How to remove old and unused Docker images

Question

When running Docker for a long time, there are a lot of images in system. How can I remove all unused Docker images at once safety to free up the storage?

In addition, I also want to remove images pulled months ago, which have the correct TAG.

So, I'm not asking for removing untagged images only. I'm searching for a way to remove general unused images, which includes both untagged and other images such as pulled months ago with correct TAG.

Answer 1

docker system prune -a

(You'll be asked to confirm the command. Use -f to force run, if you know what you're doing.)

Answer 2

I recently wrote a script to solve this on one of my servers:

#!/bin/bash

# Remove all the dangling images
DANGLING_IMAGES=$(docker images -qf "dangling=true")
if [[ -n $DANGLING_IMAGES ]]; then
    docker rmi "$DANGLING_IMAGES"
fi

# Get all the images currently in use
USED_IMAGES=($( \
    docker ps -a --format '{{.Image}}' | \
    sort -u | \
    uniq | \
    awk -F ':' '$2{print $1":"$2}!$2{print $1":latest"}' \
))

# Get all the images currently available
ALL_IMAGES=($( \
    docker images --format '{{.Repository}}:{{.Tag}}' | \
    sort -u \
))

# Remove the unused images
for i in "${ALL_IMAGES[@]}"; do
    UNUSED=true
    for j in "${USED_IMAGES[@]}"; do
        if [[ "$i" == "$j" ]]; then
            UNUSED=false
        fi
    done
    if [[ "$UNUSED" == true ]]; then
        docker rmi "$i"
    fi
done

Answer 3

Update Sept. 2016: Docker 1.13: PR 26108 and commit 86de7c0 introduce a few new commands to help facilitate visualizing how much space the docker daemon data is taking on disk and allowing for easily cleaning up "unneeded" excess.

docker system prune will delete ALL dangling data (i.e. In order: containers stopped, volumes without containers and images with no containers). Even unused data, with -a option.

You also have:

• docker container prune
• docker image prune
• docker network prune
• docker volume prune

For unused images, use docker image prune -a (for removing dangling and ununsed images).
Warning: 'unused' means "images not referenced by any container": be careful before using -a.

As illustrated in A L's answer, docker system prune --all will remove all unused images not just dangling ones... which can be a bit too much.

Combining docker xxx prune with the --filter option can be a great way to limit the pruning (docker SDK API 1.28 minimum, so docker 17.04+)

The currently supported filters are:

• until (<timestamp>) - only remove containers, images, and networks created before given timestamp
• label (label=<key>, label=<key>=<value>, label!=<key>, or label!=<key>=<value>) - only remove containers, images, networks, and volumes with (or without, in case label!=... is used) the specified labels.

See "Prune images" for an example.

---

Original answer (Sep. 2016)

I usually do:

docker rmi $(docker images --filter "dangling=true" -q --no-trunc)

I have an alias for removing those [dangling images]13: drmi

The dangling=true filter finds unused images

That way, any intermediate image no longer referenced by a labelled image is removed.

I do the same first for exited processes (containers)

alias drmae='docker rm $(docker ps -qa --no-trunc --filter "status=exited")'

As haridsv points out in the comments:

Technically, you should first clean up containers before cleaning up images, as this will catch more dangling images and less errors.

---

Jess Frazelle (jfrazelle) has the bashrc function:

dcleanup(){
    docker rm -v $(docker ps --filter status=exited -q 2>/dev/null) 2>/dev/null
    docker rmi $(docker images --filter dangling=true -q 2>/dev/null) 2>/dev/null
}

---

To remove old images, and not just "unreferenced-dangling" images, you can consider docker-gc:

---

A simple Docker container and image garbage collection script.

• Containers that exited more than an hour ago are removed.
• Images that don't belong to any remaining container after that are removed.

Answer 4

I'm using this command:

export BEFORE_DATETIME=$(date --date='10 weeks ago' +"%Y-%m-%dT%H:%M:%S.%NZ")
docker images -q | while read IMAGE_ID; do
    export IMAGE_CTIME=$(docker inspect --format='{{.Created}}' --type=image ${IMAGE_ID})
    if [[ "${BEFORE_DATETIME}" > "${IMAGE_CTIME}" ]]; then
        echo "Removing ${IMAGE_ID}, ${BEFORE_DATETIME} is earlier then ${IMAGE_CTIME}"
        docker rmi -f ${IMAGE_ID};
    fi;
done

This will remove all images whose creation time is greater than 10 weeks ago.

Answer 5

This worked for me:

docker rmi $(docker images | grep "^<none>" | awk "{print $3}")

Answer 6

@VonC already gave a very nice answer, but for completeness here is a little script I have been using---and which also nukes any errand Docker processes should you have some:

#!/bin/bash

imgs=$(docker images | awk '/<none>/ { print $3 }')
if [ "${imgs}" != "" ]; then
   echo docker rmi ${imgs}
   docker rmi ${imgs}
else
   echo "No images to remove"
fi

procs=$(docker ps -a -q --no-trunc)
if [ "${procs}" != "" ]; then
   echo docker rm ${procs}
   docker rm ${procs}
else
   echo "No processes to purge"
fi