This is just a very simple container wrapper around a command line tool. It is to avoid having to fetch a binary with, for example, wget every time during a CI/CD pipeline that natively uses containers for each job. This speeds up the process slightly and it is more efficient to "solve" this problem once in a central location.
Rancher has already made a container repository available but the images we build are very specifically tailored to function inside a CI/CD pipeline. For this reason we maintain this repository.
docker run --rm -ti perrit/rancher-cli rancher --help
docker run --rm -ti perrit/rancher-cli rancher --version
docker run --rm -ti registry.gitlab.com/perrit/rancher-cli-container rancher --help
docker run --rm -ti registry.gitlab.com/perrit/rancher-cli-container rancher --version