There seems to be no simple method to do remove images from the registry as of today and looks like its a feature for registry 2.1 milestone.
One of the options what we have today with this not working
anovil@ubuntu-anovil remove-registry]$ curl -X DELETE localhost:5000/v2/alpine/manifests/v1
{"errors":[{"code":"UNSUPPORTED","message":"The operation is unsupported."}]}
[anovil@ubuntu-anovil remove-registry]$
is to manually remove it from the registry itself. Just to avoid removing wrong file accidentally, I tested it with this script from github. I take no guarantee on how this script works (though I checked it quickly before I tested it).
So, I made a test and that seems to work :)
[1] I presume that, you are running a registry with docker itself.
[anovil@ubuntu-anovil remove-registry]$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
88f8e1a1d7a7 registry:2 "/bin/registry /etc/d" 37 minutes ago Up 37 minutes 0.0.0.0:5000->5000/tcp registry
[anovil@ubuntu-anovil remove-registry]$
[2] I created a minimal Dockerfile with just FROM alpine content and created alpine:v1 and pushed to my private registry running on localhost:5000. Querying it from registry, it returned as expected.
[anovil@ubuntu-anovil remove-registry]$ curl -X GET localhost:5000/v2/alpine/tags/list
{"name":"alpine","tags":["v1"]}
[anovil@ubuntu-anovil remove-registry]$
[3] Then I log into the registry with docker exec and checked the disk usage before I do my experiment
root@88f8e1a1d7a7:/# du -sch /var/lib/registry/
2.5M /var/lib/registry/
2.5M total
root@88f8e1a1d7a7:/#
[4] After returning back to my host I copied a heavy file (mongodb.tgz) into my container and created a built and pushed version v2.
[anovil@ubuntu-anovil remove-registry]$ docker build -t localhost:5000/alpine:v2 .
Sending build context to Docker daemon 61.99 MB
Step 1 : FROM alpine
---> 2314ad3eeb90
Step 2 : COPY mongodb.tgz /mongodb.tgz
---> d7c7645a3fe2
Successfully built d7c7645a3fe2
[anovil@ubuntu-anovil remove-registry]$ docker push localhost:5000/alpine:v2
The push refers to a repository [localhost:5000/alpine] (len: 1)
d7c7645a3fe2: Pushed
5ff05309724e: Image already exists
v2: digest: sha256:7bea1ec2910170bd88412b622aee6129791673cf1fd8c0e1e34f15ec26428774 size: 4467
[anovil@ubuntu-anovil remove-registry]$
[5] After checking the size again in the registry, it has increased to 62MB:
root@88f8e1a1d7a7:/# du -sch /var/lib/registry/
62M /var/lib/registry/
62M total
root@88f8e1a1d7a7:/#
[6] In order to run delete_docker_registry_image, you need to get the script into the container which is hosting the registry, one option to do this is with curl. Also, this script requires jq.
root@88f8e1a1d7a7:/# apt-get update && apt-get install -y curl jq
...
root@88f8e1a1d7a7:/#
[7] Run the script, try with --dry-run option first and do not forget the version tag (v2 in this case), there is also a good -h
root@88f8e1a1d7a7:/# delete_docker_registry_image --image alpine:v2 --dry-run
DRY_RUN: would have deleted tag directory: repositories/alpine/_manifests/tags/v2
DRY_RUN: would have deleted manifest revision: repositories/alpine/_manifests/revisions/sha256/7bea1ec2910170bd88412b622aee6129791673cf1fd8c0e1e34f15ec26428774
DRY_RUN: would have deleted directory: blobs/sha256/e2/e2cc9aed084e01fa5cf93c09121035ac4d712113425ae68b678c28591beec5c6
DRY_RUN: would have deleted directory: blobs/sha256/7a/7ada67971e952e353ab14d8f9bdd4e41e4c41099b05a5da09f2700b51d93908a
DRY_RUN: would have deleted directory: blobs/sha256/7b/7bea1ec2910170bd88412b622aee6129791673cf1fd8c0e1e34f15ec26428774
DRY_RUN: would have deleted layer metadata directory: repositories/alpine/_layers/sha256/e2cc9aed084e01fa5cf93c09121035ac4d712113425ae68b678c28591beec5c6
root@88f8e1a1d7a7:/# delete_docker_registry_image --image alpine:v2
root@88f8e1a1d7a7:/#
[8] And voila !!
root@88f8e1a1d7a7:/# du -sch /var/lib/registry/
2.5M /var/lib/registry/
2.5M total
root@88f8e1a1d7a7:/#
Best Answer
Since docker 1.13.0 you can use the new credHelper format instead. I came here from Google having the exact same problem with credStore so thought I would add this for other to find.
Example: