TLDR
Manage disk space on Debian/Ubuntu servers and Docker containers by removing unnecessary packages, cleaning up caches, and pruning Docker objects.
Context
I needed to free up space as I had a small VPS with full storage, and my notebook and desktop computers had also a really high disk usage, although I did not have that many files, but I do use a lot of docker.
After researching I did not find a guide with everything I needed (explanations included), thus here it is.
Steps
Package Manager (apt)
Remove packages that are no longer required
sudo apt-get autoremove
Clean Up APT Cache
Check the space used by the APT cache:
sudo du -sh /var/cache/apt
Clean up the APT cache:
sudo apt-get autoclean
sudo apt autoclean
Delete cache files:
sudo apt-get clean
sudo apt clean
Clear Systemd Journal Logs
Check the disk usage of systemd journal logs:
journalctl --disk-usage
Clean logs older than 3 days:
sudo journalctl --vacuum-time=3d
Docker
Docker takes a lot of space compared to vanilla servers. Check link:/slug/change-docker-data-directory-vps-optimization for a related post on the overlay2 and how to move docker data root to another volume/ drive.
Check system usage
Check overall system usage:
docker system df
For more detailed information:
docker system df -v
Use docker system prune
(from documentation)
WARNING! This will remove:
- all stopped containers
- all networks not used by at least one container
- all dangling images
- all build cache
docker system prune
Use Docker Container Prune
Warning: This will remove all stopped containers. Refer to the documentation for more details.
docker container prune # Remove all stopped containers
Use Docker Image Prune
Remove unused images (Remove all dangling images. If -a is specified, will also remove all images not referenced by any container.)
Quick note:
What are Docker Dangling Images?
- Images that have no tag and are not referenced by any container source
- Untagged layers that serve no purpose but still consume disk space.
- Not automatically removed by Docker and need to be cleaned up manually. source
docker image prune
Use docker volume prune
Remove all unused local volumes. Unused local volumes are those which are not referenced by any containers. By default, it only removes anonymous volumes.
docker volume prune # remove only anonymous (unnamed) volumes
This command removes only anonymous (unnamed) volumes by default.
To remove all unused volumes:
docker volume prune -a # remove all unused volumes
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