Every distribution on the planet handles this with chroots for doing builds and it works out just fine without needing to do gymnastics with docker. Fedora, for example, has a farm of build hosts that are architecture specific (so there is no cross-compiling outside of bootstrapping a new build target), from there a new chroot gets created for every build and the build runs isolated within it. They've been using this same system to maintain packages for up to 7 different releases at once (counting the EPEL repositories) with no issues, I fail to see any benefit docker brings to the table here - and really, nginx should just provide a stable ABI.