Ubuntu 20.04 Setup

Networking and Hostname

To assign a static IP you will need to navigate to the /etc/netplan/ directory. In there you will find your network configuration files. For this lab the configuration file was call 00-installer-config.yaml. Open the file with your preferred text editor and adjust the section for your network interface. If you don't know your network interface use ip a to show the interfaces. The configuration file should look similar to the one below. Note when editing the yaml file you can not include tabs, only spaces are allowed.

# This is the network config written by 'subiquity'
network:
  ethernets:
    ens160:
      dhcp4: false
      addresses: [10.0.5.12/24]
      gateway4: 10.0.5.2
      nameservers:
          search: [dylan.local]
          addresses: [10.0.5.5,1.1.1.1]
  version: 2

Once you finish adjusting the configuration file save and run the following command, netplan apply. This will apply the changes. Now that the network is setup it is time to adjust the hostname. To do this run hostnamectl set-hostname docker01-dylan. Then adjust the /etc/hosts file, replacing ubuntu with your new hostname. The lab document mentioned updating the cloud.cfg file. To do this navigate to /etc/cloud and edit cloud.cfg changing preserver_hostname to true.

Users and SSH

Like the other systems in the environment there will be a named sudo user. To create a new named user run useradd -md /home/dylan dylan, passwd dylan and usermod -aG sudo dylan. Note if you want bin bash to be the default shell you will either need to add -s /bin/bash to the useradd command or adjust the /etc/passwd file. Now that there is a named sudo user on the system root SSH will be disabled. Adjust /etc/ssh/sshd_config and include PermitRootLogin No. Then run systemctl restart sshd to restart SSH and apply changes.

Docker

Docker Instillation

Before installing Docker the system needs to be up to date, sudo apt update && sudo apt upgrade -y. Once the system is up to date use sudo apt install apt-transport-https ca-certificates curl software-properties-common to install the prerequisites. Then you will need to add the GPG key for the Docker Repo on your system, curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -. Then finally add the Docker repo to the APT sources sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu focal stable". Now install Docker with apt install docker-ce -y. Once Docker is installed it will automatically run, use systemctl status docker to check its status.

Docker Commands

Docker only allows commands to be run as the root user or users in the docker group. To allow non-root users to run docker commands run usermod -aG docker dylan. This will add the user to the docker group thus giving them permission to run docker commands. Running docker will present a list of commands, running docker comand --help will allow you to get the help page for that docker command. To test docker you can run docker run hellow-world. One docker command that is useful is docker ps. This command will list docker containers. By default it will only show you running Docker containers. If you use the -a flag it will show all Docker containers. Using docker run with the -d flag will run the container and instantly detach from it and have it run in the background. This is the same as --detach. The -P flag is the same as --publish-all. This flag publishes all exposed ports to random ports on the host operating system.

Docker Compose

Docker Compose allows the quick and simple management of multi-container applications. To install docker compose you will first need to download the executable, sudo curl -L "https://github.com/docker/compose/releases/download/1.28.5/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose. Then make it executable with chmod +x /usr/local/bin/docker-compose. Use docker-compose --version to ensure Docker Compose was setup correctly. To use Docker Compose you will need to create a docker-compose.yml file. An example file can be found here. This should be placed in its own project directory. From the project directory run docker-compose up -d.