Docker uses the host operating system kernel, there is no custom or additional kernel inside the container. All containers running on the machine are sharing this “host” kernel. See for more information this question on SuperUser.
The uname command is pulling specs from the kernel running on the host. If I enter a Ubuntu container on my Debian host, the uname will answer with a Debian build of the kernel. To know the version of Ubuntu you are running, do a $ cat /etc/lsb-release DISTRIB_ID=Ubuntu DISTRIB_RELEASE=16.04 DISTRIB_CODENAME=xenial DISTRIB_DESCRIPTION=”Ubuntu 16.04.3 LTS” It’s … Read more