Redmine & rake version: how to update for user redmine

docker rake redmine

You should install your rake and ruby via rvm under redmine user, reffer to this question on stackoverflow How to correctly install RVM in Docker?

And once you are done with RVM, re-run bundle install for Redmine.

docker rake redmine

Already installed gems can be updated by using

bundle update <gemname>

doing that also make sure you are the right user (probably redmine in your case) and in the right path (e.g. the root of your Redmine)

CodeHunter