: 2.3
Ubuntu 14.04: ?
Centos 8: 2.5/2.6
Centos 7: 2.0