Docker Certified Associate Exam Course
Docker Image Management
Removing a Docker Image
Cleaning up unused Docker images helps reclaim disk space and keep your environment tidy. Before deleting an image, ensure no containers are running from it. Stop and remove any dependent containers first.
Note
You cannot remove an image if there are existing containers based on it. Always run docker container ls -a
and docker container rm <container_id>
as needed.
1. List All Images
To view all images on your host:
docker image ls
Example output:
REPOSITORY TAG IMAGE ID CREATED SIZE
httpd alpine 52862a02e4e9 2 weeks ago 112MB
httpd customv1 52862a02e4e9 2 weeks ago 112MB
httpd latest c2aa7e16edd8 2 weeks ago 165MB
ubuntu latest 549b9b86cb8d 4 weeks ago 64.2MB
In this example, the image ID 52862a02e4e9
has two tags: httpd:alpine
and httpd:customv1
.
2. Remove a Single Tag
When you run docker image rm <repository>:<tag>
, Docker:
- Removes the tag (soft link).
- Deletes the image layers only if no other tags reference them.
Remove the customv1
tag:
docker image rm httpd:customv1
Output:
Untagged: httpd:customv1
Since httpd:alpine
still points to the same layers, only the tag is removed.
Verify the remaining images:
docker image ls
Result:
REPOSITORY TAG IMAGE ID CREATED SIZE
httpd alpine 52862a02e4e9 2 weeks ago 112MB
httpd latest c2aa7e16edd8 2 weeks ago 165MB
ubuntu latest 549b9b86cb8d 4 weeks ago 64.2MB
Removing the last tag deletes the layers and reclaims space:
docker image rm httpd:alpine
Output:
Untagged: httpd:alpine
Deleted: sha256:52862a02e4e9...
Deleted: sha256:...
Total reclaimed space: 112MB
3. Prune All Unused Images
If you have many dangling or unreferenced images, use:
docker image prune -a
Warning
This command deletes all images not currently used by at least one container. Use with caution in production.
You will be prompted to confirm:
WARNING! This will remove all images without at least one container associated to them.
Are you sure you want to continue? [y/N] y
Sample output:
Deleted Images:
untagged: ubuntu:latest
deleted: sha256:549b9b86c8d75a2668c21c50ee927...
untagged: httpd:latest
deleted: sha256:c2aa7e16d855da8827aa0ccf9761...
Total reclaimed space: 229.4MB
Common Docker Image Removal Commands
Command | Description |
---|---|
docker image ls | List all images |
docker image rm <repository>:<tag> | Remove a specific image tag (and layers if orphan) |
docker image prune | Delete dangling images (untagged) |
docker image prune -a | Delete all unused images |
docker container ls -a | List all containers (to identify dependencies) |
docker container rm <container_id> | Remove specified container |
Links and References
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