Unable to copy docker image in JFrog Artifactory from one repo to a target repo

We have an Artifactory server to host our Docker images. I am trying to effectively re-tag one of my Docker images using the JFrog API. I know I could do this with a simple docker tag and docker push, but wanted to see how to do this more directly with the Artifactory API. Unfortunately I am running into a snag. Here's the API call I'm trying to make:

curl -X POST --user 'my@user.com:MyAPIKey' -H "Content-Type: application/json" --data \
  '{"targetRepo": "docker-local", "dockerRepository": "docker-local", "tag": "my/docker/image/original", "targetTag": "my/docker/image/new", "copy": true}' \
  https://www.myartifactoryserver.com/api/docker/docker-local/v2/promote

But this call returns the following error:

{
  "errors" : [ {
    "status" : 400,
    "message" : "'targetTag' tag value is invalid."
  } ]
}

I'm not sure what I'm doing wrong here, especially since I am able to perform this same copy using the UI. How do I do it with the API?

Solution

The problem is with the parameter values you are using for the dockerRepository, tag and targetTag parameters.
Here is an example of how to retag the image hello-world:latest (stored in the docker-local repository) as hello-world:1.0 :

POST api/docker/docker-local/v2/promote

{
  "repository" : "docker-local", // Source Artifactory repository
  "dockerRepository" : "hello-world", // Source Docker repository
  "targetRepo" : "docker-local", // Target Artifactory repository
  "tag" : "latest", // Source tag name
  "targetTag" : "1.0" // Target tag name
}

Here is an example of a curl command for sending the above request:

curl -uuser:password -XPOST -H"content-type: application/json"  -d "{\"repository\" : \"docker-local\", \"dockerRepository\" : \"hello-world\", \"targetRepo\" : \"docker-local\", \"tag\" : \"latest\", \"targetTag\" : \"1.0\"}" https://myserver.jfrog.io/artifactory/api/docker/docker-local/v2/promote

Please notice both Artifactory and Docker use the term "repository", but each uses it in a different way.
A Docker repository is a hosted collection of tagged images that, together, create the file system for a container
A Docker registry is a host that stores Docker repositories
An Artifactory repository is a hosted collection of Docker repositories, effectively, a Docker registry in every way, and one that you can access transparently with the Docker client.