Docker is a powerful containerization platform that allows developers to create, deploy, and manage applications efficiently. When working with Docker, it’s common to need to rename images or repositories for organization, versioning, or deployment purposes. In this tutorial, we’ll explore how to rename Docker images and repositories using the docker tag and docker rmi commands.
Understanding Docker Image Names
A Docker image name consists of three parts: the repository name, the image name, and the tag. The repository name is optional and defaults to the Docker Hub username or a custom registry URL. The image name is required and identifies the specific image, while the tag is used for versioning.
For example, in the image name myname/server:latest, myname is the repository name, server is the image name, and latest is the tag.
Renaming a Docker Image
To rename a Docker image, you can use the docker tag command. This command creates a new alias for an existing image. The basic syntax is:
docker tag CURRENT_IMAGE_NAME NEW_IMAGE_NAME
Here, CURRENT_IMAGE_NAME is the current name of the image, and NEW_IMAGE_NAME is the desired new name.
For example, to rename an image from server:latest to myname/server:latest, you would run:
docker tag server:latest myname/server:latest
You can also use the image ID instead of the current image name:
docker tag d583c3ac45fd myname/server:latest
Note that the docker tag command only creates a new alias and does not modify the original image.
Removing Old Image Names
After renaming an image, you may want to remove the old image name. You can do this using the docker rmi command:
docker rmi OLD_IMAGE_NAME
This will remove the old image name from your local Docker repository. However, it will not delete the underlying image data, as long as there are other references to the same image.
Example Use Cases
Here are some example use cases for renaming Docker images:
- Versioning: You can rename an image to reflect a new version or release.
docker tag myapp:latest myapp:v2
- Repository migration: You can rename an image to move it from one repository to another.
docker tag docker.mycompany.com/myapp mynewregistry.com/myapp
- ECR and Amazon: When using Amazon’s ECR, you may need to assign the full ARN as the tag.
aws ecr create-repository --repository-name myFavoriteTag --image-scanning-configuration scanOnPush=true --region myFavoriteRegion
docker tag myFavoriteTag:latest aws_account_id.dkr.ecr.aws_region.amazonaws.com/myFavoriteTag:latest
Best Practices
When renaming Docker images, keep the following best practices in mind:
- Use meaningful and descriptive image names to help with organization and identification.
- Avoid using generic or default image names, such as
latest, without specifying a version or tag. - Keep track of your image versions and tags to ensure consistency and reproducibility.
By following these guidelines and using the docker tag and docker rmi commands effectively, you can efficiently manage your Docker images and repositories.