func (r *RepositoryService) ListTags(repo string, auth Authenticator) (TagMap, error) {
	path := fmt.Sprintf("repositories/%s/tags", repo)
	req, err := r.client.newRequest("GET", path, auth, nil)
	if err != nil {
		return nil, err
	}
	tags := TagMap{}
	_, err = r.client.do(req, &tags)
	if err != nil {
		return nil, err
	}
	return tags, nil
}
Retrieves a list of tags for the specified repository.

Docker Registry API docs: https://docs.docker.com/reference/api/registry_api/#list-repository-tags
package registry
import (
	"fmt"
)
type RepositoryService struct {
	client *Client
}
type TagMap map[string]string