cloud init / cloud config to install Docker on Ubuntu

cloud-init.yaml

#cloud-config

# Option 1 - Full installation using cURL
package_update: true
package_upgrade: true

groups:
  - docker

system_info:
  default_user:
    groups: [ docker ]

packages:
  - apt-transport-https
  - ca-certificates
  - curl
  - gnupg
  - lsb-release
  - unattended-upgrades

runcmd:
  - mkdir -p /etc/apt/keyrings
  - curl -fsSL https://download.docker.com/linux/ubuntu/gpg | gpg --dearmor -o /etc/apt/keyrings/docker.gpg
  - echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | tee /etc/apt/sources.list.d/docker.list > /dev/null
  - apt-get update
  - apt-get install -y docker-ce docker-ce-cli containerd.io docker-compose-plugin
  - systemctl enable docker
  - systemctl start docker

final_message: "The system is finally up, after $UPTIME seconds"

simple-cloud-init.yaml

#cloud-config

# Option 2: Simplified, using the default package
package_update: true
package_upgrade: true

groups:
  - docker

system_info:
  default_user:
    groups: [docker]

packages:
  - docker.io
  - unattended-upgrades

final_message: "The system is finally up, after $UPTIME seconds"

Appreciate the comment! This is a pretty old cloud-init file, so the one I use these days has changed quite a bit, but the reason the user was explicit was to ensure that the user was added to the right group, which I believe the default user did not have.

Thanks for all the feedback over time, I've updated the script with some latest goodies, and hope that the latest form maps more closely with some of the information regarding the default_user as well as the latest recommended docker installation commands and packages (and removed the resolv_conf usage as this is probably not the best place for it right now)