Like many companies, Google uses a variety of operating systems
in-house. macOS and Windows are used by a large number of employees, a
modified build of Debian Linux is used on its servers (as of 2014,
at least), and Chrome OS and Android devices are commonplace. In work
environments where Linux is needed, Google uses a customized version of Ubuntu 14.04 called 'Goobuntu,' which has never been released publicly.
At DebConf in August 2017 (the news didn't catch media attention
until now), Google announced that it would switch from Goobuntu to a
Debian-based distribution called 'gLinux.' It's based on the upcoming
Debian 10 release, and the company has developed a tool for migrating
systems from Goobuntu to gLinux.
Google's shift in its preferred Linux distribution is important for
two reasons. Firstly, Google will now contribute to the Debian Project
instead of Ubuntu, which benefits anyone wanting to use Debian on their
own computers. Secondly, Canonical (the company behind Ubuntu) is likely
losing one of its largest customers, but it hasn't disclosed details
about lost revenue.
gLinux will probably never see a public release, like its predecessor
Goobuntu, but it's still interesting to see what the world's top
companies use internally.
Source: https://www.androidpolice.com/2018/01/19/googles-linux-workstations-switching-ubuntu-debian/