How to use the command 'docker tag' (with examples)

The docker tag command is used to assign tags to existing Docker images. Tags are a way to assign a human-readable name to an image, making it easier to manage and reference. This command is especially useful when you want to version your images or give them more meaningful names.

Use case 1: Assign a name and tag to a specific image ID

Code:

docker tag id name:tag

Motivation: This use case allows you to assign a custom name and tag to a specific image ID. By assigning a name and tag, you can easily identify and manage the image in the future.

Explanation:

• id: The ID of the image you want to assign a name and tag to.
• name:tag: The desired name and tag for the image. The name can be any string, while the tag is typically a version number or a descriptive tag.

Example output:

docker tag 56f5695a9780 my-image:v1.0.0

This command assigns the name “my-image” and the tag “v1.0.0” to the image with the ID “56f5695a9780”.

Use case 2: Assign a tag to a specific image

Code:

docker tag image:current_tag image:new_tag

Motivation: In this use case, you can assign a new tag to an image with an existing tag. This is useful when you want to version your images or create different variants of the same image.

Explanation:

• image:current_tag: The name and current tag of the image you want to assign a new tag to.
• image:new_tag: The desired name and new tag for the image.

Example output:

docker tag my-image:v1.0.0 my-image:v2.0.0

This command assigns the new tag “v2.0.0” to the image “my-image” with the current tag “v1.0.0”.

Use case 3: Display help

Code:

docker tag

Motivation: This use case allows you to quickly access the help documentation for the docker tag command.

Explanation: This command has no arguments. By simply executing docker tag, Docker will display the help information, providing details on how to use the command and its available options.

Example output:

Usage:  docker tag SOURCE_IMAGE[:TAG] TARGET_IMAGE[:TAG]

Assign a name and tag to an image in the local image index

Examples:
  docker tag ubuntu:14.04 my-ubuntu:latest
  docker tag 0123456789ab my-image:latest

The output displays the usage information, along with a couple of examples demonstrating how to use the docker tag command.

Conclusion:

The docker tag command is a versatile tool for assigning tags to Docker images. It allows you to more effectively manage and reference your images by assigning them meaningful names and versions. By utilizing this command, you can improve your Docker image workflow and enhance the organization of your containerized applications.