docker tag [--help] IMAGE[:TAG] [REGISTRY_HOST/][USERNAME/]NAME[:TAG]
Assigns a new alias to an image in a registry. An alias refers to the entire image name including the optional TAG after the ':'.
If you do not specify a REGISTRY_HOST, the command uses Docker's public registry located at registry-1.docker.io by default.
Print usage statement.
The hostname of the registry if required. This may also include the port separated by a ':'
The username or other qualifying identifier for the image.
The image name.
The tag you are assigning to the image. Though this is arbitrary it is recommended to be used for a version to distinguish images with the same name. Also, for consistency tags should only include a-z0-9-_. . Note that here TAG is a part of the overall name or "tag".
Giving an image a new alias
Here is an example of aliasing an image (e.g., 0e5574283393) as "httpd" and tagging it into the "fedora" repository with "version1.0":
docker tag 0e5574283393 fedora/httpd:version1.0
Tagging an image for a private repository
To push an image to a private registry and not the central Docker registry you must tag it with the registry hostname and port (if needed).
docker tag 0e5574283393 myregistryhost:5000/fedora/httpd:version1.0
April 2014, Originally compiled by William Henry (whenry at redhat dot com) based on docker.com source material and internal work. June 2014, updated by Sven Dowideit <[email protected]> July 2014, updated by Sven Dowideit <[email protected]> April 2015, updated by Mary Anthony for v2 <[email protected]> June 2015, updated by Sally O'Malley <[email protected]>