Removing dangling and unused images in Docker was now easy with this article. At Bobcares, with our Docker Hosting Support Services, we can handle your Docker image-related issues.

Removing dangling and unused images in Docker

Dangling Images: When we replace existing images with new ones that have the same name and tag, dangling images are produced.

Unused Images: The kind of unused images include images taken from a registry but not yet used in any containers, any image whose containers are gone, an image with an expired tag that is no longer in use, and all dangling images.

By default, the unused objects remain in Docker itself. Docker doesn’t have a mechanism to remove them. However, keeping them for a long time can result in storage space issues. In this article, we will look into some of the ways we can remove unused and dangling images in Docker.

Methods to remove unused images

1. By using the Image Name/ID: We can use the rmi command with the ID/name to remove the unused images. We can use the below code:

docker rmi imageid

docker rmi imagename

2. By using Image Prune: The docker image prune deletes all the dangling images. If the command is used along with “-a” flag, then it will remove unused images.

docker image prune -a
WARNING! This will remove all images without at least one container associated to them.
Are you sure you want to continue? [y/N] y

The list of picture IDs that were deleted together with the amount of space saved up will be returned by the command. Since we did not execute any containers, if we list the images once more, we will see that there are no images remaining.

3. By using System Prune: The docker system prune can remove containers that are not active, unused networks, dangling images, and its build cache. Similar to image prune, using “-a” flag will remove all unused containers, images, networks, and the entire build cache. This method frees up a lot of space. For e.g.,

docker system prune -a
WARNING! This will remove:
- all stopped containers
- all networks not used by at least one container
- all images without at least one container associated to them
- all build cache

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

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Conclusion

To conclude, we provide three methods from our Support team to remove the dangling and unused images in Docker.