CODEWITHSUNDEEP
docker
David Z
David Z

Reputation: 7041

Docker image build ends up with dangling images

My Dockerfile:

FROM ubuntu:latest

ENV STAR_VERSION=2.7.3a
ENV DEBIAN_FRONTEND=noninteractive

RUN apt-get update \
        && apt-get install -y git-all \
        && apt-get install -y --no-install-recommends apt-utils \
        && apt-get install -y --no-install-recommends build-essential \
        && apt-get install -y make \
        && apt-get install -y libz.dev \
        && echo "downloading ${STAR_VERSION}"

WORKDIR /mnt/d/github/Docker/STAR_2.7.3a/

RUN git clone https://github.com/alexdobin/STAR.git \
        && cd STAR/source \
        && echo "making STAR ${STAR_VERSION}" \
        && make STAR

CMD ["STAR", "--version"]

Build image:

docker image build .

It showed it's successfully built (with some warnings though) but when I check it

$ docker image ls
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
<none>              <none>              e57297dc089d        29 minutes ago      1.41GB
<none>              <none>              8c4d6c6be0d2        About an hour ago   915MB
<none>              <none>              a2625623ebb7        2 hours ago         754MB
$ docker image ls --filter dangling=true
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
<none>              <none>              e57297dc089d        30 minutes ago      1.41GB
<none>              <none>              8c4d6c6be0d2        About an hour ago   915MB
<none>              <none>              a2625623ebb7        2 hours ago         754MB

Why are they all danging and no tags?

Upvotes: 2

Views: 585

Answers (1)

β.εηοιτ.βε
β.εηοιτ.βε

Reputation: 39079

Per default, the images that you build from a Dockerfile are untagged, and unamed.

You need to pass a repo:tag as option to the build command in order to tag them.

docker image build --tag some/repo:tag .

From the documentation: 

--tag , -t      Name and optionally a tag in the ‘name:tag’ format

Source: https://docs.docker.com/engine/reference/commandline/image_build/

Mind that: untagged images can also happen if you retag an another image with the same tag, so to say, stealing the tag from an existing image, leaving the old image untagged.

This will display untagged images that are the leaves of the images tree (not intermediary layers). These images occur when a new build of an image takes the repo:tag away from the image ID, leaving it as <none>:<none> or untagged. A warning will be issued if trying to remove an image when a container is presently using it. By having this flag it allows for batch cleanup.

Source: https://docs.docker.com/engine/reference/commandline/images/#filtering

Upvotes: 3

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