computer-playbook/roles/sys-ctl-cln-docker

Cleanup Docker Resources

Description

This role performs a complete cleanup of Docker resources by invoking a systemd-managed script. It removes unused Docker images, stopped containers, networks, build cache, and anonymous volumes. The cleanup is fully automated and can run on a schedule or be triggered manually.

Overview

Optimized for maintaining a clean and efficient Docker environment, this role:

• Loads and triggers the anonymous volume cleanup role.

• Installs a systemd service and timer for Docker pruning.

• Deploys a cleanup script that invokes:

  • The anonymous volume cleanup service.
  • docker system prune -a -f to remove unused Docker resources.

• Allows forced execution during maintenance runs (MODE_CLEANUP).

Purpose

The primary purpose of this role is to prevent storage bloat caused by unused Docker images, volumes, and build artifacts. Regular pruning ensures:

• Reduced disk usage
• Improved system performance
• Faster CI/CD and container deployments
• More predictable Docker engine behavior

Features

• Anonymous Volume Cleanup: Integrates with sys-ctl-cln-anon-volumes to remove stale volumes.
• Full Docker Prune: Executes docker system prune -a -f to reclaim space.
• Systemd Integration: Registers a systemd unit and timer for automated cleanup.
• Scheduled Execution: Runs daily (or as configured) based on SYS_SCHEDULE_CLEANUP_DOCKER.
• Force Execution Mode: When MODE_CLEANUP=true, cleanup is executed immediately.
• Safe Execution: Includes validation for missing services and Docker availability.

Script Behavior

The cleanup script:

1. Checks whether the anonymous volume cleanup service is defined and available.
2. Starts the service if present.
3. Runs docker system prune -a -f if Docker is installed.
4. Stops execution immediately on errors (set -e behavior).