GUI tool for managing Docker like Kitematic

Kitematic is available for Ubuntu (although the website itself doesn't advertise it), you can get it from the Github repository.
Simply extract the downloaded file and install it with your favorite package manager.

You can try DockStation too.

It's free for personal and commercial purposes and available for Linux, macOS & Windows. There is an AppImages for Linux too.

DockStation Screenshots

If you already have docker installed, Portainer does a good job on this.
It runs in a light-weight docker container itself. It's open source and exposing a webinterface.

Just run:

docker run -d -p 9000:9000 \  
-v /var/run/docker.sock:/var/run/docker.sock \  
portainer/portainer

And point your browser to http://localhost:9000.
Check out some more background at Portainer.