You need Docker to work your way through the nextflow training exercises. So a few notes beloew regarding accessibility
Help can be found here. Very useful Demo
Commands that worked for me (assuming you have Docker installed):
sudo systemctl status docker
You will get denied when you run this
docker ps -a
So add user to the docker group using the command exactly as it shows here. No need to look for your user ID
sudo usermod -aG docker ${USER}
Open a new tab and sign into aws again. The following command shoud work
docker ps -a