Hello,
The command is registry garbage-collect config.yml (It's displayed when you delete an image).

Yes you must execute this on the host (or in the container of your private registry)

I have an idea for an ENV variable on the Registry container.

• SET ENV Var for Garbage-Collect_CRON=True

This will enable garbage collection ON set to a default of every 24hrs

I would edit the code myself but I just cant find it. ;-)

Sorry, but the registry image is out of the scope of this project.
The registry image is managed by the docker team here (docker/distribution)

Thank you..

In the interim I am running on HOST:

Dry Run..

sudo docker exec ui-as-proxy_registry_1 registry garbage-collect --dry-run /etc/docker/registry/config.yml

OR - Live..

sudo docker exec ui-as-proxy_registry_1 registry garbage-collect /etc/docker/registry/config.yml

I will try to make an entrypoint file or see if CMD will run properly at end of service config in compose file..

@Joxit ,

After a delete and garbage collect the orphaned images are deleted but there is a listing in the Registry-UI that remains. When I click on it it shows no images within.

Is there a way to remove that orphaned listing from the UI as well?

No, this is a limit from docker registry, see this #53 (comment)
You can delete manually old images by deleting folders.

Here is a snippit of a Bash script I am using for garbage collection and deletion of the orphaned repo..

get_array()
{
	curl --user ${REG_USER} http://${REGISTRY}/v2/_catalog >list
    sed -i -- s#repositories##g list;
    sed -i -- s#\{##g list;
    sed -i -- s#\}##g list;
    sed -i -- s#:##g list;
    sed -i -- s#\\[##g list;
    sed -i -- s#\\]##g list;
    sed -i -- s#\"##g list;
    sed -i -- s#\"##g list;
    sed -i -- s#,#" "#g list;
	ARRAY1=$(cat list)
	garbage_collect
}

garbage_collect()
{
	docker exec ui-as-proxy_registry_1 registry garbage-collect /etc/docker/registry/config.yml	&&
	del_repo 
}

del_repo()
{  
        for i in ${ARRAY1[@]}; do 
    	curl --user ${REG_USER} http://${REGISTRY}/v2/$i/tags/list | grep null ;
      	if [ $? -eq 0 ]; then
        docker exec -it ui-as-proxy_registry_1 rm -rf /var/lib/registry/docker/registry/v2/repositories/$i
    	fi
  	done
}

Note: after deleting an image via the Repository UI the repository remains and is empty - orphaned if you will.. Creating a bash script with the snippit of code to iterate through the tags works to garbage collect and delete the orphaned repository via tags found.

To test properly I needed to restart the registry and UI containers then push the same image back into the registry container - otherwise the layer still exists for the old image somehow and would not allow me to push the image over. After restart of containers i was then able to push my image back into the registry and the UI would show the image once again...

Thank you! I hope this helps others..

//Edited for a fix...

Thanks for sharing your script.

I could not use the get_array() part so i have achieved the same with grep and substituion.
I also delete the repositoryfolder if the registry dont know the repository any more but it is still listed insed the catalog (NAME_UNKNOWN).

I leave it here if anyone want to use this:

repositories=( $(curl -s http://${REGISTRY}/v2/_catalog | grep -o '"[^"]*"') )

docker exec registry2 registry garbage-collect /etc/docker/registry/config.yml

for i in ${repositories[@]//\"/}; do
		curl -s http://${REGISTRY}/v2/${i}/tags/list | egrep '"tags":null|NAME_UNKNOWN';
		if [ $? -eq 0 ]; then
		docker exec -it registry2 rm -rf /var/lib/registry/docker/registry/v2/repositories/$i
		echo "delete empty repository $i"
		fi
done

without curl command, it's possible to check empty folder with a find -exec ls -ld. If the ls return only 2 inodes, than the folder is empty (no -empty flag for the find command of the registry image :-( )

To find all tags folder's without any tags :
find /var/lib/registry/ -type d -iname "tags" -exec ls -ld {} \;|grep "[ ][ ]2[ ]1000[ ][ ][ ][ ][ ]1000[ ]"

grep <number_of_inodes> <user_id> <group_id>. In registry container, user and group equal 1000.
Be careful about spaces in grep filter, markdown in this post trunk spaces

Extract only the image name folder with a sed, all before the time (time include) and remove subfolders /_manifests/tags
sed "s/.* [0-9][0-9]:[0-9][0-9] //;s/\/_manifests\/tags$//"

Exec find and remove folders inside the container :
docker exec registry rm -Rf $(docker exec registry find /var/lib/registry -type d -iname "tags" -exec ls -ld {} \;|grep "[ ][ ]2[ ]1000[ ][ ][ ][ ][ ]1000"|sed "s/.* [0-9][0-9]:[0-9][0-9] //;s/\/_manifests\/tags$//")

After that, perhaps some repositories haven't any images. To find theses repositories :
find /var/lib/registry/docker/registry/v2/repositories/ -type d -maxdepth 1 -mindepth 1
same grep, but for the sed, only need to remove all before the time
docker exec registry rm -Rf $(docker exec registry find /var/lib/registry/docker/registry/v2/repositories/ -type d -maxdepth 1 -mindepth 1 -exec ls -ld {} \;|grep "[ ][ ]2[ ]1000[ ][ ][ ][ ][ ]1000[ ]"|sed "s/.* [0-9][0-9]:[0-9][0-9] //")

• I have written this script

#!/bin/sh

deleted=$(registry garbage-collect /etc/docker/registry/config.yml 2>/dev/null |grep "eligible for deletion$"|cut -d' ' -f4)
if [ "$deleted" -eq 0 ];then exit;fi

cd /var/lib/registry/docker/registry/v2/repositories/
for d in $(ls -d *);do
    count=$(ls -1 $d/_manifests/tags/|wc -l)
    if [ "$count" -eq 0 ];then
       rm -fr $d
    fi
done

kill -15 1

• Save as file "cleanup.sh" within the same directory that I save docker registry data and certificates ...etc and mark as executable
• Mount that script using the -v switch like this "-v cleanup.sh:/cleanup.sh"
• Then call the cleanup script and if there any need it will restart the container like this "docker exec -it myregistry /cleanup.sh"

hope this help

hi all
thank you for your scripts for delete dangling images...
but I'm confused :(
which script is complete?

I have noticed that some problems after deleting and garbage collection are from caching in the browser. Do a full refresh of the page to get updated listings.

My process is:

1. delete the tag $tag
2. delete the tag directory in the registry directory
   rm -rf /var/lib/registry/docker/registry/v2/repositories/$name/_manifests/tags/$tag
3. run garbage collection
   registry garbage-collect /etc/docker/registry/config.yml
4. force reload of the registry ui page

@azadiali: the scripts i have found messed up my registry! I had to recover from backup more than once...

@Joxit
Hi
Did you try issue the "garbage-collect" command on host with LUA in nginx? is it possible?

Has anyone something really working ? I have tried all examples but what I run against my docker registry, the UI still shows empty repos.

did you force-reload the page? In my case the json object was cached by the browser.

As I proxy the ui via an apache I set the no-cache header and that solved the problem.

@logopk Yes I did, but my empty repo's are still there.

Can you exactly post what and how you run things at this current moment ?

Can you exactly post what and how you run things at this current moment ?

Apache (tls, proxy) > UI > registry:2.8.2

what do you mean with "exactly"?

I'm not happy with the garbage collector. It destroyed my registry more than once. So I usually backup docker volumes and return to the backup if sth. goes wrong.

@logopk the gabrage collector is not nice at all, I wondered if you used some extra script for it.

@mrashad10 nice script thanks but it doesn't work if you have registries with / in their name.

Anyway I think you could run the cleanup on the host instead of insider the container, then you have a better find.

To whom it may concern:

there is a serious bug/non-feature in the garbage collection with multi arch images. That was causing my delete issues and destroyed registry...

distribution/distribution#3178

With this in consideration, deleting in the ui and running garbage-collection on the server fixes my issues.

Does anyone know why this isn't run automatically everytime an image is deleted? It feels like it should be the default behavior to me?

Hi @littletuna4, I agree you should ask distribution/distribution
There are a lot of issues about garbage collection 😅