How to show all users in dockers group?

Question

How can I find out which users are in the docker group and allowed to start docker containers? (Docker 1.12.1)

Answer 1

You can use the following:

grep /etc/group -e "docker"
grep /etc/group -e "sudo"

Answer 2

Docker creates the docker group, but also any sudoers can use Docker, so you need to check two group memberships:

getent group sudo
getent group docker