The main benefit docker introduced, was leading developers to at least consider "configuration injection" and "stateless installs" ("12 factor apps"). If upstr

The main benefit docker introduced, was leading developers to at least consider "configuration injection" and "stateless installs" ("12 factor apps"). If upstream supplies a decent docker image, chances are that means the package is more amenable to scripting and running in a chroot/jail/container - and documents it dependencies somewhat. That said, snaphotting the "state" of your container/jail can be nice. Recently I used the official ruby images, and could build a custom image to use with our self-hosted gitlab (with built-in docker registry) that a) got a standard Debian based ruby image and applied updates, and b) built freetds for connecting to mssql. Now I can quickly update that base image as needed, while the CI jobs testing our rails projects "only" need a "bundle install" before running tests. And the scripts are largely reusable across heterogeneous ruby versions (yes I hope we can get all projects up on a recent ruby..).