Docker: No Space Left on Device

Fix Docker disk space issues, clean unused images, containers, volumes and build cache to free up space

Docker accumulates unused images, containers, volumes, and build cache over time. This guide shows you how to diagnose and free up disk space.

Diagnose Disk Space Issues

Check Partition Usage

df -h

Sample output:

Filesystem      Size  Used Avail Use%  Mounted on
/dev/sda1        50G   48G  1.5G  97%  /

Check Docker Disk Usage

docker system df

Sample output:

TYPE            TOTAL     ACTIVE    SIZE      RECLAIMABLE
Images          15        4         8.5GB     7.2GB (84%)
Containers      12        2         2.3GB     2.1GB (90%)
Local Volumes   8         3         1.8GB     1.5GB (83%)
Build Cache     24        0         3.2GB     3.2GB (100%)

Quick Complete Cleanup

Clean all unused Docker resources at once:

# WARNING: Removes ALL unused images, containers, volumes, and build cache
sudo docker system prune -a --volumes

Sample output:

WARNING! This will remove:
  - all stopped containers
  - all networks not used by at least one container
  - all unused images
  - all unused volumes

Are you sure you want to continue? [y/N] y

Deleted Containers: 8
Deleted Images: 12
Deleted Volumes: 5
Deleted Build Cache: 24

Total reclaimed space: 14.5GB

docker system prune -a removes ALL unused images, including those needed to restart stopped containers. Ensure you have docker-compose.yml files to recreate them if needed.

Selective Cleanup

Remove Stopped Containers Only

docker container prune

# Without confirmation
docker container prune -f

Remove Unused Images

# Only dangling images (orphaned)
docker image prune

# All unused images (not used by any container)
docker image prune -a

# Remove images without confirmation
docker image prune -a -f

Remove Unused Volumes

docker volume prune

# Without confirmation
docker volume prune -f

Remove Build Cache

docker builder prune

# All build cache (even recent)
docker builder prune -a

# Without confirmation
docker builder prune -a -f

Container Log Rotation

Container logs can grow to gigabytes. Configure automatic log rotation.

Check Log Size

# Find which container has large logs
docker inspect <container_id> --format='{{.LogPath}}'

# Check size
du -h /var/lib/docker/containers/<container_id>/*-json.log

Truncate Large Logs

# Clear logs for a container
sudo truncate -s 0 /var/lib/docker/containers/<container_id>/*-json.log

Enable Log Rotation in Docker Daemon

Edit /etc/docker/daemon.json:

{
  "log-driver": "json-file",
  "log-opts": {
    "max-size": "10m",
    "max-file": "3",
    "labels": "production_status=true"
  }
}

Restart Docker:

sudo systemctl restart docker

This keeps each log file max 10MB, keeps 3 files per container (30MB total).

Identify Large Images

# List all images with sizes
docker images --format "table {{.Repository}}\t{{.Tag}}\t{{.Size}}"

# Find largest images
docker images --format "table {{.Repository}}\t{{.Tag}}\t{{.Size}}" | sort -k3 -h -r | head -10

Remove Specific Image

docker image rm image_name:tag

# Force remove (even if in use)
docker image rm -f image_name:tag

Move Docker to Larger Partition

If your root partition is full and you have another disk:

Edit Docker Daemon Configuration

Edit /etc/docker/daemon.json:

{
  "data-root": "/mnt/large-disk/docker"
}

Move Existing Data

# Stop Docker
sudo systemctl stop docker

# Create new directory
sudo mkdir -p /mnt/large-disk/docker

# Copy existing data (preserves permissions)
sudo rsync -av /var/lib/docker/ /mnt/large-disk/docker/

# Start Docker
sudo systemctl start docker

# Verify
docker system df

# Remove old data (after verification)
sudo rm -rf /var/lib/docker

Automated Weekly Cleanup

Schedule automatic cleanup with crontab:

sudo crontab -e

Add:

# Clean Docker every Sunday at 2 AM
0 2 * * 0 /usr/bin/docker system prune -a --volumes -f

Verify:

sudo crontab -l

Analyze Disk Usage in Detail

Use ncdu for interactive disk usage inspection:

sudo apt install ncdu

# Analyze Docker directory
sudo ncdu /var/lib/docker

Navigate with arrow keys, press 'd' to delete, 'q' to quit.

Troubleshooting Checklist

Check available space: df -h
View Docker usage: docker system df
List largest images: docker images --format "table {{.Repository}}\t{{.Size}}" | sort -k2 -h -r
Remove unused images: docker image prune -a -f
Remove unused volumes: docker volume prune -f
Clean build cache: docker builder prune -a -f
Check container logs: docker inspect <container> --format='{{.LogPath}}'
Enable log rotation in /etc/docker/daemon.json
Verify space freed: docker system df

Recovery: Restore from Backup

If Docker data was accidentally deleted, restore from backup:

# Stop Docker
sudo systemctl stop docker

# Restore data
sudo rsync -av /backup/docker/ /var/lib/docker/

# Start Docker
sudo systemctl start docker

# Verify containers and volumes
docker ps -a
docker volume ls

Docker: No Space Left on Device

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