To install Docker on Linux SUSE, we need first to add Virtualization repository with Zypper

sudo zypper addrepo https://download.opensuse.org/repositories/Virtualization:containers/openSUSE_Leap_15.0/Virtualization:containers.repo

You have to adapt the repository url to your SUSE version. To find the correct package repository, please follow this link
https://software.opensuse.org/download.html?project=Virtualization%3Acontainers&package=docker

sudo zypper dist-upgrade
sudo zypper update
sudo zypper install docker 

Bonus, if you want to install docker-compose too

zypper install docker-compose