change docker image tag systematically

Question

In my system there are multiple images of some app that I created. All of the images I want to address have latest tag (there might be other images with other tags).

$ docker images
REPOSITORY         TAG         IMAGE ID        CREATED            SIZE
image1             latest      abcdefg1        5 minutes ago      1.00GB
and-image2         latest      abcdefg2        6 minutes ago      2.00GB
might-have-img3    latest      abcdefg3        7 minutes ago      2.50GB

How can I change all images with this tag to another tag? (as you notice, repository name is not uniform, so grep on repository might not help)

Answer 1

Here's a way I found that works for me, for whoever needs it for future:

docker images | grep latest | awk '{print "docker tag " $1 ":" $2 " " $1 ":my_new_tag"}' | xargs -L1 -I %s -- sh -c %s

Brief command explanation

The command gets a list of all images, then greps over those with the wanted tag. On each item in the list, we format it like this:

docker tag repository_fullname:latest repository_fullname:new_tag

Then each item is executed as a shell command. So it actually does the following:

$ docker tag image1:latest image1:new_tag
$ docker tag and-image2:latest and-image2:new_tag
$ docker tag might-have-img3:latest might-have-img3:new_tag