Viewing and Tagging Images

=> => exporting layers 0.0s => => writing image sha256:ede8ff889a0d9bc33f7a8da0673763c887a258eb53837dd52445cdca7b7df7e3 0.0s => => naming to docker.io/library/docker-gs-ping 0.0s ``` Your exact output will vary, but provided there aren't any errors, you should see the word `FINISHED` in the first line of output. This means Docker has successfully built your image named `docker-gs-ping`. ## View local images To see the list of images you have on your local machine, you have two options. One is to use the CLI and the other is to use [Docker Desktop](/manuals/desktop/_index.md). Since you're currently working in the terminal, take a look at listing images with the CLI. To list images, run the `docker image ls`command (or the `docker images` shorthand): ```console $ docker image ls REPOSITORY TAG IMAGE ID CREATED SIZE docker-gs-ping latest 7f153fbcc0a8 2 minutes ago 1.11GB ... ``` Your exact output may vary, but you should see the `docker-gs-ping` image with the `latest` tag. Because you didn't specify a custom tag when you built your image, Docker assumed that the tag would be `latest`, which is a special value. ## Tag images An image name is made up of slash-separated name components. Name components may contain lowercase letters, digits, and separators. A separator is defined as a period, one or two underscores, or one or more dashes. A name component may not start or end with a separator. An image is made up of a manifest and a list of layers. In simple terms, a tag points to a combination of these artifacts. You can have multiple tags for the image and, in fact, most images have multiple tags. Create a second tag for the image you built and take a look at its layers. Use the `docker image tag` (or `docker tag` shorthand) command to create a new tag for your image. This command takes two arguments; the first argument is the source image, and the second is the new tag to create. The following command creates a new `docker-gs-ping:v1.0` tag for the `docker-gs-ping:latest` you built: ```console $ docker image tag docker-gs-ping:latest docker-gs-ping:v1.0 ``` The Docker `tag` command creates a new tag for the image. It doesn't create a new image. The tag points to the same image and is just another way to reference the image. Now run the `docker image ls` command again to see the updated list of local images: ```console $ docker image ls REPOSITORY TAG IMAGE ID CREATED SIZE docker-gs-ping latest 7f153fbcc0a8 6 minutes ago 1.11GB docker-gs-ping v1.0 7f153fbcc0a8 6 minutes ago 1.11GB ... ``` You can see that you have two images that start with `docker-gs-ping`. You know they're the same image because if you look at the `IMAGE ID` column, you can see that the values are the same for the two images. This value is a unique identifier Docker uses internally to identify the image. Remove the tag that you just created. To do this, you’ll use the `docker image rm` command, or the shorthand `docker rmi` (which stands for "remove image"): ```console $ docker image rm docker-gs-ping:v1.0 Untagged: docker-gs-ping:v1.0 ``` Notice that the response from Docker tells you that the image hasn't been removed but only untagged.

This section explains how to view local Docker images using the `docker image ls` command. It clarifies that not specifying a tag defaults to 'latest'. It then demonstrates how to create additional tags for an image using `docker image tag` without creating a new image and explains the composition of an image name. Finally, it shows how to remove a tag using `docker image rm`, clarifying that this only removes the tag, not the underlying image.