Sunday 9 June 2019

Tagging a docker image

In this article we will see how to tag an image in docker.

Docker Image Tag background

Tagging an image gives docker image a version to refer from local repository or docker hub. Though optional, it is highly recommended to have a tag for an image. If you look at the docker image its naming looks like: username/repository:tag

Different ways to tag a docker image
Different ways to tag a docker image

Command to tag an image

There are multiple ways we can tag a docker image. Here are the ways to tag a docker image:

(a) Tagging an image during image creation: 

We can create a tag or multiple tags during image creation. The only limitation is that the docker version should be 1.10 or above. The command is:

docker build -t name1:tag1 -t name2:tag2 -t name2:tag3

(b) Tagging an image using image:

Using tag command, we can tag an existing image. There are 2 ways to do that. Using image id or using image name

docker tag myimage tech693/myimage:1.0

This will create another copy of image with name "tech693/myimage" with tag "1.0"

Deleting a docker Image

So well you have created image but now want to delete it. docker rmi command is used to delete the image

docker rmi <imagename:tag>

How to rename docker image

Renaming docker image is easy but bit tricky. The idea here is to create another image with tag and delete the older one.


docker tag <oldImage:tag> <newImage:tag>
docker rmi <oldImage:tag>

You will notice that if you tag same docker image with multiple name, its Image id remains same which mean tagging is just a name to refer the Image Id for human readability purpose.

That's all about tagging a docker image. If you have query, please ask in comment section. Thanks

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