portfolio/labs/linux/setup/docs/docker.md

Docker

Package policy

The profile prefers Ubuntu's docker.io package. If that package is unavailable after an APT refresh, it configures Docker's official Ubuntu repository and installs Docker Engine, containerd, Buildx, and Compose plugins.

This fallback requires network access to download.docker.com.

Daemon configuration

The managed settings are:

{
  "log-driver": "json-file",
  "log-opts": {
    "max-size": "50m",
    "max-file": "5"
  }
}

Existing valid /etc/docker/daemon.json content is preserved and merged with these log settings. A changed file is backed up with a timestamp. Invalid JSON causes the profile to stop rather than overwrite operator configuration.

Log limits apply to newly created containers. Existing containers may retain their original logging configuration until recreated.

Validation

docker version
docker compose version
docker info
docker ps
docker system df
jq . /etc/docker/daemon.json

Troubleshooting and rollback

systemctl status docker
journalctl -u docker
jq empty /etc/docker/daemon.json

To restore a previous daemon configuration, review a timestamped backup, replace the current file, validate it with jq empty, and restart Docker. Do not restore blindly when workloads depend on newer daemon settings.

The profile does not configure Docker data roots, prune objects, deploy applications, or install the NVIDIA Container Toolkit.