Improve general docker interoperability

[torbjorn]

When setting up R in containers I repeatedly end up implementing elaborate hacks to make renv integrate seemlessly and efficiently. These are typically related to:

• where do I put the library
• handle cache efficiently
• binary incompatibilities between ubuntu packages and renv cache
• preinstall renv in the expected location during docker build
• doing restore in build or in post-build scripts?
• renv::restore never succeeds when rebuilding an image a year later

The renv project has been very forthcomming when I have asked for specific changes that makes a big difference to running renv in a container, but it's in a way a never ending story.

Perhaps a "docker task force" could be useful, a group that would maintain recomended reference implementations of renv functionality in docker based projects. They would stay informed by (or come from) core renv development and ideally advice on future renv development from a docker perspective. Things they'd maintain would typically include:

• rootless or rootfull docker
• do or do not use renv cache to speed up restore
• renv cache inside the docker context or outside of
• restore in build or post-build
• run as root or a local dockeruser
• pak - with and without
• more...

EDIT:

There is already this articlye, but in many ways it only scratches the surface of these issues:
https://rstudio.github.io/renv/articles/docker.html