Docker Docker Troubleshooting Cleaning Up Unused Resources docker system prune docker image prune docker container prune docker volume prune docker network prune

1. Core Command / Concept

Cleaning up unused Docker resources frees up disk space and improves system performance. docker system prune.

2. Step-by-Step

1. Check for unused resources: docker system df
2. ⚠️ Decide to prune all unused resources: docker system prune -a
3. Confirm the deletion: docker system prune -a --volumes
4. Check for unused images: docker images -a
5. ⚠️ Decide to prune all unused images: docker image prune -a
6. Confirm the deletion: docker image prune -a --force
7. Check for unused containers: docker ps -a
8. ⚠️ Decide to prune all stopped containers: docker container prune
9. Check for unused volumes: docker volume ls
10. ⚠️ Decide to prune all unused volumes: docker volume prune
11. Check for unused networks: docker network ls
12. ⚠️ Decide to prune all unused networks: docker network prune

3. Real Commands with Examples

Example 1: Prune Unused Images

Purpose: Remove unused Docker images.
Command: docker image prune -a Flags: -a removes all unused images, --force forces the deletion.

Example 2: Prune Unused Containers

Purpose: Remove stopped Docker containers.
Command: docker container prune Flags: None, but be cautious as this deletes all stopped containers.

Example 3: Prune Unused Volumes

Purpose: Remove unused Docker volumes.
Command: docker volume prune Flags: None, but be cautious as this deletes all unused volumes.

4. Common Errors

Error 1: "Error response from daemon: You cannot remove a volume that is in use"

Error message or symptom: Unable to prune a volume.
Why it happens: The volume is still in use by a container.
One-line fix: docker container stop <container_name> && docker volume prune

Error 2: "Error response from daemon: You cannot remove a network that is in use"

Error message or symptom: Unable to prune a network.
Why it happens: The network is still in use by a container.
One-line fix: docker network disconnect <network_name> <container_name> && docker network prune

Error 3: "Error response from daemon: You cannot remove an image that is being used by a container"

Error message or symptom: Unable to prune an image.
Why it happens: The image is still in use by a container.
One-line fix: docker container stop <container_name> && docker image prune -a

5. Quick Checks

Scenario 1: Check for unused images

Situation: You want to free up disk space.
Command to run: docker images -a Correct response: A list of unused images with their IDs and sizes.

Scenario 2: Check for unused containers

Situation: You want to remove stopped containers.
Command to run: docker ps -a Correct response: A list of stopped containers with their IDs and names.

Scenario 3: Check for unused volumes

Situation: You want to remove unused volumes.
Command to run: docker volume ls Correct response: A list of unused volumes with their names and sizes.

6. Last-Minute Reference

• -a flag: removes all unused resources.
• --volumes flag: includes volumes in the prune operation.
• --force flag: forces the deletion of resources.
• docker system df: displays disk usage statistics.
• docker system prune -a: removes all unused resources.
• docker image prune -a: removes all unused images.
• docker container prune: removes all stopped containers.
• docker volume prune: removes all unused volumes.
• docker network prune: removes all unused networks.
• ⚠️ Be cautious when using docker system prune -a, docker image prune -a, docker container prune, and docker volume prune as they delete resources permanently.