I responded to a GitHub issue (https://github.com/travis-ci/travis-ci/issues/10034) about this but thought it might get better visibility here.
Oftentimes I have trouble getting my projects, which use rbenv, bundler and cocoapods, to work the same way on Travis images (with rvm) as they do locally. There’s also lots of default logging for every job that costs significant time and log space.
It might be nice to have a clean OS image to work with, which we could then still cache things we want loaded on it, like Xcode, gems, brew formulas, etc. The author of the original issue mentioned setting up this kind of thing with ansible/chef (I see that Docker is not available for macOS builds (https://docs.travis-ci.com/user/docker/).
Are there security or performance concerns around something like this?