If you're using a CI, you can use this image which is updated automatically
This image contains org.gnome.Sdk//3.34 & org.freedesktop.Sdk//19.08
docker.io/bilelmoussaoui/rust-nightly:latest
This image contains org.gnome.Sdk//master & org.freedesktop.Sdk//master
docker.io/bilelmoussaoui/rust-nightly:master