Docker-解決空間不足的問題以及修改預設配置

摘要： 問題 dpkg: error processing archive /var/cache/apt/archives/libc6-dev-i386_2.23-0ubuntu10_amd64.deb (--unpack): cannot copy extracted data for ...

問題

dpkg: error processing archive /var/cache/apt/archives/libc6-dev-i386_2.23-0ubuntu10_amd64.deb (--unpack):
 cannot copy extracted data for './usr/lib32/libresolv.a' to '/usr/lib32/libresolv.a.dpkg-new': failed to write (No space left on device)

Google了一圈之後，大多人的解決方案是刪除所有不用的VOLUME、容器以及映象等等。本質上只是騰出位置而已。但是如果業務需要所有的這些東西必不可刪除的的話。這個問題還是無解。

定位問題

• 檢視磁碟資訊

pi@raspberrypi:~$ df -lh
FilesystemSizeUsed Avail Use% Mounted on
udev32G032G0% /dev
tmpfs6.3G599M5.8G10% /run
/dev/mapper/vg00-root19G1.7G17G10% /
tmpfs32G032G0% /dev/shm
tmpfs5.0M05.0M0% /run/lock
tmpfs32G032G0% /sys/fs/cgroup
/dev/sda1180M54M113M33% /boot
/dev/mapper/vg00-tmp945M56M825M7% /tmp
/dev/mapper/vg00-var3.7G3.1G462M88% /var
/dev/mapper/vg00-data1.6T631G882G42% /data
tmpfs6.3G06.3G0% /run/user/25439

我是在/data分割槽上面掛載的VOLUME。一開始以為是硬碟儲存不夠導致的問題，後來發現不是這個問題(很明顯我的空間剩餘非常大)。

再想，其實這個是映象內部在下載依賴的時候導致的空間不足，並沒有對VOLUME進行任何IO操作。也就是說應當是docker本身的映象/容器掛載點出現了問題。

• 檢視 docker資訊

pi@raspberrypi:~$ docker info
Containers: 2
 Running: 0
 Paused: 0
 Stopped: 2
Images: 3
Server Version: 18.09.1
Storage Driver: overlay2
 Backing Filesystem: extfs
 Supports d_type: true
 Native Overlay Diff: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
 Volume: local
 Network: bridge host macvlan null overlay
 Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog
Swarm: inactive
Runtimes: runc
Default Runtime: runc
Init Binary: docker-init
containerd version: 9754871865f7fe2f4e74d43e2fc7ccd237edcbce
runc version: 96ec2177ae841256168fcf76954f7177af9446eb
init version: fec3683
Security Options:
 apparmor
 seccomp
Profile: default
Kernel Version: 4.4.0-87-generic
Operating System: Ubuntu 16.04.5 LTS
OSType: linux
Architecture: x86_64
CPUs: 24
Total Memory: 62.89GiB
Name: raspberrypi
ID: 2MO2:4Z6P:X2RQ:RPW7:PGWL:AJXZ:NX7M:66FR:GSUH:5PBC:2QFK:WH4O
Docker Root Dir: /var/lib/docker
Debug Mode (client): false
Debug Mode (server): false
Registry: https://index.docker.io/v1/
Labels:
Experimental: false
Insecure Registries:
 127.0.0.0/8
Live Restore Enabled: false
Product License: Community Engine

WARNING: No swap limit support

注意上面的一句Docker Root Dir: /var/lib/docker , 這應該是跟Docker儲存映象等有關。於是做了幾個小實驗：刪除和建立容器/映象並觀察/var 分割槽。發現此分割槽同步改變體積，於是我的思路就是修改Docker Root Dir 。後來問詢得知可以通過修改DOCKER_OPTS (新增-g /xxx)可以修改掛載點。

修改 /etc/default/docker

pi@raspberrypi:~$ dosu ls -l /etc/default/docker
-rw-r--r-- 1 root root 685 Jan 18 10:49 /etc/default/docker
pi@raspberrypi:~$ dosu cat /etc/default/docker
# Docker Upstart and SysVinit configuration file

#
# THIS FILE DOES NOT APPLY TO SYSTEMD
#
#Please see the documentation for "systemd drop-ins":
#https://docs.docker.com/engine/admin/systemd/
#

# Customize location of Docker binary (especially for development testing).
#DOCKERD="/usr/local/bin/dockerd"

# Use DOCKER_OPTS to modify the daemon startup options.
#DOCKER_OPTS="--dns 8.8.8.8 --dns 8.8.4.4"
# 新增路徑
DOCKER_OPTS="-g /data/docker/"

# If you need Docker to use an HTTP proxy, it can also be specified here.
#export http_proxy="http://127.0.0.1:3128/"

# This is also a handy place to tweak where Docker's temporary files go.
#export DOCKER_TMPDIR="/mnt/bigdrive/docker-tmp"
pi@raspberrypi:~$

重啟

sudo service docker restart

操作。不管用。

後於https://github.com/moby/moby/issues/9889#issuecomment-109778351 發現這種修改是有限制的。

Correct, the /etc/default/docker file is only used on systems using “upstart” and “SysVInit”, not on systems using systemd.
This is also mentioned at the top of the file; https://github.com/docker/docker/blob/44fe8cbbd174b5d85d4a063ed270f6b9d2279b70/contrib/init/sysvinit-debian/docker.default#L1

修改 /lib/systemd/system/docker.service

pi@raspberrypi:~/docker-config$ dosu cat /lib/systemd/system/docker.service
[Unit]
Description=Docker Application Container Engine
Documentation=https://docs.docker.com
BindsTo=containerd.service
After=network-online.target firewalld.service
Wants=network-online.target
Requires=docker.socket

[Service]
Type=notify
# the default is not to use systemd for cgroups because the delegate issues still
# exists and systemd currently does not support the cgroup feature set required
# for containers run by docker
ExecStart=/usr/bin/dockerd -g /data/docker/ -H fd://
ExecReload=/bin/kill -s HUP $MAINPID
TimeoutSec=0
RestartSec=2
Restart=always

# Note that StartLimit* options were moved from "Service" to "Unit" in systemd 229.
# Both the old, and new location are accepted by systemd 229 and up, so using the old location
# to make them work for either version of systemd.
StartLimitBurst=3

# Note that StartLimitInterval was renamed to StartLimitIntervalSec in systemd 230.
# Both the old, and new name are accepted by systemd 230 and up, so using the old name to make
# this option work for either version of systemd.
StartLimitInterval=60s

# Having non-zero Limit*s causes performance problems due to accounting overhead
# in the kernel. We recommend using cgroups to do container-local accounting.
LimitNOFILE=infinity
LimitNPROC=infinity
LimitCORE=infinity

# Comment TasksMax if your systemd version does not supports it.
# Only systemd 226 and above support this option.
TasksMax=infinity

# set delegate yes so that systemd does not reset the cgroups of docker containers
Delegate=yes

# kill only the docker process, not all processes in the cgroup
KillMode=process

[Install]
WantedBy=multi-user.target

直接在ExecStart的啟動命令中新增-g /xxx 修改Docker Root Dir 。

# ExecStart=/usr/bin/dockerd -H fd://
ExecStart=/usr/bin/dockerd -g /data/docker/ -H fd://

重啟。

pi@raspberrypi:~/docker-config$ dosu service docker restart
Warning: docker.service changed on disk. Run 'systemctl daemon-reload' to reload units.
pi@raspberrypi:~/docker-config$ dosu systemctl daemon-reload
pi@raspberrypi:~$ docker images; docker ps -a
REPOSITORYTAGIMAGE IDCREATEDSIZE
CONTAINER IDIMAGECOMMANDCREATEDSTATUS

什麼東西沒有了。 繼續檢視：

pi@raspberrypi:~$ docker info | grep -i root
Docker Root Dir: /data/docker
pi@raspberrypi:~$

所以操作生效了。

注意：記得將原路徑的檔案(使用root)拷貝到新的目錄。這樣docker才能找到原先的映象和容器以及相關快取(Layer)等。

其實也可以在/etc/docker/daemon.json 中修改做修改。

By

本文連結