Docker 垃圾回收機制補充

時間 2020-07-20

原文原文鏈接

做者：張首富
時間：2020-07-19
w x：y18163201

咱們在以前的文章裏面講過Docker 垃圾回收機制裏面簡單的介紹了下docker * prune命令，今天咱們來詳細的解讀下最後一個docker system prune指令,解讀這個命令以前咱們先來了解下docker system dfhtml

docker system df

此參數要在 client 和 service 端的版本：1.25 版本以上才能使用docker

是作什麼的？

這個命令是輸出 Docker 在宿主機上資源的使用狀況。能夠查看鏡像佔用空間大小，容器佔用空間大小，本地的volume 和 build 緩存的大小centos

舉例使用

建立模擬環境緩存

# docker pull centos:7.6.1810
# docker pull busybox
# docker pull sellbot:20200617
# docker pull sellbot:20200614
# docker pull sellbot:20200613
# docker images
REPOSITORY                                      TAG                 IMAGE ID            CREATED             SIZE
registry.cn-hangzhou.aliyuncs.com/smb/sellbot   20200716            f363f6d1f3f5        3 days ago          544MB
registry.cn-hangzhou.aliyuncs.com/smb/sellbot   20200714            3b4aa15b779d        4 days ago          544MB
registry.cn-hangzhou.aliyuncs.com/smb/sellbot   20200713            1f7133d6f068        6 days ago          544MB
busybox                                         latest              c7c37e472d31        2 weeks ago         1.22MB
centos                                          7.6.1810            f1cb7c7d58b7        16 months ago       202MB

# docker run -id --name test centos:7.6.1810 /bin/bash -c "dd if=/dev/zero of=/tmp/1.txt bs=10000 count=2000 && sleep 300 "
# docker run -id busybox /bin/sh -c "/bin/sleep 36000"
# docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED              STATUS              PORTS               NAMES
b2fa31af4348        centos:7.6.1810     "/bin/bash -c 'dd if…"   About a minute ago   Up About a minute                       test
7bbaea0e2ded        busybox             "/bin/sh -c '/bin/sl…"   2 minutes ago        Up 2 minutes                            clever_rubin

而後使用命令查看磁盤的使用狀況,bash

# docker system df
TYPE                TOTAL               ACTIVE              SIZE                RECLAIMABLE
Images              5                   2                   797.9MB             595MB (74%)
Containers          5                   1                   20MB                20MB (100%)
Local Volumes       0                   0                   0B                  0B
Build Cache         0                   0                   0B                  0B

若是什麼參數不加這顯示數據的摘要信息，來解釋下每列的含義：網絡

1, Type: 顯示佔用磁盤空間的類型less

2, Total： 當前類型的總數量，好比在咱們這個環境一共有 5 個鏡像，ide

3, ACTIVE: 處於活動中的，當前環境中有兩個鏡像正在使用，ui

4, SIZE：當前鏡像，容器佔用磁盤的大小，spa

5，RECLAIMABLE：可回收，能夠被釋放的，百分比就是 RECLAIMABLE/SIZE 的大小。

咱們能夠查看下每一項的詳細信息

# docker system df -v
Images space usage:

REPOSITORY                                      TAG                 IMAGE ID            CREATED             SIZE                SHARED SIZE         UNIQUE SIZE         CONTAINERS
registry.cn-hangzhou.aliyuncs.com/smb/sellbot   20200716            f363f6d1f3f5        3 days ago          543.9MB             518.4MB             25.51MB             0
registry.cn-hangzhou.aliyuncs.com/smb/sellbot   20200714            3b4aa15b779d        4 days ago          543.9MB             518.4MB             25.51MB             0
registry.cn-hangzhou.aliyuncs.com/smb/sellbot   20200713            1f7133d6f068        6 days ago          543.9MB             518.4MB             25.51MB             0
busybox                                         latest              c7c37e472d31        2 weeks ago         1.224MB             0B                  1.224MB             4
centos                                          7.6.1810            f1cb7c7d58b7        16 months ago       201.8MB             0B                  201.8MB             1

Containers space usage:

CONTAINER ID        IMAGE               COMMAND                  LOCAL VOLUMES       SIZE                CREATED             STATUS                      NAMES
b2fa31af4348        centos:7.6.1810     "/bin/bash -c 'dd if…"   0                   20MB                12 minutes ago      Exited (0) 7 minutes ago    test
7bbaea0e2ded        busybox             "/bin/sh -c '/bin/sl…"   0                   0B                  12 minutes ago      Up 12 minutes               clever_rubin
ed33045b3f09        busybox             "/bin/sh -c /bin/sle…"   0                   0B                  13 minutes ago      Created                     zen_turing
fba6d39f9b6a        busybox             "/bin/sh -c /bin/sle…"   0                   0B                  13 minutes ago      Exited (1) 13 minutes ago   pensive_lederberg
6c2e7a0b4e7a        busybox             "sh"                     0                   18B                 14 minutes ago      Exited (0) 14 minutes ago   priceless_mirzakhani

Local Volumes space usage:

VOLUME NAME         LINKS               SIZE

Build cache usage: 0B

CACHE ID            CACHE TYPE          SIZE                CREATED             LAST USED           USAGE               SHARED

咱們能夠看到當咱們添加了-v選項以後就能看到更多的信息了，相信喜歡觀察的您必定發現了在 images 這一列有一個有意思的現象，就是 SIZE = SHARED SIZE + UNIQUE SIZE 咱們來分開介紹每個表格裏面每一列的含義

Images space usage:：

REPOSITORY：鏡像名稱，由倉庫地址/存放空間/鏡像名稱組成
TAG：當前一個鏡像的 tag，用來區分同一個鏡像的不一樣版本
IMAGE ID：鏡像 ID，用來區別是否爲同一個鏡像(包括版本)
CREATE：當前這個鏡像的建立時間，能夠理解爲構建時間
SIZE：當前這個鏡像的大小
SHARED SIZE：共享層的大小，咱們都知道 Docker 是分層存儲的，相同層只存儲一份
UNIQUE SIZE：區別於其餘鏡像的不一樣層的大小
CONTAINERS：當前有幾個容器是基於這個鏡像啓動的。鏡像是否能被清理依賴於這個

Containers space usage:

CONTAINER ID：容器 ID
IMAGE：容器依賴於那個鏡像啓動的
COMMAND：容器的啓動命令是什麼
LOCAL VOLUMES： VOLUME 的數量
SIZE：當前容器的大小，指的是可寫層的大小，並不包含鏡像的大小
CREATED：建立時間
STATUS：當前容器的狀態
NAMES：當前容器的名稱

Local Volumes space usage:

VOLUME NAME：卷的名稱
LINKS：
SIZE：大小

Build cache usage: 0B

在咱們這個例子裏面只有 images 和 containers 有大小，是由於咱們沒有 build 過任何鏡像，也沒有把容器的時候掛載數據卷

注意：

這個數據卷並非-v 指定的數據卷，而是咱們在構建 Dockerfile 的時候寫的 VOLUME

咱們下面來作個實驗，把 VOLUME 弄出來

FROM centos:7.6.1810
MAINTAINER zhangshoufu(wx:y18163201)
VOLUME /test/data

構建 Docker 鏡像

# docker build . -t centos:test_volume -f Dockerfile
# docker images  | grep volume
centos                                          test_volume         4c3708d6ffdd        16 seconds ago      202MB

啓動

# docker run -id --name test-volume-size -v /tmp/test:/test centos:test_volume /bin/bash -c "dd if=/dev/zero of=/test/data/1.txt bs=10000 count=2000 && sleep 300 "

查看

# docker system df -v | grep -A 3 "VOLUME NAME"
VOLUME NAME                                                        LINKS               SIZE
c72d1b4b1e06d564e6d2ecb19de0daddbfbfa322a1b7545b5b1f8b418a2ecb46   1                   20MB

到此咱們就給 Docker system df 命令講解完成了，知道這些信息，咱們自定義監控的時候就能獲取到一些特定的值，

docker system prune 刪除未使用的數據卷

它能作什麼

它能刪除全部未使用的容器，網絡，鏡像(懸空和未引用)，以及卷

不加參數使用它看看是什麼效果

# docker system prune
WARNING! This will remove:
        - all stopped containers
        - all networks not used by at least one container
        - all dangling images
        - all dangling build cache
Are you sure you want to continue? [y/N] y
Deleted Containers:
579f5e4e70638daa21e0b781bf3c394798df9bd70ceff0ba970d574961c74a4c
f9725e158430855bf5e77ec04b66f6edb7eb59c24bd122457ff7a167381e7599
b2fa31af4348519fa4cdd8270a08498b6c771ece51bc14b3caccacdfd3ad671b
ed33045b3f09eb3c245e1d49214420a8cd0e1a594a85c2323112a77d6006590c
fba6d39f9b6a022472bd9c0083972dcb220a946924be8727a94b89f1a419872c
6c2e7a0b4e7a0517970c465b4b53af8b630fe3255ddab11fa1fb2144cb540d3f

Total reclaimed space: 20MB

而後咱們 docker system df -v 看下結果

# docker system df -v
Images space usage:

REPOSITORY                                      TAG                 IMAGE ID            CREATED             SIZE                SHARED SIZE         UNIQUE SIZE         CONTAINERS
centos                                          test_volume         4c3708d6ffdd        9 minutes ago       201.8MB             201.8MB             0B                  0
registry.cn-hangzhou.aliyuncs.com/smb/sellbot   20200716            f363f6d1f3f5        3 days ago          543.9MB             518.4MB             25.51MB             0
registry.cn-hangzhou.aliyuncs.com/smb/sellbot   20200714            3b4aa15b779d        5 days ago          543.9MB             518.4MB             25.51MB             0
registry.cn-hangzhou.aliyuncs.com/smb/sellbot   20200713            1f7133d6f068        6 days ago          543.9MB             518.4MB             25.51MB             0
busybox                                         latest              c7c37e472d31        2 weeks ago         1.224MB             0B                  1.224MB             1
centos                                          7.6.1810            f1cb7c7d58b7        16 months ago       201.8MB             201.8MB             0B                  0

Containers space usage:

CONTAINER ID        IMAGE               COMMAND                  LOCAL VOLUMES       SIZE                CREATED             STATUS              NAMES
7bbaea0e2ded        busybox             "/bin/sh -c '/bin/sl…"   0                   0B                  3 hours ago         Up 3 hours          clever_rubin

Local Volumes space usage:

VOLUME NAME                                                        LINKS               SIZE
c72d1b4b1e06d564e6d2ecb19de0daddbfbfa322a1b7545b5b1f8b418a2ecb46   0                   20MB

Build cache usage: 0B

CACHE ID            CACHE TYPE          SIZE                CREATED             LAST USED           USAGE               SHARED

從上面能夠看出來他給咱們失敗的 docker，或者說中止的容器所有都清除了，釋放了容器可寫層的大小，鏡像並未刪除，

注意：

docker system prune 默認只會刪除失敗的或者中止的容器，和他們的可層，也會刪除懸空的鏡像，並不會清除全部鏡像。

咱們可使用 --filter 參數清除哪一類容器，當前支持的參數

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.

咱們可使用-a 參數清除當前機器上沒有被引用的鏡像

# 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: registry.cn-hangzhou.aliyuncs.com/smb/sellbot:20200714
untagged: registry.cn-hangzhou.aliyuncs.com/smb/sellbot@sha256:5a384898e7d11d99cefc55d9cd63518233b9751a5c4c465526cb14fff93985fd
deleted: sha256:3b4aa15b779d469887b8477b53d7cac5f4e8373ab39d0de015dec4c952ed8f87
deleted: sha256:6619936848bb2c35b219c1b2726c09fa6e8e54cb51449b6654ceeb45460236f7
untagged: registry.cn-hangzhou.aliyuncs.com/smb/sellbot:20200713
untagged: registry.cn-hangzhou.aliyuncs.com/smb/sellbot@sha256:f56d67fb69575ac79b48eb8f7a1f112966d01b6e80c1e89adaa454c8c686ca3d
deleted: sha256:1f7133d6f068499f91366eef403ed29478a9292720a3d59a8eb2f481560121aa
deleted: sha256:28044d3747ae44664b37ca14d99afe450f73e2ef05b960279f821b231a5cca6b
untagged: centos:test_volume
deleted: sha256:4c3708d6ffdd898ec25728870ad3c97bd27cbaaf9637b1b45a4e85e5a92095a9
deleted: sha256:a9d487236d0a89428a695de3a1c340c5e740bf213a35dcd9a8053025733531cc
untagged: registry.cn-hangzhou.aliyuncs.com/smb/sellbot:20200716
untagged: registry.cn-hangzhou.aliyuncs.com/smb/sellbot@sha256:b723f501cdebcee79b4d6b5b0859ce20718eded417928fa18d9f3b0135bc3ee4
deleted: sha256:f363f6d1f3f5fd25cedc0824fb33d17b5109d96a8a14a7931c7da8de812c37f6
deleted: sha256:16f95c955f85d8e1d5e6b3810e4843b9828bb0f5e215817661648b6d9c5a75b3
deleted: sha256:935e843cce2d562611a950de31beb63e17a9a1f3c3421ae3cab8db7f7ce3e1e0
deleted: sha256:bcf75aa1d1da5a81575b499af40a578888a8a7e0f813e0f516d7aefebc13690b
deleted: sha256:9ad3e1811704d30494e2d402d432c00d1d9153784a9b31cc058fffc672557606
deleted: sha256:a3473da06c6e367bb9ecb640ecac13d916568324a15ae7e8fed8f465e0690464
deleted: sha256:4a7021bd2ec6699a4c2a3c7df7ef9197b678ad56193b5b1d309a10d89532666d
deleted: sha256:6c3b476844a247d18c7eb535b9cc9d3d9f6d5063691cac5411f254b9fd7798f2
deleted: sha256:734e667e23a00543dbc5617963cb1473651316c0b1c0ba412e472960318d6e04
deleted: sha256:ffc9b21953f4cd7956cdf532a5db04ff0a2daa7475ad796f1bad58cfbaf77a07
untagged: centos:7.6.1810
untagged: centos@sha256:62d9e1c2daa91166139b51577fe4f4f6b4cc41a3a2c7fc36bd895e2a17a3e4e6
deleted: sha256:f1cb7c7d58b73eac859c395882eec49d50651244e342cd6c68a5c7809785f427
deleted: sha256:89169d87dbe2b72ba42bfbb3579c957322baca28e03a1e558076542a1c1b2b4a

Total reclaimed space: 796.7MB
[root@zhangsf docker]# docker system df
TYPE                TOTAL               ACTIVE              SIZE                RECLAIMABLE
Images              1                   1                   1.224MB             0B (0%)
Containers          1                   1                   0B                  0B
Local Volumes       1                   0                   20MB                20MB (100%)
Build Cache         0                   0                   0B                  0B

可是並不會清除 VOLUME，若是咱們想清除 VOLUME，可使用下面參數,可是不建議使用

# docker system prune -f --volumes
Deleted Volumes:
c72d1b4b1e06d564e6d2ecb19de0daddbfbfa322a1b7545b5b1f8b418a2ecb46

Total reclaimed space: 20MB

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