Installing Docker on Ubuntu

Install

• Run this:
  

  ### Everything below can be copy/pasted as a one-liner
  . /etc/os-release && \
  sudo apt update && \
  sudo apt install -y apt-transport-https ca-certificates curl software-properties-common && \
  curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add - && \
  sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $VERSION_CODENAME stable" && \
  sudo apt update && \
  sudo apt install -y docker-ce docker-compose && \
   
  # Verify it's running
  sudo systemctl status docker
   
  # Update (create if need be) the docker configuration to use the CGNAT CIDR range for container networking
  sudo apt install -y moreutils jq && \
  sudo bash -c 'if [ ! -f "/etc/docker/daemon.json" ] ; then echo "{}" > /etc/docker/daemon.json ; fi ; jq '\''."default-address-pools"[0].base = "100.64.0.0/16" | ."default-address-pools"[0].size = 24'\'' /etc/docker/daemon.json | sponge /etc/docker/daemon.json' ; cat /etc/docker/daemon.json
   
  # Restart docker to pull in changes
  sudo systemctl restart docker
   
  # Set up cron task to clean up stale, unused docker images
  sudo bash -c 'cat << EOF > /etc/cron.daily/docker-image-prune.cron.sh
  #!/bin/bash
  ### Prune images older than 7 days
  docker image prune -af  --filter "until=$((7*24))h" 2> /dev/null > /dev/null
  EOF
  '
  sudo chmod u+x /etc/cron.daily/docker-image-prune.cron.sh

  
  

Per-admin first-time setup

For each local user you want to grant docker access (such as your own user)...

• Run this:
  

  # Add yourself to the Docker group
  sudo usermod -aG docker ${USER}
   
  # Disconnect and reconnect to apply permissions OR start a new privileged shell...
  sudo su - ${USER}

  The above only has to be run once. After that, you have persistent access every time you log in.

Optional Install of Portainer

Gives users an approachable GUI to manage containers

• Install via docker-compose
  

  sudo mkdir -p /opt/docker-compose/portainer
  cd /opt/docker-compose/portainer
  sudo vi docker-compose.yaml