docker image tag

Description

A full image name has the following format and components:

[HOST[:PORT_NUMBER]/]PATH

• HOST: The optional registry hostname specifies where the image is located. The hostname must comply with standard DNS rules, but may not contain underscores. If you don't specify a hostname, the command uses Docker's public registry at registry-1.docker.io by default. Note that docker.io is the canonical reference for Docker's public registry.
• PORT_NUMBER: If a hostname is present, it may optionally be followed by a registry port number in the format :8080.
• PATH: The path consists of slash-separated components. Each component may contain lowercase letters, digits and separators. A separator is defined as a period, one or two underscores, or one or more hyphens. A component may not start or end with a separator. While the OCI Distribution Specification supports more than two slash-separated components, most registries only support two slash-separated components. For Docker's public registry, the path format is as follows:
  • [NAMESPACE/]REPOSITORY: The first, optional component is typically a user's or an organization's namespace. The second, mandatory component is the repository name. When the namespace is not present, Docker uses library as the default namespace.

After the image name, the optional TAG is a custom, human-readable manifest identifier that's typically a specific version or variant of an image. The tag must be valid ASCII and can contain lowercase and uppercase letters, digits, underscores, periods, and hyphens. It can't start with a period or hyphen and must be no longer than 128 characters. If you don't specify a tag, the command uses latest by default.

You can group your images together using names and tags, and then push them to a registry.

Examples

Tag an image referenced by ID

To tag a local image with ID 0e5574283393 as fedora/httpd with the tag version1.0:

$ docker tag 0e5574283393 fedora/httpd:version1.0

Tag an image referenced by Name

To tag a local image httpd as fedora/httpd with the tag version1.0:

$ docker tag httpd fedora/httpd:version1.0

Note that since the tag name isn't specified, the alias is created for an existing local version httpd:latest.

Tag an image referenced by Name and Tag

To tag a local image with the name httpd and the tag test as fedora/httpd with the tag version1.0.test:

$ docker tag httpd:test fedora/httpd:version1.0.test

Tag an image for a private registry

To push an image to a private registry and not the public Docker registry you must include the registry hostname and port (if needed).

$ docker tag 0e5574283393 myregistryhost:5000/fedora/httpd:version1.0