Add remote tag to a docker image

The way you've stated, docker tag ...; docker push ... is the best way to add a tag to an image and share it.

In the specific example you've given, both tags were in the same repo (myregistry.com/myimage). In this case you can just docker push myregistry.com/myimage and by default the docker daemon will push all the tags for the repo at the same time, saving the iteration over layers for shared layers.

You can use the same process (docker tag ...; docker push ...) to tag images between repositories as well, e.g.

docker tag myregistry.com/myimage:v1.2.3 otherregistry.com/theirimage:v2
docker push otherregistry.com/theirimage

pull/tag/push method will have time&network costs, you can just remotely tag your image with:

only for changing TAG the answer https://stackoverflow.com/a/38362476/8430173 works , but I wanted to change the repository name too.

by many thanks to this, I changed the repoName too!

(by help of his Github project):

1- get manifests (in v2 schema)
2- post every layer.digest in the new repo
3- post config.layer
4- put whole manifest to new repo

details:

1- GET manifest from reg:5000/v2/{oldRepo}/manifests/{oldtag} withaccept header:application/vnd.docker.distribution.manifest.v2+json

2- for every layer : POST reg:5000/v2/{newRepo}/blobs/uploads/?mount={layer.digest}&from={oldRepoNameWithaoutTag}

3- POST reg:5000/v2/{newRepo}/blobs/uploads/?mount={config.digest}&from={oldRepoNameWithaoutTag}

4- PUT reg:5000/v2/{newRepo}/manifests/{newTag} with content-type header:application/vnd.docker.distribution.manifest.v2+json and body from step 1 response

5- enjoy!

You can achieve this with docker buildx imagetools create

docker buildx imagetools create myregistry.com/myimage:v1.2.3 --tag myregistry.com/myimage:staging

this will simply download the image manifest of myregistry.com/myimage:v1.2.3 and re-tag (and push) it as myregistry.com/myimage:staging

NOTE: this will also retain the multi-platform manifest list when you "re-tag" (e.g. when your image is build for both linux/arm64 and linux/amd64). Where as the conventional docker pull/push strategy will only retain the image manifest for the platform/architecture of the system you do the pull/push from.