在上面的评论中，人们建议修剪系统，如清除悬空卷，图像，退出容器等，有时你的应用程序成为罪魁祸首，它在很短的时间内产生了太多的日志，如果你使用一个空的目录卷(本地卷)，这会填满/var分区。在这种情况下，我发现下面的命令非常有趣，要弄清楚是什么在消耗我的/var分区磁盘上的空间。

du -ahx /var/lib | sort -rh | head -n 30

This command will list top 30, which is consuming most space on a single disk. Means if you are using external storage with your containers, it consumes a lot of time to run du command. This command will not count mount volumes. And is much faster. You will get the exact directories/files which are consuming space. Then you can go to those directories and check which files are useful or not. if these files are required then you can move them to some persistent storage by making change in app to use persistent storage for that location or change location of that files. And for rest you can clear them.

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 ..

Docker使用/var/lib/docker来存储映像、容器和本地命名卷。删除它可能导致数据丢失，并可能停止引擎运行。overlay2子目录专门包含图像和容器的各种文件系统层。

要清除未使用的容器和映像，请参阅docker系统修剪。还有一些选项可以删除卷，甚至是带标签的图像，但默认情况下由于数据丢失的可能性而不启用:

$ docker system prune --help

Usage:  docker system prune [OPTIONS]

Remove unused data

Options:
  -a, --all             Remove all unused images not just dangling ones
      --filter filter   Provide filter values (e.g. 'label=<key>=<value>')
  -f, --force           Do not prompt for confirmation
      --volumes         Prune volumes

剪枝永远不会删除的内容包括:

正在运行的容器(使用docker ps列出它们) 这些容器上的日志(有关限制日志大小的详细信息，请参阅这篇文章) 由这些容器所做的文件系统更改(通过docker diff可见)

此外，在这个垃圾收集过程中，docker可能不会看到在普通docker文件夹之外创建的任何内容。这可能是其他应用写到这个目录，或者docker引擎之前的配置(例如，从AUFS切换到overlay2，或者可能在启用用户名称空间之后)。

What would happen if this advice is ignored and you deleted a single folder like overlay2 out from this filesystem? The container filesystems are assembled from a collection of filesystem layers, and the overlay2 folder is where docker is performing some of these mounts (you'll see them in the output of mount when a container is running). Deleting some of these when they are in use would delete chunks of the filesystem out from a running container, and likely break the ability to start a new container from an impacted image. See this question for one of many possible results.

为了完全刷新docker到一个干净的状态，你可以删除整个目录，而不仅仅是像overlay2这样的子目录:

# danger, read the entire text around this code before running
# you will lose data
sudo -s
systemctl stop docker
rm -rf /var/lib/docker
systemctl start docker
exit

引擎将在完全空的状态下重新启动，这意味着你将失去所有:

图片 容器 名叫卷 用户创建的网络 群状态

背景

The blame for the issue can be split between our misconfiguration of container volumes, and a problem with docker leaking (failing to release) temporary data written to these volumes. We should be mapping (either to host folders or other persistent storage claims) all of out container's temporary / logs / scratch folders where our apps write frequently and/or heavily. Docker does not take responsibility for the cleanup of all automatically created so-called EmptyDirs located by default in /var/lib/docker/overlay2/*/diff/*. Contents of these "non-persistent" folders should be purged automatically by docker after container is stopped, but apparently are not (they may be even impossible to purge from the host side if the container is still running - and it can be running for months at a time).

解决方案

解决方案需要仔细的手动清理，虽然已经在其他地方描述过，但您仍然可以从我的案例研究中找到一些提示，我试图使其尽可能具有启发性和普遍性。

所以发生的事情是罪魁祸首应用程序(在我的案例中是claire -scanner)设法在几个月内向docker的overlay2的/diff/tmp子文件夹写入了数百gb的数据

du -sch /var/lib/docker/overlay2/<long random folder name seen as bloated in df -haT>/diff/tmp

271G total

因此，由于/diff/tmp中的所有子文件夹都是相当自解释的(都是克莱尔-scanner-*的形式，并且有过时的创建日期)，我停止了相关的容器(docker stop clair)，并小心地从diff/tmp中删除了这些过时的子文件夹，谨慎地从一个(最古老的)单一文件夹开始，并测试了对docker引擎的影响(这需要重新启动[systemctl restart docker]来回收磁盘空间):

rm -rf $(ls -at /var/lib/docker/overlay2/<long random folder name seen as bloated in df -haT>/diff/tmp | grep clair-scanner | tail -1)

我回收了数百gb的磁盘空间，而不需要重新安装docker或清除它的整个文件夹。所有正在运行的容器都必须在某一时刻停止，因为需要重新启动docker守护进程来回收磁盘空间，因此首先要确保您的故障转移容器在某个/其他节点上正确运行。我希望docker的prune命令也能覆盖过时的/diff/tmp(甚至/diff/*)数据(通过另一个开关)。

这是一个有3年历史的问题，你可以在Docker论坛上阅读它丰富多彩的历史，其中针对上述解决方案的应用程序日志的变体在2019年被提出，并且似乎在几个设置中起了作用:https://forums.docker.com/t/some-way-to-clean-up-identify-contents-of-var-lib-docker-overlay/30604

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

我也有同样的问题，在我的实例中，这是因为' var/lib/docker '目录被挂载到一个运行的容器(在我的情况下谷歌/cadvisor)，因此它阻止了docker修剪清理文件夹。停止容器，运行docker prune -然后重新运行容器解决了问题。