基于Mert Mertce的回答，我编写了以下脚本，包括旋转器和进度条。

然而，自从写了脚本之后，我注意到我们构建服务器上的额外目录是暂时的——也就是说，Docker似乎正在清理，尽管速度很慢。我不知道如果存在删除目录的竞争，Docker是否会感到不安。我们目前的解决方案是使用documentum，但是有很多额外的开销(150+GB)。

#!/bin/bash
[[ $(id -u) -eq 0 ]] || exec sudo /bin/bash -c "$(printf '%q ' "$BASH_SOURCE" "$@")"
progname=$(basename $0)
quiet=false
no_dry_run=false
while getopts ":qn" opt
do
    case "$opt" in
      q)
          quiet=true
          ;;
      n)
          no_dry_run=true
          ;;
      ?)
          echo "unexpected option ${opt}"
          echo "usage: ${progname} [-q|--quiet]"
          echo "    -q: no output"
          echo "    -n: no dry run (will remove unused directories)"
          exit 1
          ;;
    esac
done
shift "$(($OPTIND -1))"

[[ ${quiet} = false ]] || exec /bin/bash -c "$(printf '%q ' "$BASH_SOURCE" "$@")" > /dev/null

echo "Running as: $(id -un)"

progress_bar() {
    local w=80 p=$1;  shift
    # create a string of spaces, then change them to dots
    printf -v dots "%*s" "$(( $p*$w/100 ))" ""; dots=${dots// /.};
    # print those dots on a fixed-width space plus the percentage etc.
    printf "\r\e[K|%-*s| %3d %% %s" "$w" "$dots" "$p" "$*";
}

cd /var/lib/docker/overlay2
echo cleaning in ${PWD}
i=1
spi=1
sp="/-\|"
directories=( $(find . -mindepth 1 -maxdepth 1 -type d | cut -d/ -f2) )
images=( $(docker image ls --all --format "{{.ID}}") )
total=$((${#directories[@]} * ${#images[@]}))
used=()
for d in "${directories[@]}"
do
    for id in ${images[@]}
    do
        ((++i))
        progress_bar "$(( ${i} * 100 / ${total}))" "scanning for used directories ${sp:spi++%${#sp}:1} "
        docker inspect $id | grep -q $d
        if [ $? ]
        then
            used+=("$d")
            i=$(( $i + $(( ${#images[@]} - $(( $i % ${#images[@]} )) )) ))
            break
        fi
    done
done
echo -e "\b\b " # get rid of spinner
i=1
used=($(printf '%s\n' "${used[@]}" | sort -u))
unused=( $(find . -mindepth 1 -maxdepth 1 -type d | cut -d/ -f2) )
for d in "${used[@]}"
do
    ((++i))
    progress_bar "$(( ${i} * 100 / ${#used[@]}))" "scanning for unused directories ${sp:spi++%${#sp}:1} "
    for uni in "${!unused[@]}"
    do
        if [[ ${unused[uni]} = $d ]]
        then
            unset 'unused[uni]'
            break;
        fi
    done
done
echo -e "\b\b " # get rid of spinner
if [ ${#unused[@]} -gt 0 ]
then
    [[ ${no_dry_run} = true ]] || echo "Could remove:  (to automatically remove, use the -n, "'"'"no-dry-run"'"'" flag)"
    for d in "${unused[@]}"
    do
        if [[ ${no_dry_run} = true ]]
        then
            echo "Removing $(realpath ${d})"
            rm -rf ${d}
        else
            echo " $(realpath ${d})"
        fi
    done
    echo Done
else
    echo "All directories are used, nothing to clean up."
fi

我最近遇到了一个类似的问题，overlay2变得越来越大，但我不知道是什么消耗了大量的空间。

df告诉我overlay2的大小大约是24GB。

对于du，我试图找出是什么占据了空间，但失败了。

区别来自于删除的文件(在我的情况下主要是日志文件)仍然被一个进程(Docker)使用。因此，文件不会显示du，但它占用的空间将显示df。

重新启动主机有帮助。重新启动docker容器可能已经有所帮助了…… org上的这篇文章帮助我找到了答案。

我使用了“docker system prune -a”，它清洗了卷和overlay2下的所有文件

    [root@jasontest volumes]# docker system prune -a
    WARNING! This will remove:
            - all stopped containers
            - all networks not used by at least one container
            - all images without at least one container associated to them
            - all build cache
    Are you sure you want to continue? [y/N] y
    Deleted Images:
    untagged: ubuntu:12.04
    untagged: ubuntu@sha256:18305429afa14ea462f810146ba44d4363ae76e4c8dfc38288cf73aa07485005
    deleted: sha256:5b117edd0b767986092e9f721ba2364951b0a271f53f1f41aff9dd1861c2d4fe
    deleted: sha256:8c7f3d7534c80107e3a4155989c3be30b431624c61973d142822b12b0001ece8
    deleted: sha256:969d5a4e73ab4e4b89222136eeef2b09e711653b38266ef99d4e7a1f6ea984f4
    deleted: sha256:871522beabc173098da87018264cf3e63481628c5080bd728b90f268793d9840
    deleted: sha256:f13e8e542cae571644e2f4af25668fadfe094c0854176a725ebf4fdec7dae981
    deleted: sha256:58bcc73dcf4050a4955916a0dcb7e5f9c331bf547d31e22052f1b5fa16cf63f8
    untagged: osixia/openldap:1.2.1
    untagged: osixia/openldap@sha256:6ceb347feb37d421fcabd80f73e3dc6578022d59220cab717172ea69c38582ec
    deleted: sha256:a562f6fd60c7ef2adbea30d6271af8058c859804b2f36c270055344739c06d64
    deleted: sha256:90efa8a88d923fb1723bea8f1082d4741b588f7fbcf3359f38e8583efa53827d
    deleted: sha256:8d77930b93c88d2cdfdab0880f3f0b6b8be191c23b04c61fa1a6960cbeef3fe6
    deleted: sha256:dd9f76264bf3efd36f11c6231a0e1801c80d6b4ca698cd6fa2ff66dbd44c3683
    deleted: sha256:00efc4fb5e8a8e3ce0cb0047e4c697646c88b68388221a6bd7aa697529267554
    deleted: sha256:e64e6259fd63679a3b9ac25728f250c3afe49dbe457a1a80550b7f1ccf68458a
    deleted: sha256:da7d34d626d2758a01afe816a9434e85dffbafbd96eb04b62ec69029dae9665d
    deleted: sha256:b132dace06fa7e22346de5ca1ae0c2bf9acfb49fe9dbec4290a127b80380fe5a
    deleted: sha256:d626a8ad97a1f9c1f2c4db3814751ada64f60aed927764a3f994fcd88363b659
    untagged: centos:centos7
    untagged: centos@sha256:2671f7a3eea36ce43609e9fe7435ade83094291055f1c96d9d1d1d7c0b986a5d
    deleted: sha256:ff426288ea903fcf8d91aca97460c613348f7a27195606b45f19ae91776ca23d
    deleted: sha256:e15afa4858b655f8a5da4c4a41e05b908229f6fab8543434db79207478511ff7

    Total reclaimed space: 533.3MB
    [root@jasontest volumes]# ls -alth
    total 32K
    -rw-------  1 root root  32K May 23 21:14 metadata.db
    drwx------  2 root root 4.0K May 23 21:14 .
    drwx--x--x 14 root root 4.0K May 21 20:26 ..

我有这样的问题…那是一根巨大的木头。日志如下:

/var/lib/docker/containers/<container id>/<container id>-json.log

您可以在运行命令行或撰写文件中进行管理。参见:配置日志记录驱动程序

我个人将这3行添加到我的docker-compose中。Yml文件:

my_container:
  logging:
    options:
      max-size: 10m

“官方”回答，用“修剪”命令清理，实际上不清理overlay2文件夹中的垃圾。

所以，要回答最初的问题，我们可以做的是:

免责声明:应用此功能时请小心。这可能会导致Docker对象中断!

List folder names (hashes) in overlay2 Inspect your Docker objects (images, containers, ...) that you need (A stopped container or an image currently not inside any container do not mean that you do not need them). When you inspect, you will see that it gives you the hashes that are related with your object, including overlay2's folders. Do grep against overlay2's folders Note all folders that are found with grep Now you can delete folders of overlay2 that are not referred by any Docker object that you need.

例子:

假设在overlay2目录中有这些文件夹，

a1b28095041cc0a5ded909a20fed6dbfbcc08e1968fa265bc6f3abcc835378b5
021500fad32558a613122070616963c6644c6a57b2e1ed61cb6c32787a86f048

您只有一个ID为c777cf06a6e3的图像。

然后，这样做:

docker inspect c777cf06a6e3 | grep a1b2809
docker inspect c777cf06a6e3 | grep 021500

想象一下，第一个命令找到了一些东西，而第二个命令什么也没有。

然后，您可以删除0215…overlay2文件夹:

rm -r 021500fad32558a613122070616963c6644c6a57b2e1ed61cb6c32787a86f048

回答问题的题目:

是的，如果你发现它没有被使用，直接删除overlay2文件夹是安全的。 不，如果你发现它正在被使用或者你不确定，直接删除它是不安全的。

如果你的系统也用于构建映像，你可以看看如何清理由构建器创建的垃圾，使用:

docker buildx prune --all

and

docker builder prune --all