How does PyTorch build to support various Linux distributions

PyTorch is supported on Linux distributions that use glibc >= v2.17. I am wondering how PyTorch achieve this? How does Pytorch library build? Is it built upon various base docker images of various Linux distributions with minimum version? Or it’s built upon a universal image such as UBI8?

The PyTorch binaries are built in a CentOS7 image providing glibc2.17.

The default gcc version on CentOS7 is 7.3, so we need to upgrade it to gcc 9 manually for torch build?