As long as your Docker container has persistent, mounted storage, it would work absolutely fine for basic RStudio Package Manager functionality. With a compatible host kernel, building git-based packages in a sandbox as a non-root user would work as well. For example, if you are using a modern Ubuntu host and running RStudio Package Manager in Docker, everything should work fine.
If the server is running as non-root, the critical requirement is a host operating system with a kernel that supports user namespaces. Linux kernel versions 3.8 and greater support user namespaces with no additional configuration. CentOS and RedHat 7 only support user namespaces if the feature is enabled. With older kernels, RStudio Package Manager in Docker will not work properly.
For our currently supported platforms, see the "Supported Operating Systems" section of our Platform Deprecation Strategy page. Note that older releases like RedHat 6 are supported for basic operations on hardware, but building git-based packages in a sandbox may not work in Docker without configuring RStudio Package Manager to run as `root`.
Finally, some of the sandbox operations (e.g., bind mounting) for building git-based packages require capabilities that are only available in privileged Docker processes. You must start the container with the `--privileged` option if you wish to use R process sandboxing in a Docker environment.